American College of Veterinary Radiology

Scientific Program2001 Annual Conference

August 5-10, 2001Waikiki Beach Marriott Resort, Honolulu, HI

Sunday August 5, 2001

7:00 a.m. - 5:00 p.m. Registration

Resident Seminar Thoracic Imaging

8:30 a.m. - 9:15 a.m. Basic Film Reading TechniquesDr. Allen

9:15 a.m. -10:00 a.m. Canine Lung DiseaseDr. Adams

10:00 a.m. -10:15 a.m. Break

10:15 a.m. - 11:00 a.m. Feline Lung DiseaseDr. O'Brien

11:00 a.m. - 11:45 a.m. Upper Airway and NasalDr. Stefanacci

11:45 a.m. - 1:00 p.m. Lunch

1:00 p.m. - 1:45 p.m. HeartDr. Poteet

1:45 p.m. - 2:30 p.m. Mediastinum and PleuraDr. Robertson

2:30 p.m. - 2:45 p.m. Break

2:45 p.m. - 3:30 p.m. Large AnimalDr. Neuwirth

3:30 p.m. - 4:15 p.m. Overview from Examination CommitteeDr. Henry

Monday August 6, 2001

7:00 a.m. - 9:00 a.m. Registration

All Day Poster Session

8:00 a.m. - 9:00 a.m. Welcome - ACVR President's Address

9:00 a.m. - 10:00 a.m.

Keynote PresentationMichael J. Meagher, MD, FACRThe Search for Contrast: Clinical Imaging atthe Cellular Level

10:00 a.m. - 10:15 a.m. Veterinary Radiology & UltrasoundResident's Paper Award

10:15 a.m. - 10:30 a.m. Break

10:30 a.m. - 12:30 p.m. Scientific Session #1General

12:30p.m. - 1:30 p.m. Lunch (Afternoon Free)

6:30 p.m. ACVR Welcome Reception

Tuesday August 7, 2001

7:00 a.m. - 8:00 a.m. RegistrationNuclear Medicine Society Meeting

All Day Poster Session

8:30 a.m. - 9:45 am Scientific Session #2Nuclear Medicine

9:45 a.m. - 10:15 a.m. Break

10:15 a.m. - 11:15 a.m.Break (Note: CT/MR Society Business Meetingpreviously scheduled in this slot was moved toThursday at 11:30 AM-12:30 PM)

11:15 a.m. - 12:00 p.m. Scientific Session #3CT/MRI & General

12:00 p.m. - 1:00 p.m. Lunch (Afternoon Free)

Wednesday August 8, 2001

8:00 a.m. - 9:00 a.m.RegistrationRadiation Oncology BusinessMeeting

All Day Poster Session

9:00 a.m. - 9:45 a.m.

Keynote PresentationSharon M. Hummel, RTT, CMDFuture Directions in Veterinary RadiationOncology Treatment Planning

9:45 a.m. - 10:15 a.m. Break

10:15 a.m. - 11:15 a.m. Scientific Session #4Radiation Oncology

11:15 a.m. - 11:30 a.m. Break

11:30 a.m. - 12:15 p.m. Scientific Session #5Ultrasound

12:15 p.m. - 1:00 p.m. Lunch

1:00 p.m. - 3:00 p.m. ACVR Business Meeting

3:00 p.m. - 3:30 p.m. Break

3:30 p.m. - 5:00 p.m. ACVR Film Reading Session

Thursday August 9, 2001

7:00 a.m. - 8:00 a.m. RegistrationUltrasound Society Meeting

All Day Poster Session

8:30 a.m. - 10:00 a.m. Scientific Session #6Ultrasound

10:00 a.m. - 10:30 a.m. Break

10:30 a.m. - 11:30 a.m. Scientific Session #7CT/MR

11:30 a.m. - 12:30 p.m. CT/MR Society Business Meeting

12:30 p.m. - 1:30 p.m. Lunch (Afternoon Free)

Friday August 10, 2001

Polynesian Cultural Center All Day Event

Monday August 6, 2001

Scientific Session #1General Radiology

Moderator: TBA

Time Presenter Title10:30 Allan Videofluoroscopic observations of collapsing airways

in dogs

10:45 Allan Evaluating canine dynamic airway disease

11:00 Becht Comparison of five imaging modalities to detect earlyosteoarthritis in the equine carpus

11:15 Fabiani Comparison of degree of angulation of obliqueimages for localization of extradural compressivelesions secondary to intervertebral disc herniation inthe thoracolumbar spine

11:30 Reed The incidence of coexisting hip and elbow dysplasiain dogs with cranial cruciate ligament rupture

11:45 Reichle Ureteral neoplasia in dogs

12:00 Thompson Observer performance in the diagnosis of canineheartworm disease using computed radiographyversus a conventional film-screen system

12:15 Badertscher "Screen discoloration"- as film artifact

Tuesday August 7, 2001

Scientific Session #2Nuclear Medicine

Moderator: TBA

Time Presenter Title8:30 Adams Combined surgery, radioiodine, and hormone

suppressive therapy in treatment of canine thyroidcarcinoma

8:45 Crevier Scintigraphic biodistribution of radiolabelled vitamin B-12 in normal dogs

9:00 Grimm The effect of a combination of medetomidine-butorphanol and medetomidine, butorphanol, andatropine on glomerular filtration rate in dogs

9:15 Poteet Perchlorate discharge test and 123-iodine uptake incongenitally hypothyroid puppy

9:30 Poteet Pulmonary thromboembolism associated with caninetotal hip replacement

Scientific Session #3CT/MR & General

Moderator: TBA

Time Presenter Title11:15 Frank Helical computed tomographic portal angiography in

dogs

11:30 Samii Diagnostic utility of computed tomography for theidentification of ureteral ectopia in dogs

11:45 Widmer Magnetic resonance contrast-a review and update

Wednesday August 8 , 2001

Scientific Session #4Radiation Oncology

Moderator: TBA

Time Presenter Title10:15 Lester Frameless stereotactic radiosurgery for treatment of

tumors of the head in small animals

10:30 Forrest Vinblastine, prednisone and coarse fractionatedradiotherapy for biologically high-grade cutaneousmast cell tumors in dogs

10:45 McEntee Radiation induced second tumor in dogs irradiated fororal acanthomatous epulis

11:00 King Prolonged remission and survival times in cats withinjection-site associated sarcomas using preoperativeradiation and doxorubicin protocol: 61 cases (1988-2000)

Scientific Session #5Ultrasound

Moderator: TBA

Time Presenter Title11:30 Wisner Evaluating contrast enhanced ultrasound as a method

for clinical monitoring of tumor angiogenesis in a ratmodel

11:45 Waller Perfusion measurements in the normal canine kidneyfollowing bolus injection of contrast agent

12:00 Ziegler Quantitiative evaluation of contrast enhancement ofcanine liver using harmonic ultrasound imaging

Thursday August 9, 2001Scientific Session #6

Ultrasound

Moderator: TBA

Time Presenter Title8:30 O'Brien Range ambiguity artifact in clinical sonography

8:45 Tidwell Sonographic findings in dogs and cats with intestinalperforation: a retrospective study (1995-2001)

9:00 Henry Unexpected findings in complete versus partialabdominal ultrasound examinations

9:15 Ramiriz Comparison of thoracic ultrasonography andradiography in 17 foals with Rhodococcus equipneumonia

9:30 Ramiriz Ultrasonographic features of canine abdomialmalignant histiocytosis

9:45 Ottesen Hereditary multifocal renal cystadenocarcinomas andnodular dermatofibrosis: assessment of US sensitivityfor early diagnosis

Scientific Session #7CT/MR

Moderator: TBA

Time Presenter Title10:30 Adams Pubic symphysiodesis in 22 puppies: CT and

radiographic results at two years of age

10:45 McKnight The feasibility of standing equine MRI: work inprogress

11:00 Rozear Evaluation of the ureter and ureterovesicular junctionusing spiral computed tomographic excretoryurography in normal dogs

11:15 Tidwell Clinical usefulness of fluid attenuated inversionrecovery-weighting, T2*-weighting, and chemical fatsaturation MRI techniques

Poster Session

Author Title

Wood Prolonged general anesthesia for magnetic resonanceobservations of the rat brain

Wood Sonographic observations of the canine elbow

Chang Evaluation of the experimental hydronephrosis treated withtransarterial embolization in beagle dogs

Chang The preliminary report: superparamagnetic iron oxide enhancedmagnetic resonance imaging of the liver in beagle dogs

VIDEOFLUOROSCOPIC OBSERVATIONS OF COLLAPSING AIRWAYS IN DOGS.

GS Allan * and AKW Wood. # University Veterinary Centre [Sydney], * University of Sydney,Sydney, NSW 2006, Australia; Department of Clinical Studies, # School of Veterinary Medicine,University of Pennsylvania, 3850 Spruce Street, Philadelphia, PA 19104-601, USA.

Introduction: Image intensified video-flouroscopy is routinely used to evaluate the airways of dogsand cats suspected of having respiratory problems caused by dynamic airway disease [DAD]. Thepurpose of this study was to describe the location, duration and extent of airway collapse in affecteddogs.Materials and Methods: Forty seven dogs were referred for radiologic studies of the airways. Afterclinical evaluation, survey radiographs of the trachea and thorax were made. Assessment of surveyradiographs for signs of airway collapse included calculation of the tracheal diameter:thoracic inletdiameter [TD:TID] ratios. Video-fluoroscopic observations of normal ventilation and during coughingwere recorded on videotape [44 dogs] or film using a 105mm camera [3 frames.s-1, 3 dogs]. Thelocation, duration and extent of airway collapse was recorded. The airways were divided into 5regions [cervical, thoracic inlet, thoracic, hilar and main bronchi] so that the location and extent ofcollapsing events could be defined. The duration of collapse was analysed from field-by-field replayof video recordings, with each field representing a 20ms event. At least 5 episodes of airway collapsewere analysed and the mean duration of collapse determined.Results: Six dogs were excluded from the study as they had no evidence of DAD. The remaining 41dogs with DAD comprised 25 males and 16 females. Their ages ranged from 2 - 22 years [Mean10.3+SD3.4] and their body weight from 1.6 - 27.4 kg [mean 6.3+SD5.2]. Small purebred dogs werefrequently affected, with poodles being the most common. Five dogs were of mixed breeding. Surveyradiographic signs suggestive of DAD were present in 11 dogs while video-fluoroscopy identifiedDAD in all 41 dogs. The TD:TID ratio was measured in 29 dogs. The ratio was normal in 18, reducedin 7 and increased in 4 dogs. Video-fluoroscopy identified cyclical variations in airway diameterduring normal ventilation in 20 dogs but in the other 21 dogs it was only observed during coughing.In order of frequency, airway collapse was observed extending from the thoracic inlet to the hilarregion in 17 dogs, in the distal trachea and main lobar bronchi in 11 dogs, the main lobar bronchi in 3dogs and in the cervical trachea in 2 dogs. In the remaining 8 dogs DAD was present in multiplelocations. The cause of airway collapse was dynamic compression of the tracheal lumen [31 dogs],combination of dynamic compression and a flaccid dorsal ligament [6 dogs] and obstruction of thelumen by a flaccid dorsal ligament [4 dogs]. In all 41 dogs at least 5 episodes of airway collapse wererecorded on videotape. The mean duration of collapse was 0.55+SD0.32s. The duration was longer inanimals with DAD during normal ventilation [0.68+SD0.39s] than when it was observed duringcoughing [0.42+SD0.15s]. Dynamic airway disease was the only clinical problem in 16 dogs. In allother dogs there was concurrent cardio-respiratory disease. Mitral valvular insufficiency [some withconcurrent tricuspid insufficiency] was present in 16 dogs. Seven had concurrent or recentdirofilariasis and 1 each had a supraventricular arrhythmia or laryngeal stenosis.Conclusion: Dynamic airway disease is a common cause of chronic coughing in dogs. Affectedanimals tend to be small, old and of purebreeding. Clinical signs of DAD can be distinctive butconfirmation of DAD is difficult. In this study we used video-fluoroscopy as the imaging modality ofchoice and successfully characterized the location, duration and extent of airway collapse in 41 dogs.The majority of affected dogs had more than one problem, so establishing the presence of DADshould be regarded as only part of a patient's workup. Management of DAD requires management ofall of the concurrent cardio-respiratory disorders that are seen in dogs with DAD.

EVALUATING CANINE DYNAMIC AIRWAY DISEASE

Skerman C, Allan G S, Nicoll R G and Church D B.University Veterinary Centre [Sydney], University of Sydney, Sydney, NSW 2006, Australia

Introduction: The purpose of this study was to compare the usefulness of several diagnosticmodalities to identify the presence of tracheal and/or bronchial collapse in dogs. In this prospectivestudy, veterinarians in the Sydney Metropolitan area were asked to refer any chronic coughing dog tothe University Veterinary Center [Sydney] for comprehensive evaluation.Methods: Thirty-eight dogs with a chronic cough of unspecified origin were assessed using surveyradiography, image-intensified video-fluoroscopy [IIVF], tracheobronchoscopy [TB] and modifiedbronchoalveolar lavage [BAL]. Survey radiography comprised five radiographs, being right lateralviews of the thorax during inspiration and expiration and inspiratory views using left lateral anddorsoventral projections of the thorax and a right lateral projection of the cervical trachea. Dynamicventilation studies using image-intensified videofluoroscopy were made on conscious dogs positionedin right lateral recumbency during normal ventilation and during coughing episodes. All dogs wereexamined tracheo-bronchoscopically under a light plane of general anaesthesia following collection ofairway secretions for cytological evaluation. An echocardiographic examination was done on any dogwith an audible cardiac murmur and/or radiographic evidence of left cardiomegaly. The radiographicand IIVF studies were supervised and evaluated by two ACVR Boarded veterinary radiologists.Results: Eighteen dogs were classed as having stable airway disease [SAD] and twenty dogs werecategorized as having dynamic airway disease [DAD], based on there being a proportional change inairway diameter of greater that 20% observed during tracheobronchoscopy. There was a strongcorrelation between observations using both IIVF and TB in 18/20 DAD dogs. There were two dogswhere DAD was diagnosed on the findings of only one study [One each IIVF and TB]. In ten dogs inthe DAD group with radiographic and echocardiographic evidence of left atrial enlargementsecondary to mitral valve endocardiosis, there was dorsoventral flattening of the left caudal lobarbronchus. Sterile inflammatory cytological changes were found in BAL samples of 36/38 dogs. In9/20 DAD dogs and 2/18 dogs with SAD there was a significant eosinophilia, but in other respects thecytological changes in the two groups of dogs was similar.Discussion: Plain radiography was not a reliable imaging study for the diagnosis of DAD.Observations obtained using IIVF and TB correlated well in this study. Tracheobronchoscopyidentified dynamic airway changes during light anaesthesia, when the cough reflex was intact. Duringdeeper anaesthesia, when the cough reflex was absent, DAD was unlikely to be observed. Because ofpractical problems associated with endoscopy in lightly anaesthetized dogs, TB was viewed lessfavourably that IIVF as the procedure of choice for evaluation of DAD. There were no distinctivecytological findings that correlated with the presence of DAD in the dogs in this study. The presenceof signs of flattening of the left caudal lobar bronchus in 10/10 DAD dogs with left atrial enlargementwas an interesting finding. There was only one dog in the SAD group with left atrial enlargement, andit did not have signs of bronchial flattening. Whether or not bronchial collapse and coughing wasexacerbated by left atrial enlargement was not determined. As a result of this study, we regard IIVF asthe procedure of first choice when evaluating coughing dogs suspected of having DAD.

COMPARISON OF FIVE IMAGING MODALITIES TO DETECT EARLYOSTEOARTHRITIS IN THE EQUINE CARPUS

J.L. Becht, DVM, MS., R.D. Park, DVM, PhD., C.E. Kawcak, DVM, PhD., D.D. Frisbee,DVM, PhD., P.F. Steyn, BVSc, MS., C.W. McIlwraith, BVSc, PhD., A.J. Kane, DVM,PhD. College of Veterinary Medicine and Biomedical Sciences, Colorado StateUniversity, Fort Collins, CO, 80523

INTRODUCTION AND JUSTIFICATION Osteochondral disorders in the equine athlete include cartilage erosion, fragmentation,subchondral bone lysis, sclerosis, micro-fracture and secondary periarticular osteophytedevelopment leading to fracture occurrence and/or degenerative joint disease.A common site for osteochondral disease is the distal medial aspect of the radial carpalbone. Many carpal fractures and larger subchondral defects are detected withconventional radiography, but smaller fracture fragments and more subtle subchondraland cartilage changes present a significant diagnostic challenge. Presently, veterinariansare searching for improved diagnostic modalities to identify horses with small, subtlelesions in bones and cartilage that may predispose to fracture. Methods for determiningthe extent of the disease process are also needed. Identification of horses with abnormalbone remodeling and/or cartilage damage would enable adjustment of exercise orperformance schedules to prevent fracture occurrence, which often results in careerending and life threatening conditions. The objective of this experimental study was todetermine the sensitivity and specificity of five diagnostic imaging modalities(conventional radiography, bone scintigraphy, CT, MRI and CT osteoabsorptiometry) inthe detection of subchondral bone changes and articular cartilage injury in the radial andthird carpal bones of 2-4 year-old exercised horses.

MATERIALS AND METHODS Eight horses of mixed breeding, 2-4 years of age, were randomly divided into twogroups (surgically created carpal lesion and non-surgical controls). In those havingsurgery, a subchondral fragment on the distal articular surface of the radial carpal bonewas created. Following a recuperation period, all horses were exercised for 12 weeks.Imaging of all carpi included conventional radiography and bone scintigraphy at thebeginning and conclusion of the study, and CT, MRI and CT osteo-absorptiometry at theconclusion of the study. Also at the conclusion of the study, gross and histopathologicchanges were characterized and served as the gold standard to which the various imagingmodalities were compared.

RESULTS AND DISCUSSION Conventional radiography identified created bone fragments, but added little to furthercharacterize pathologic changes. Bone scintigraphy was a sensitive indicator of boneremodeling. CT and MRI greatly improved the ability to quantitate subchondral bonechanges associated with exercise-induced bone remodeling, and those associated with thecreated subchondral defects. CT osteo-absorptiometry yielded useful quantitative data ofbone density changes. Sensitivity and specificity for detecting articular cartilage andsubchondral bone changes will be presented for each modality.

COMPARISON OF DEGREE OF ANGULATION OF OBLIQUE IMAGES FORLOCALIZATION OF EXTRADURAL COMPRESSIVE LESIONS SECONDARY TOINTERVERTEBRAL DISC HERNIATION IN THE THORACOLUMBAR SPINE

Michelle H. Fabiani, D.V.M., Brian A. Poteet, D.V.M., Andra Voges, D.V.M., Jolie Jarboe,D.V.M., Gulf Coast Veterinary Specialists. Houston, TX 77027

IntroductionMyelography is a commonly used imaging modality for the diagnosis of extradural spinal cordcompression due to intervertebral disc herniation. Guided by myelographic results,decompression at the site and side of the diagnosed abnormality is routine. Recent articles havestated the need for oblique views to identify ventral and slightly ventrolateral intervertebral discherniation. The purpose of this study is to evaluate the optimum degree of angulation of obliqueimages necessary to improve accuracy of diagnosis of extradural spinal cord compressivelesions.

MethodsSurvey ventrodorsal and lateral films, ventrodorsal and lateral views following lumbar puncturemyelography, and “small angle”, "intermediate angle" and “large angle” oblique films alsofollowing lumbar puncture myelography from 20 dogs were obtained. “Small angle” is definedas slightly obliqued off ventrodorsal (10 to 20 degrees). "Intermediate angle" is defined asmoderately obliqued off ventrodorsal (approximately 45 degrees). “Large angle” is defined asseverely obliqued off ventrodorsal (70 to 80 degrees). All films were reviewed by two boardcertified radiologists, one board eligible neurologist, and a third year radiology resident inblinded fashion. Both longitudinal site and circumferential side were identified from theavailable images. Other parameters related to ability to accurately diagnose the site and side oflesion, such as history of previous spinal surgery, radiographic degree of compression, breed,age, and weight of dog were evaluated for statistical significance. Radiographic conclusionswere compared to surgical findings.

ResultsTo be presented.

The Incidence of Coexisting Hip and Elbow Dysplasia in Dogs with CranialCruciate Ligament Rupture.Ann L. Reed, DVM, MS, Dipl. ACVR, Kathryn D. Olson, RT, RDMS, FrankBorostyankoi, DVM, Robert L. Rooks, DVM, MS, Dipl. ACVS, ABVP.All-Care Animal Referral Center, 18440 Almistad St., Fountain Valley California 92708Introduction: Cranial cruciate ligament rupture (CrCLR) is one of the most commoncauses of hindlimb lameness in dogs. Rupture most often appears to be secondary todifferent types of chronic stresses leading to progressive irreversible deterioration. Theorigin of these stresses may be associated with abnormal limb conformation and/orobesity. Abnormal weight distribution caused from coexisting abnormalities in otherlimbs may also be an important factor leading to its deterioration. The objective of thisretrospective study was to determine the incidence of coexisting hip dysplasia (HD) andelbow dysplasia (ED) in dogs with CrCLR and compare the incidence to a controlpopulation of dogs. In addition, differences in the frequency of CrCLR between breeds,sex, age, weight and unilateral versus bilateral disease were analyzed.Materials and Methods: All dogs presented to the All-Care Animal Referral Center forhindlimb lameness associated with CrCLR had lateral and cranio-caudal radiographsperformed of both stifles. In addition, standard ventrodorsal and lateral radiographs ofthe pelvis and flexed lateral and cranio-caudal views of the elbows were performed.Radiographs of a total of 258 dogs were evaluated for radiographic evidence of HD, EDand CrCLR in the stifles. All 258 dogs had arthroscopic surgery performed to confirmCrCLR. In addition, radiographs of 101 control dogs presented for routine hip and elbowscreening for Orthopedic Foundation for Animals were evaluated for the incidence of HDand ED. Stifles were evaluated on ventrodorsal views of the pelvis and if no evidence ofdegenerative joint disease was seen, they were presumed to be normal. Radiographswere evaluated by a single board-certified veterinary radiologist and Chi-square analysiswas performed to determine the statistical significance of results.Results: Of the 258 dogs with CrCLR, 197 (76%) had coexisting HD and/or ED. Ofthese 197 dogs, 67 (26%) had both HD and ED, 48 (18%) had HD and 82 (32%) had ED.A total of 152 dogs (58%) had bilateral CrCLR and 106 dogs (41%) had unilateralCrCLR. There were 32 dogs with unilateral CrCLR that also had coexisting unilateralHD and/or ED. Twenty-three of these dogs (71%) had contralateral HD and/or ipsilateralED observed to the side of the unilateral stifle with CrCLR. There were 173 females(68%) and 85 males (32%) with CrCLR and 235 of these dogs (91%) were over 30 lbsand 148 (57%) were over the age of 5 years. The largest breed percentages observedwere Rottweilers (17%) and Golden Retrievers (12%). Of the 101 control dogs, only 24(21%) had coexisting HD and ED. The percentage of frequency of coexisting HD andED dysplasia in the 258 dogs studied compared to the frequency found in the controlgroup was highly significant (p<.01).Conclusion: The results of this study suggest that coexisting HD and/or ED are commonin dogs with CrCLR and may play an important role in its pathogenesis due to chronic,abnormal weight distribution causing increased cranial cruciate ligament stress.

URETERAL NEOPLASIA IN DOGS.

JK Reichle, DVM, MS, DACVR;1 RA Peterson, DVM;2 PY Barthez, DVM, PhD, DACVR;1

Ohio State University (OSU) College of Veterinary Medicine, Veterinary Clinical Sciences1 andVeterinary Biosciences;2 Columbus, OH 43210.

Introduction/Purpose: The purpose of this study was to describe the diagnostic imagingfindings of ureteral neoplasia in dogs.

Methods: Two canine patients of OSU with proximal ureteral transitional cell papilloma wereincluded in this study, in addition to 4 cases of ureteral neoplasia in the literature.

Results: Ages of the dogs ranged from 7-12 years. Three were intact males, 1 was a castratedmale, and 2 were intact females. Clinical signs included urinary incontinence, urinary tractinfection, hematuria, fever, and/or anorexia. Physical examination in some dogs revealeddetection of an enlarged or painful kidney secondary to hydronephrosis. All cases of ureteralneoplasia had obstructive hydronephrosis and hydroureter. Diagnostic methods includedultrasonography, which revealed a homogenous intraluminal ureteral mass in 2 cases ofpapilloma; the affected renal pelvis and section of ureter proximal to the mass were distended. Inone case, ultrasound-guided antegrade pyelography was performed and demonstrated severehydronephrosis and hydroureter proximal to an oval intraluminal filling defect. Renalscintigraphy with 99mTc-diethylene-triaminepentaacetic acid (99mTc-DTPA) demonstrated overallnormal global glomerular filtration rate, but poor function and a plateau of the time-activitycurve of the affected kidney and ureters was noted. All 3 transitional cell papillomas were inmale dogs. Two of the papillomas (from OSU) were located in the proximal ureter; anotherpapilloma from a case in the literature was in the mid-ureter. Cases of leiomyoma,leiomyosarcoma, and transitional cell carcinoma were all found in the distal ureter.

Discussion/Conclusion: Various methods are valuable in the diagnosis of ureteral neoplasia.Ureteronephrectomy can be curative, since metastasis and recurrence has not been reported inany of these cases. Interestingly, papillomas of the ureter have been reportedly more common inmale humans and have a high incidence of being located in the proximal left ureter. In general,for humans and canine patients, benign ureteral neoplasia is more likely to be located in theproximal ureters while malignant neoplasia is more likely to be located distally within theureters.

OBSERVER PERFORMANCE IN THE DIAGNOSIS OF CANINE HEARTWORMDISEASE USING COMPUTED RADIOGRAPHY VERSUS A CONVENTIONALFILM-SCREEN SYSTEM

M.S. Thompson, DVM; J.P. Graham MVB, MSc; G.D. Roberts, DVM, MS;T. Miyabayashi, BVS, MS, PhD; N.V. Lester, BVMS; F.G. Martin, PhD., S.M. Newell, DVM, MSDept. of Small Animal Clinical Sciences, University of Florida, PO Box 100126, Gainesville, FL 32610

Introduction: Computed radiography (CR) uses an image plate to record the x-ray image as apattern of electron charges. The plate is scanned with a laser resulting in luminescenceproportional to the stored x-ray energy. The emitted light is collected by a photomultiplier tubeand converted to a digital signal and processed to generate an image. CR offers advantages inimage manipulation including edge enhancement, adjustable gray scale, and increased exposurelatitude. In order to replace film screen radiography (FSR) with CR systems in veterinarymedicine, it is necessary to demonstrate that CR is at least as accurate in detecting abnormalities.

Methods: Canine heartworm (HW) disease was chosen as a model to compare the CR systemwith a conventional FSR system. Thirty-five clinically normal to moderately symptomatic dogs,serologically positive for Dirofilaria immitis and twenty-five serologically negative control dogswere evaluated radiographically for evidence of infection. Right lateral and ventro-dorsalprojections of the thorax were obtained using both systems, with CR images acquiredimmediately after each FSR film. The CR images were processed and printed in a dual imageformat. One algorithm was designed to enhance vessels and the second to produce moderateedge enhancement.

Four radiologists, blinded to the patient’s serologic status, evaluated twelve sets (10-12cases) of randomized CR and FSR images. Radiographs were assessed for diagnostic qualityand the following criteria – cardiac enlargement, main pulmonary artery enlargement,enlargement of specific pulmonary artery segments and lung abnormalities. The evaluators wereasked to make a diagnosis of the patient’s heartworm status and indicate a level of confidence.

Results: When all observers were combined, the overall sensitivity and specificity ofheartworm disease detection was similar for both systems. Detection of heartworm associatedlesions was fair for both radiographic systems. Moderate inter- and intra-observer variabilitywas noted. Two observers had slightly better detection of true HW positives on FSR, thoughthis finding was not statistically significant; while two had very good specificity on the CR films.

Conclusions: Based on these data, thoracic radiography is an insensitive test for canineheartworm infection. Thoracic films obtained with this CR system had similar sensitivity andspecificity to the FSR system. This indicates that CR could replace conventional systems incanine thoracic radiography, specifically in the evaluation of heartworm disease. The moderateinter- and intra-observer variability indicates that relative observer experience with CR may be afactor.

"Screen Discoloration"—As Film Artifact.

Robert R. Badertscher II, D.V.M., Ph.D., & Richard Carlson D.V.M

Numerous artifacts are routinely seen on radiographs presented from referringveterinarians, most of which have been previously described and are part of thecertifying examination for the ACVR. Recently however, a series of radiographsfrom over 6 veterinary facilities, have presented with artifacts that have notpreviously been reported. The primary findings are consistently under-exposedfilms from the same practice, using the same size cassette, and showed nosignificant change in radiographic density even with significant increases inexposure factors. Evidence of quantum model, with small black specks andstreaks were also seen in the under-exposed regions of the film.

Examination of the cassettes from these practices showed the screens oftenhave a yellow tinge, that could not be removed with commercial screen cleaningsolutions. In two separate practices, new Quanta III (blue sensitive), rare-earthscreens, manufactured by Du Pont (Sterling), had been purchased within the lastsix months. Further study of the problem, showed there was a film screenmismatch, with a private-label (“white-box”) film that had been manufactured by adifferent company. The screens were subsequently replaced, and theappropriate film - screen combinations were used as recommended by themanufacture, with elimination of the artifacts”.

This “Screen Discoloration” artifact can be caused by the migration of chemicalcomponents in the emulsion layer of the film, through the film’s abrasive layer,penetrating the top coat of the screens and interacting with the phosphor of thescreens. The discoloration can also be do to migration of dye from some filmsthrough the top coat of the screen into the screen phosphor. In some cases acolorless component in the binder of the film might also cause a chemicalreaction with the screen phosphor, without any visible screen discoloration.Another factor that has been suggested to exacerbate these chemical reactionsis the long term storage of film within the cassettes, which is enhanced in humidconditions or with high temperatures.

Since many veterinary practices attempt to reduce costs by purchasing private-label film, this artifact has been seen more commonly. It is important that theveterinary radiologists recognize this unusual pattern, in order to advise theirclients of the need for following the manufacturer’s guidelines of using compatiblefilm and screens. The long-term costs of periodically replacing screens in eachcassette and the degradation of image quality does not appear to justify the shortterm savings of purchasing incompatible privately label film.

COMBINED SURGERY, RADIOIODINE, AND HORMONE SUPPRESSIVE THERAPYIN TREATMENT OF CANINE THYROID CARCINOMA - 16 CASES

WH Adams DVM, GB Daniel DVM MS, AM Legendre DVM MS, IF Lane DVM MS.University of Tennessee College of Veterinary Medicine, Knoxville, TN 37901

Introduction: Canine thyroid carcinoma is a common tumor representing 1 - 4% of all canineneoplasms and 15% of tumors of the canine head and neck. It is a locally invasive, malignanttumor with tendency for both locoregional and pulmonary metastasis. Consequently, adjunctivesystemic therapy is indicated following surgical resection to treat both residual disease in thesurgical bed and distant disease. Radioiodine has proven efficacy in treating thyroid cancer inpeople. This study reports our experience in treatment of canine thyroid carcinoma utilizingsurgery and radioiodine.

Methods: Sixteen dogs with biopsy confirmed thyroid carcinoma are included in thisretrospective study. All dogs underwent surgery for removal of a primary thyroid carcinomaeither at the referring hospital or the Veterinary Teaching Hospital of the University ofTennessee (UTVTH). All dogs had pretreatment thyroid scintigraphy for staging and todetermine functional status of primary and/or secondary tumor foci. Pretreatment database alsoincluded complete blood count (CBC), 3-view thoracic radiographs and serum T4 " TSHdetermination. Following recovery from surgery, all dogs received radioiodine (131I) at anempirical dose. Following release from isolation, most dogs had immediate post-treatment CBCand T4 " TSH measurements. Most dogs returned for post-treatment scintigraphy and thoracicradiographs. Following initial post-treatment scintigraphy, most dogs were given daily thyroxinesupplementation.

Results: Two dogs were hyperthyroid prior to surgery. No dogs were hyperthyroid at the time oftreatment and 7 dogs were hypothyroid based on T4/TSH values. Surgical procedure involvedremoval of a single thyroid lobe (11 dogs), removal of both lobes (3 dogs), removal of an ectopicmass (1 dog) and removal of an ectopic mass and single thyroid lobe (1 dog). Residual tumor inthe surgical bed and distant metastasis were suspected or documented in 12 dogs based onhistopath report (extension of tumor beyond margins, positive lymph node, vascular andlymphatic invasion) or scintigraphic evidence of pulmonary or mediastinal radionuclidelocalization. Empirical doses of 131I ranged from 41 to 137 mCi. The major complicationobserved was myelosuppression seen in 11 of 14 dogs evaluated. In 9/11 dogs, leukopenia andthrombocytopenia were mild and transient without clinical signs. Two dogs developed severefatal myelosuppression. To date, 3 of 16 dogs have died of tumor related causes including the 2dogs with fatal myelosuppression and one dog with progressive pulmonary metastasis. Six dogshave died of non-tumor related causes and seven dogs remain alive. Updated survival data willbe presented.

Conclusion: Adjunctive use of radioiodine is an effective treatment of canine thyroid carcinoma.A relatively high incidence of myelosuppression is seen posttreatment. While mild and transientin most patients, fatal complications have been documented.

SCINTIGRAPHIC BIODISTRIBUTION OF RADIOLABELLEDVITAMIN B-12 IN NORMAL DOGS

P.F. Steyn, B.V.Sc., M.S.*, D.A. Collins, M.D.#, F.R. Crevier, D.V.M.*, J.L. Uhrig,C.N.M.T.* *Dept. of Radiological Health Sciences, Colorado State University, FortCollins, CO 80523 and #Mayo Clinic, Rochester, MN 55905.

Introduction: Cellular uptake of Cobalamin or Vitamin B-12 (B12) is regulated by cellmembrane transcobalamin II receptors and is up-regulated in rapidly dividing neoplasticcells. A B12 analog, DTPA- adenosylcobalamin (DAC), has been successfully labeledwith Tc99m and In111. Biodistribution studies have been performed in pigs and inhumans with clinically diagnosed malignancies. In the pigs and humans, there is intenselocalization of In-111 DAC in the facial region (nasal cavity and salivary glands), liverand spleen as well as the urinary bladder, consistent with urinary excretion. Mild diffuseactivity was observed in the GI tract. Various lymphomas and sarcomas as well as lung,breast, CNS and thyroid tumors have been delineated with In-111 DAC in humans. Thepurpose of this study is to describe the biodistribution of a radiolabeled B12 analog(DAC) in normal dogs prior to evaluating canine malignancies.

Methods: 8 normal beagles with no history or clinical evidence of neoplasia receivedintravenous injections of In-111 labeled DAC at 0.8-1.1 mCi per dog. Five minute planarimages were acquired of the following regions: dorsal pelvis, dorsal spine, ventralsternum (including forelimbs), right and left lateral pelvis and hindlimbs, right and leftthorax and head (includes forelimbs). The images were obtained approximately 2 hoursafter injection of the radiopharmaceutical. Images were subjectively evaluated forradiopharmaceutical uptake in various organs. For objective evaluation of the differentialuptake of the radiopharmaceutical, a region-of-interest (ROI) was drawn around thetarget organ, or representative portion thereof, taking care not to include other organs intothe ROI. Organs/areas evaluated were: muzzle, parotid salivary gland, cranial vault,heart, dorsal lung, popliteal lymph node, tricipital muscle mass, distal brachium, liver,left and right kidneys, small intestine, urinary bladder and foot pads. The mean numberof counts per pixel (CPP) was calculated in each organ/area by averaging CPP valuesfrom three ROI’s per organ/area. Ratios between the organ/area to be evaluated and thepredetermined control region (distal brachium) will allow comparison and quantificationof radiopharmaceutical uptake by similar regions in different subjects.

Results: Subjectively, little to no uptake (background) was seen in the cranial vault,neck, lungs and limbs. Very mild uptake was seen in: muzzle, parotid salivary gland,popliteal lymph node, footpads and the heart. Moderate uptake was seen in the liver andintestine. The stomach and kidneys showed a high level of uptake while the urinarybladder showed the most uptake due to urinary excretion. Quantitative Scintigraphicanalysis of target to non-target radiopharmaceutical uptake ratios will be presented.

Discussion: In-111 DAC could be used to image clinically suspected canine tumorslocated in the head and neck region, thorax, lymph nodes, and extremities.

THE EFFECT OF A COMBINATION OF MEDETOMIDINE-BUTORPHANOL ANDMEDETOMIDINE, BUTORPHANOL, AND ATROPINE ON GLOMERULAR

FILTRATION RATE IN DOGS

J.B. Grimm, D.V.M., K.A. Grimm, D.V.M., M.S., S.K. Kneller, D.V.M., M.S.,W.J .Tranquilli, D.V.M., M.S., S.S. Crochik, D.V.M., M.S., M.G. Bischoff, D.V.M.,J.L. Podolski, D.V.M. College of Veterinary Medicine, University of Illinois, Urbana, IL, 61802.

Introduction/Purpose: To measure GFR by nuclear scintigraphy, the patient must remainnearly motionless. Chemical restraint can be employed to reduce or eliminate motion in order toobtain accurate results. It is important that the effects of any sedative protocol on GFRmeasurement be known to reduce potential procedural error or bias in GFR assessment.Medetomidine is a potent alpha-2-adrenergic receptor agonist that increases systemic vascularresistance. Mean arterial pressure increases transiently following medetomidine administration,most often resulting in a reflex slowing of heart rate. Co-administration of atropine reduces theincidence of bradycardia but can result in a rapid and prolonged increase in mean arterialpressure, often over 200 mm of Hg.

Methods: GFR was measured by 99mTc-DTPA nuclear scintigraphy in six healthy dogs fifteenminutes after intramuscularly administered saline; medetomidine (11 µg/kg) and butorphanol(0.22 mg/kg) (MB); or medetomidine (11 µg/kg), butorphanol (0.22 mg/kg), atropine (0.044mg/kg) (MBA). Each dog received all treatments in random order with a minimum of one weekbetween treatments. Direct systolic, diastolic, and mean arterial blood pressures and heart ratewere measured at regular time intervals before, during, and after GFR calculations. One wayanalysis of variance (ANOVA) for repeated measures and Tukey’s pairwise comparison ofmeans test was used for statistical analysis of the GFR measurements and cardiopulmonary data.A value of p < 0.05 was termed statistically significant.

Results: Mean total GFR values (+/- SD) following MBA (3.82 +/- 0.24 ml/min/kg) and MBadministration (4.44 +/- 0.25 ml/min/kg) were higher than following saline (3.41 +/- 0.21ml/min/kg). There was no significant difference in the mean total GFR following MBAtreatment versus saline treatment (p = 0.176). However, there were significant differences in theGFR values following MB compared to saline (p = 0.002) and MBA (p = 0.034). During GFRdetermination, diastolic and mean arterial blood pressure following MBA injection weresignificantly greater than following MB (p = 0.004) or saline administration (p = 0.002).Diastolic and mean arterial blood pressures following MB injection were not significantlydifferent from saline (p = 0.791). At the time of the GFR study, the mean heart rate in dogsgiven MB was significantly lower than that recorded for dogs receiving MBA (p = 0.004) orthose given saline (p = 0.043). Heart rate following MBA injection was higher than followingsaline, but it was not significantly different (p = 0.341).

Discussion/Conclusions: In conclusion, the administration of medetomidine in combinationwith butorphanol significantly increases total GFR in healthy dogs, while the administration ofthe combination of medetomidine, butorphanol, and atropine does not.

This research was funded by the American College of Veterinary Radiology.

PERCHLORATE DISCHARGE TEST AND 123-IODINE UPTAKE IN ACONGENITALLY HYPOTHYROID PUPPY

Brian A. Poteet, DVM, Michelle H. Fabiani DVM, Cynthia Sloan DVM, Gulf Coast VeterinarySpecialists, Houston, TX, Kit Kampschmidt, DVM, Brittmoore Animal Hospital, Houston, TXand John C. Fyfe, DVM, PhD, Michigan State University, East Lansing, MI.

IntroductionCongenital hypothyroidism (CH) in dogs is a rare condition. Primary CH can be divided

into 4 categories: thyroid dysgenisis, dyshormonogenisis, thyroid hormone transportabnormalities, and metabolic defects following ingestion of goitrogens. In humans, 90% of CHindividuals have thyroid dysgenisis, while the majority of the others have an inherited inability toorganify iodide to iodine. The perchlorate discharge test is used to confirm the presence of anorganification defect.Methods A 2 month old, 1 pound, Toy Fox Terrier puppy was referred for continued workup ofsuspected congenital hypothyroidism. The puppy was stunted in growth, had disproportionatebody features, an abnormally long hair coat and thickening of the skin. A normal puppy of sameage and breed was also presented and was used as a control. Analyses of serum T3, T4, fT3, fT4and TSH levels were performed in the affected and control puppies both while receiving andafter 6 days withdrawal from oral thyroid hormone replacement. 500 uCi of 123-I solution wasinjected IV followed by thyroid imaging at 4 and 24 hours. All images were obtained using alarge field of view gamma camera and pinhole collimation. Radioiodine uptake (RAIU) wascalculated at 4 hours and 24 hours for both puppies. Static images of the thyroid were alsoperformed at 4 hours post-injection. Immediately following the 24 hour images, 50 mgs ofpotassium perchlorate (Perchloracap) was administered orally to each puppy, and newradioiodine uptake calculations were performed at 1 and 2 hours post-administration.Radiographs of the entire skeleton were also obtained on both puppies.Results

While on oral thyroid hormone replacement, the serum hormone profile of the affectedpup was within normal limits. After 6 days withdrawal from oral thyroid hormone replacement,the affected pup's total T4 and T3 were 0.0 and 0.1 nmole/L (normals were 35 and 1.2,respectively), fT4 and fT3 were 1.0 and 1.5 pmole/L (normals were 24 and 5.5, respectively),and TSH was 103 mU/L (normal was 11). These data confirmed normal hypothalamic-pituitaryaxis function in the affected pup, and that the thyroid gland was incapable of producing thyroidhormone. The image quality of both puppies thyroid's was excellent using 123-I. The thyroid glandof the abnormal puppy was approximately twice the size of the control puppy. Calculated RAIUfor the normal puppy was 3% and 6.7% at 4 hours and 24 hours, respectively. RAIU for theabnormal puppy was 33% and 17% at 4 hours and 24 hours, respectively. RAIU at 1 hour post-perchlorate administration was 3.4% for the abnormal puppy and 6% for the normal puppy. Thethyroid scan appeared unchanged on the post-perchlorate images in the normal puppy, while inthe abnormal puppy, there was complete washout of the radionuclide from the thyroid gland. Theperchlorate discharge test is useful in confirming the presence of a primary organification defectin hypothyroid canines.

PULMONARY THROMBOEMBOLISM ASSOCIATED WITH CANINE TOTAL HIPREPLACEMENT

Brian A. Poteet, DVM, William D. Liska, DVM, Gulf Coast Veterinary Specialists, 1111 WestLoop South, Houston, Texas 77027

IntroductionCanine total hip replacement (THR) is a commonly performed procedure used to resolve

pain and dysfunction secondary to coxofemoral arthritis. The procedure establishes a pain freejoint with normal function. Complications can arise including luxation, infection, asepticloosening, femur fracture, sciatic neuropraxia, and patella luxation. Death associated with theprocedure is very rare. A potential non-anesthesia cause for death is pulmonarythromboembolism (PTE). This investigation was conducted to evaluate the incidence of PTEand to report the risk and significance.Methods

Complications that arose in a series of 400 consecutive THR procedures were reviewed.The 400 THR’s were performed on 312 (88 Bilateral THR's) clinical canine patients by the samesurgeon over 8 years (1992-1999) with a minimum of 11 months follow-up. Pulmonaryperfusion scans were performed 5 minutes after 99mTc-MAA injection on 30 consecutive dogs.Radiographs (left lateral, right lateral, and ventro-dorsal projections) were taken immediatelypostoperatively and at the time of the lung scans. Transesophageal and intercostalultrasonography looking at the right atrium, right ventricle, and pulmonary outflow tract wasperformed on 10 consecutive dogs intraoperatively during the time of femoral component steminsertion.Results

The lung perfusion scans on the 30 asymptomatic dogs demonstrated multiple, diffuse,small, non-segmental perfusion defects. No particular lung lobe was more affected than theothers. Similar appearing defects have been described in the human literature and suggestspossible fat embolization. None of the dogs had any abnormal pulmonary clinical signs and nopulmonary radiographic abnormalities were evident. Ultrasonography revealed visible evidenceof embolemia in 8 of the 10 dogs evaluated. The emboli were observed entering the heart within5-10 seconds after insertion of the femoral stem into the cement in the femoral canal. Theemboli had the appearance of air bubbles in 2/8 and tissue particles in 6/8. No emboli wereobserved in 2/10 dogs. Air bubbles entering the right atrium became “trapped” in the dorsalaspect of the chamber. The air in the atrium could be dislodged forming multiple small bubblesby aggressively shaking the thorax. The tissue particles entering the heart varied in appearancefrom a homogeneous “snow storm” to a “hail” of multiple various sized globules up to 2 cm inlength. Embolemia lasted a variable time but was typically over within 45 seconds. The sourceof all embolemia is unclear. It is more likely to originate in cancellous bone in the proximalfemur than from the endosteum of the mid-diaphyseal medullary canal. Pressurization of thecement during femoral stem implant insertion results in embolemia of a “snow storm” or “hail”of echogenic particles in the right heart. Fortunately, most dogs are apparently able to recoverspontaneously as evidenced by the extremely low mortality rate even though the morbidity ishigher. The complication should be taken seriously since one dog died of PTE, even thoughthere was only one death in a group of 400 cases. The exact incidence of mortality is unknown.

HELICAL COMPUTED TOMOGRAPHIC PORTAL ANGIOGRAPHY IN DOGS.P. Frank, D.V.M., M. Mahaffey, D.V.M., M.S., C. Egger, D.V.M., M.V.sc.University of Georgia, College of Veterinary Medicine. Athens, GA. 30602

Introduction: In people, contrast enhanced helical computed tomography (CT) of the liver andportal system is often performed. Indications in people include evaluation of portal vasculaturesecondary to portal hypertension, evaluation of transjugular intrahepatic portosystemic shuntpatency, detection of portosystemic shunts (PSS), evaluation of suspected liver disease,evaluation of liver neoplasia, and evaluation for surgical planning (neoplasia). These can usuallybe accomplished in people with a breath-hold technique to minimize motion. This results in arelatively short duration outpatient procedure, in contrast to the more invasive methods of portalvisualization (percutaneous transhepatic portography, cranial mesenteric angiography,percutaneous splenoportography, etc.). Helical CT has advantages over traditional sequential CTin that it is faster (important for breath-hold duration, duration of maximal vascularenhancement), gives lower patent radiation dose in some instances, and can be reconstructed inthree dimensions better than sequential data. Many papers discuss the optimal scan parameters,injection parameters, and delay times with little consensus. The purpose of this project was todevelop a practical protocol for helical CT portography in the dog. Although the indications forthe procedure are similar to those in humans, the overwhelming majority of the anticipated use isfor evaluation of dogs with known or suspected PSS.Methods: Ten clinically normal dogs with normal liver function were evaluated. Each patientwas anesthetized and placed in dorsal recumbency. An intravenous catheter (18-20 G) wasplaced in a cephalic vein and connected to a power injector. A test dose of sodium iothalamate(400 mg I/ml) at 0.55 ml/kg was made(5 ml/s) and serial images were acquired at the level ofT12-13 or T13-L1. From this data the time to maximum enhancement of the portal vein wasdetermined. This time was used as a delay time for the second, main injection of 2.2 ml/kg.After the previous scan delay time, a helical scan of the cranial abdomen was made in a caudal tocranial direction. Prior to the beginning of the helical scan, the patient was manuallyhyperventilated to minimize breathing motion during the scan. Both injections were made at animposed limit of 300 psi, and scan parameters (slice thickness, pitch, reconstruction interval,etc.) were customized to the size of the patient and the capabilities of the scanner. Additionally,three clinical patients with scintigraphically confirmed shunts have been evaluated to this date.Results: All scans have been successful. Scan delay times for normal dogs were 34.5 s to 66 s(median: 43.5 s). When compared to the weight of the patient the times were 1.41 s/kg to 4.12s/kg (median: 2.09 s/kg). For patients with a PSS, the scan delay times were 21-39 s (median: 30s) and 1.47 - 7.40 s/kg (median: 2.60 s). Scan parameters used for all patients varied from 3 to 5mm slice thickness, 1.4 to 1.8 pitch, and reconstruction interval of 1/2 the slice thickness. Theaorta, caudal vena cava, portal vein, and their respective branches were well visualized. Theshunt vessels in all clinical cases were well visualized. No significant damage to the catheterswas noted on visual examination immediately post scan. Systolic blood pressure and expiredCO2 remained within normal limits. All patients recovered without incident.Discussion: We believe that this technique of helical CT portography (HCTP) in the dog will bea useful adjunct in the diagnosis of PSS. The use of HCTP may allow clinicians to give clients amore accurate prognosis prior to surgery and may allow patients with lesions that are notsurgically correctable to avoid a costly, invasive, and fruitless procedure.

DIAGNOSTIC UTILITY OF COMPUTED TOMOGRAPHY FOR THEIDENTIFICATION OF URETERAL ECTOPIA IN DOGS. V.F. Samii. D.V.M.,

M.A. McLoughlin. D.V.M., M.S., J.S. Mattoon. D.V.M., Wm.T. Drost. D.V.M.,D.J. Chew. D.V.M. Department of Veterinary Clinical Sciences, The Ohio State

University, Columbus, OH 43210

Introduction: Contrast-enhanced computed tomographic (CT) evaluation of theurogenital tract of normal dogs has been reported. The purpose of this study was todetermine the diagnostic utility of CT for the diagnosis of ectopic ureters in the dog andto compare these findings with conventional techniques of excretory urography,urethrography and sonography.

Methods: Three female dogs, each with a history of urinary incontinence since birthdespite normal voiding patterns, were evaluated. One adult male dog with a recent historyof urinary incontinence was also evaluated. Described protocols for radiographic,sonographic and cystoscopic evaluation of the urinary tract were followed. Pre-contrastCT images of the urinary tract consisted of 10 mm, transverse helical slices from thecranial aspect of the right kidney through the urethra. In female dogs, the vaginal vaultand vestibule were also imaged. Following intravenous administration of iodinatedcontrast medium (Iohexol 240, 1 ml/lb) the pre-contrast sequence was repeated. Thissequence was initiated 3 minutes after contrast medium administration. A series of 3 mmtransverse contiguous images from the trigone region through the urethra were obtained5, 15, and 30 minutes post-contrast administration. In female dogs the vaginal vault andvestibule were also imaged. Excretory urography, urethrography and contrast-enhancedCT procedures were performed on separate days to avoid cross-contamination ofintravenously administered iodinated contrast medium. Sonographic and cystoscopicevaluations followed either radiography or CT. The presence or absence of ureteralectopia was determined on cystoscopic evaluation. Image interpretation was compared tocystoscopy results by three board-certified radiologists (VFS, JSM, WTD). Descriptivestatistics and ANOVA test results are pending.

Results: All four dogs were determined to have bilateral ureteral ectopia on CT andurethrography. This finding was confirmed at cystoscopy. Bilateral ureteral ectopia (3dogs) and unilateral +/- bilateral ectopia (1 dog) was diagnosed by excretory urography.Neither urethrography nor excretory urography demonstrated the exact site or method ofureteral implantation. Sonography was inconclusive for ectopia in all 4 dogs. Aninaccurate sonographic diagnosis of unilateral ureterocoel was made in 2 dogs.

Conclusion: Preliminary results suggest that contrast-enhanced CT is superior to otherdiagnostic imaging modalities for the identification of ureteral ectopia in the dog.Contrast-enhanced CT was also determined to be useful in localizing the site and methodof ureteral implantation in affected dogs.

MAGNETIC RESONANCE CONTRAST—A REVIEW AND UPDATE.K.A. Buckwalter MD, MS and W.R. Widmer, DVM, MS

Purdue University, W Lafayette, IN and Indiana University School of Medicine, Indianapolis, IN___________________________________________________________________________

The basic premise of MR image contrast is that one can observe signals from therelaxation of excited protons in tissues. There are two different signal perspectives: T1 relaxation(longitudinal plane) and T2 relaxation (transverse plane). (1,2) Mobile protons in water and lipidsare subject to RF excitation and are responsible for the bulk of the MR signal. Protons in nucleicacids, proteins and bone have limited mobility and do not contribute significantly to the MRimage. Much of the water in tissue is loosely bound (hydrated) to macromolecules and relaxesquickly following excitation. Free (bulk) water relaxes more slowly following excitation.

Differences between T1 and T2 relaxation times of soft tissues are emphasized by choiceof TE, TR and, depending on the pulse sequence, the flip angle. MR images can be “weighted”toward T1 or T2 relaxation; however, any MR image has contribution from each kind ofrelaxation. With conventional spin-echo imaging, using short TR and TE, T1 weightingpredominates and tissue signal intensity is inversely proportional to T1 relaxation time: long T1tissues like free water are dark and short T1 tissues like fat are bright. Using long TR and TE, T2weighting predominates and tissue signal intensity is proportional to T2 relaxation time: freewater is hyperintense (long T2), fat has intermediate intensity (intermediate T2) and muscle ishypointense (short T2). An MR image is proton density-weighted when TE, TR and flip angleare not set to maximize T1 or T2 differences. Proton density-weighted images reflect theunderlying distribution of lipid and water protons and tend to have a short scale of contrast.

Many pathologic processes are associated with a local increase in free water. Thus, anyimaging technique that emphasizes free water while de-emphasizing the signal from surroundingtissues increases the visibility of disease. Selection of the appropriate imaging parameters iscritical in the clinical use of MR. In addition, pulse sequences can be altered to change imagecontrast. For example, inversion recovery methods can be used to null the signal from a specifictissue, such as fat or CSF, allowing detection of underlying signal from water. Fat nulling allowsrecognition of marrow edema while CSF nulling permits assessment of periventricular edema.

Magnetization transfer imaging (MTC) alters contrast by suppressing the backgroundsignal from proteinaceous tissues. (2,3) This is a complex phenomenon produced by adding an off-resonance RF pulse to a standard MR pulse sequence. The off-resonance pulse is absorbed bywater bound to macromolecules in the tissues; the free water that normally contributes to the MRsignal does not directly absorb this RF energy. Instead, because of interactions between the twowater types, the bound water transfers some of the absorbed energy directly to the free water inthe surrounding tissue. This transfer of energy ("magnetization") is responsible for generation ofdifferential tissue contrast. The saturated tissue cannot participate in the formation of the MRimage and signal intensity is reduced. MTC is employed to improve the contrast of brain,muscle and parenchymal organs of the abdomen.

Exogenous contrast is afforded by paramagnetic contrast media. T1 contrast agents arewidely used for studying the CNS and are important in detecting tumors and infections.

MRI is a very powerful imaging technique. There have been dramatic changes during thepast two decades both in the development of imaging sequences as well as the variety of relevantclinical applications. Helical CT is a strong competitor in this regard, although it typically cannotprovide the contrast resolution of MR imaging.

1) Elster AD, Mosby, 1994, 2) Wherli, FW, McGowan, Lippincott, 1996, 3) NesAvier,M, Univ MD, 1996

FRAMELESS STEREOTACTIC RADIOSURGERY FOR TREATMENT OF TUMORSOF THE HEAD IN SMALL ANIMALS. N.V. Lester BVMS, L.E. Fox DVM, K. CookeDVM, R.C. Clemmons DVM, C. L. Chrisman DVM, C. L. Mariani DVM, F. J. Bova Ph. D.*Dept of Small Animal Clinical Sciences, College of Veterinary Medicine and Department ofNeurosurgery, College of Medicine*, University of Florida, Gainesville, FL 32606.

INTRODUCTION: Radiosurgery was developed by neurosurgeons, radiation oncologists andphysicists working together in the therapy of brain tumors in people. The technique delivers asingle high conformal dose of radiation to the target, with steep dose gradients resulting inminimal dose to the surrounding normal tissues. It is considered a standard treatment option forcertain CNS abnormalities, including primary and metastatic brain tumors. Framelessradiosurgical methods were developed in people to facilitate fractionation of the dose whencircumstances (tumor size, location or radiobiology) prohibited delivery of a single large dose ofradiation, and have proven easy to use in animals. We report on the use of stereotacticradiosurgery for the treatment on tumors of the head region, both intra- and extra-cranial, insmall animals.METHODS: A custom bite plate is fitted to the patient’s dentition at the time of CT scan. Areference array composed of six infrared light emitting diodes (IRLED) is rigidly fixed to thebite plate for both imaging and treatment. For most tumors an MRI scan is also acquired, and theimage sets are fused to facilitate computerized treatment planning. Treatment is performed withthe patient under general anesthesia. A ceiling mounted infra-red detecting camera localizes eachof the IRLED’s in space, defining the bite plate position in reference to the isocenter of the linearaccelerator to which the camera is calibrated. The linear accelerator is mounted on a rotatinggantry; radiation is delivered to the target (defined as the contrast-enhancing region) in a seriesof non-coplanar arcs. An isocentric stabilization subsystem reduces translational and rotationalerror to less than 0.2 mm. All patients received 1250 to 1750 cGy as a single dose.RESULTS: Fifteen tumors have been treated by this technique. Intracranial tumors include 4confirmed and 1 suspected but not confirmed meningioma(s), 2 of which were debulkedsurgically. Of the 5 dogs with brain tumors, 2 are alive and doing well (19m, 15m), 1 died ofunrelated causes, 1 died from complications within 24 hours of treatment, and 1 respondedpoorly and was euthanased at 7m. Reasons for the death of 1 dog and the poor response of 1 dogfollowing brain tumor irradiation are unclear. Extracranial tumors include 7 which involved thenasal cavity &/or frontal sinuses (1 ACA, 1SCC, 2 OSA, 1 CSA, 2 LSA), 1 oral SCC, 1periorbital myxosarcoma and 1 multilobular tumor of bone. The latter 2 cases had multiplesurgical resections prior to irradiation. The follow up time is too short for meaningful data on themajority of these patients, however 1 dog with nasal ACA (20m) and 1 cat with myxosarcoma(16m) are alive with no evidence of tumor recurrence. One dog with SCC was euthanased at 7mwith metastasis, and 1 cat with nasal LSA was euthanased at 8 weeks due to apparent CNSinvolvement. Other patients are out 4 months or less with static tumors on initial recheck(s).Acute complications in extracranial cases to date have been minimal and responsive to treatment.No late effects have been noted to date.DISCUSSION: Stereotactic radiosurgery offers an alternative to conventional fractionatedradiation therapy for the treatment of certain tumors of the head region in small animals. Benefitsto the patient and owner include a single treatment session requiring less hospitalization time,and minimal complications due to relative sparing of the normal tissues. Further investigation ofdose-response and effect of tumor size and location in the case of brain tumors is warranted.

VINBLASTINE, PREDNISONE AND COARSE FRACTIONATEDRADIOTHERAPY FOR BIOLOGICALLY HIGH-GRADE CUTANEOUS MASTCELL TUMORS IN DOGS

Turek MM, Hershey AE, Thamm DH, Adams WM, Forrest LJ, Dubielzig RR, Vail DMUniversity of Wisconsin-Madison

Dogs with poorly differentiated (Patnaik grade III) mast cell tumors (MCT) have a highlikelihood of death due to disease with short reported median survival times (MST).With adjuvant vinblastine (VBL) and prednisone (PRED), a MST of 331 days can beachieved. Regional lymph node metastasis, an indication of high-grade biologicalbehavior, is also associated with a poor prognosis, irrespective of histologic grade of theprimary tumor. The objective of this retrospective analysis was to evaluate the efficacyand toxicity of combination 60cobalt radiotherapy (RT), VBL and PRED in 19 dogs withhistologically confirmed high-risk (i.e. grade II with regional lymph node metastasis orgrade III with or without regional metastasis) cutaneous MCT. All dogs received 4weekly 8-Gy-fractions of 60Co RT and chemotherapy. VBL was given at 2mg/m2 IVweekly for 4 weeks, then every other week for 4 additional treatments. Prednisone wasinitiated at 2mg/kg daily and discontinued after at least three months of tapering therapy.

Thirteen dogs had primary grade III MCT; 5 were positive for nodal metastasis.Six dogs had primary, metastatic grade II MCT. Six were treated in the gross diseasesetting. The time to treatment failure (TTF) was 398 days, comparing to a TTF of 168days for a comparable control population of dogs treated with VBL and PRED alone(p=0.17). The MST was not reached with a median follow-up of 301 days, compared toa MST of 330 days for the control population (p=0.068). Significant predictors ofprolonged TTF included incomplete surgical excision and gross disease (p<0.05).Significant predictors of prolonged MST included incomplete surgical excision, grossdisease and tumors on the limbs (p<0.05). Both TTF and MST were favorable for dogswith metastatic grade II tumors as compared to dogs with grade III tumors (p=0.072 andp=0.08, respectively). Side effects of RT were mild to moderate, depending uponlocation, and self-limiting. Overall, VBL treatments were well tolerated, with dosereductions required in only three dogs.

RADIATION INDUCED SECOND TUMOR IN DOGS IRRADIATED FOR ORALACANTHOMATOUS EPULIS.

M.C. McEntee, D.V.M1, R.L. Page, D.V.M., M.S., A.P. Théon, D.V.M., M.S.2, D.E. Thrall,D.V.M., Ph.D3. 1College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.2School of Veterinary Medicine, University of California-Davis, Davis, CA 95616. 3College ofVeterinary Medicine, North Carolina State University, Raleigh, NC 27606.

Introduction: The criteria for diagnosis of a radiation-induced second tumor have been described,and include: 1] history of irradiation and tumor development within the irradiated field, 2] latentperiod of adequate duration after irradiation before development of the second tumor, 3] for bonetumors, i.e., osteosarcoma, that develop at the irradiated site there must be documentation thatthe bone was previously normal, and 4] biopsy and histopathologic confirmation of a malignanttumor at the irradiated site. The development of a second tumor at the site of a previouslyirradiated tumor has been described in dogs after therapeutic irradiation, and in experimentalstudies. The risk of a second tumor associated with irradiation of acanthomatous epulis in dogshas been cited in support of the inadvisability of radiation in this setting with the exception ofinoperable tumors. The reported incidence of malignant tumor formation at the irradiated site indogs with acanthomatous epulis ranges from 2.6-18%. It has been stated that the risk ofpostirradiation sarcoma development may be lower after megavoltage compared to orthovoltageradiation. The purpose of this retrospective study is to review a compilation of data from twoveterinary medical teaching hospitals to more accurately assess the risk of second tumors in dogsirradiated therapeutically with megavoltage radiotherapy for oral acanthomatous epulis.

Materials and Methods: Dogs irradiated for acanthomatous epulis at North Carolina StateUniversity, and the University of California Davis were eligible for inclusion in this study. Alldogs were irradiated with megavoltage units, either Cobalt 60 or a 4 MV linear accelerator.

Results: To be presented.

Discussion : The effect of dose per fraction, treatment schedule, and type of radiation on risk ofdeveloping a second tumor in dogs irradiated for acanthomatous epulis will be discussed.

PROLONGED REMISSION AND SURVIVAL TIME IN CATS WITH INJECTION-SITE ASSOCIATED SARCOMAS USING A PRE-OPERATIVE RADIATION ANDDOXORUBICIN PROTOCOL: 61 CASES (1988-2000).

G. K. King, D.V.M., D.F. Harris, D.V.M., H. Hottinger, D.V.M., K.P. Freeman, D.V.M.,K.A. Hahn, D.V.M., Ph.D. Gulf Coast Veterinary Oncology, Houston, TX 77027.

Objective: To compare the use of pre-operative radiation and doxorubicin versus pre-operative radiation alone for treatment of cats with injection-site associated sarcomas.

Methods: In this retrospective analysis, medical records of cats referred to Gulf CoastVeterinary Oncology with histologically confirmed injection-site associated sarcomasfrom January 1988 to January 2000 were evaluated. Cats were included in the study ifthey had grossly evident and visible disease in a known injection-site sarcoma associatedlocation (i.e., interscapular) without metastases. Cats with prior tumor resection withmacroscopic recurrence were not excluded. All cats were clinically staged and computedtomography (CT) scans were performed to assist development of plans for radiationtherapy. Megavoltage radiation therapy was administered during a 7-week period, on aMonday, Wednesday, Friday schedule for a total delivered dose of 60-62 Gy.Chemotherapy, if given, was administered beginning on the day of the second radiationfraction. Doxorubicin (1 mg/kg, IV) was given every 3 weeks until 5 doses had beenadministered. Six weeks following the completion of radiation therapy and 1 weekfollowing the 5th doxorubicin treatment, macroscopic tumor resection was performed.Time to first recurrence was defined as number of days from completion of surgicalresection until recurrence of the tumor. Survival time was defined as number of daysfrom surgical resection until death. Complete staging was performed every 3 monthsafter completion of treatment. Curves for time to first recurrence and survival weregenerated by use of Kaplan-Meier product limit method. Data were censored if cats werefree of disease, lost to follow-up, or died of disease unrelated to the sarcoma diagnosis.Differences between curves were analyzed by applying the log rank test. Multivariateanalysis was performed to determine the possible influence of pre-operative tumor size,tumor location, and other patient-related and treatment-related variables. Significancewas established at p < 0.05.

Results. Sixty-one cats were included in the study. Thirty-one cats had radiation andsurgery alone, 30 cats had radiation, doxorubicin and surgery combined. Cats whoseprotocol included doxorubicin had a significantly longer remission time (median 360days; range, 54 to 1,347 days) than those cats whose protocol did not include doxorubicin(median 162 days; range, 31 to 1,575 days). No difference was found in survival timebetween the two groups of cats (median 413 days for cats with doxorubicin; median 330days for cats without doxorubicin).

Discussion/Conclusions: Cats presenting with macroscopic injection-site associatedsarcomas have a significantly longer duration of remission when doxorubicin is includedin the pre-operative radiation protocol.

Evaluating Contrast Enhanced Ultrasound as a Method for Clinical Monitoring of TumorAngiogenesis in a Rat ModelRE Pollard, JE Chomas, ER Wisner, SM Griffey, KW Ferrara.University of California, Davis. Davis, CA 95616PURPOSE: To serially monitor the growth rate and vascularity of induced tumors in rats usingcontrast enhanced ultrasound and to compare imaging data with correlated histologic sections.METHOD AND MATERIALS: R3230 rat mammary adenocarcinomas were implanted within thesubcutaneous tissues of the thigh. Rats were first imaged 28 days following implantation andserially every 3-4 days until day 42. Sonographic evaluation was performed using a 5.0 MHz lineartransducer and modified Siemens Sonoline Elegra. Measurement of maximum tumor height, widthand length were obtained. A constant rate infusion of ultrasound contrast media was deliveredintravenously. Contrast was diluted to100ul/ml and delivered at 10 ml/hour for a maximumvolume of 3 ml's. Imaging commenced 2 minutes after the onset of infusion using a destruction re-perfusion mode. A destructive pulse was fired first, followed by a chain of sequential, non-destructive pulses that allowed for visualization of vascular contrast re-perfusion. All otherparameters were kept constant. Six regions of interest (ROIs) were identified within the tumor andplots of intensity change over time were generated. On day 42, CT images were obtianed precontrast and serial CT images obtained post contrast at 2 second intervals for 1 minute immediatelyfollowing the ultrasonic examination. The imaging planes mimicked the sonographic planes.ROI's were drawn in the same general areas as the ultrasound ROI's. Rats were then euthanizedand tumor tissue excised. Tissue was preserved in 10% formalin and sections obtained in the sameorientation as the ultrasound and CT images. Sections were prepared with H & E stain to evaluateoverall morphology. Factor VIII and CD 31 immunostained sections were obtained to localizemature and new vessels.RESULTS: Serial contrast-enhanced ultrasound images revealed progressive change from adiffuse vascular network in the earlier stages to a peripheral distribution of vessels. Ultrasound-generated intensity maps acquired on the final day of imaging showed close correlation betweenregional intensity, early rim enhancement demonstrated on CT images and histologic vesseldensity. Neovessels identified with CD 31 staining were visualized with contrast-enhancedultrasound and the neovessel density showed good correlation with the regional intensity changes.CONCLUSIONS: Serial contrast-enhanced destruction re-perfusion ultrasound imaging ofsubcutaneously implanted tumors provides an accurate assessment of regional blood flow.Intensity maps generated through ROI analysis show good correlation between intensity changeand vascular density. Neovessels appear to be well visualized.The assistance of Pat Sutcliffe, Steve Sessa, Liexiang Fan, Pat Von Behren, Wayne Gueck andZuhua Mao of Siemens Inc., Issaquah, WA, is gratefully appreciated. The authors acknowledge thesupport of NIH CA76062.

PERFUSION MEASUREMENTS IN THE NORMAL CANINE KIDNEY FOLLOWINGBOLUS INJECTION OF CONRAST AGENT. K. R. Waller. BS. , R. T. O’Brien. D.V.M., J. A.Zagzebski. Ph.D., H. Tu. MS. University of Wisconsin-Madison, School of Veterinary Medicineand University of Wisconsin-Madison, Medical School. Madison, WI 53706

Introduction :Assessments of perfusion using ultrasound have previously relied upon power Doppler or

color flow measurements. Ultrasonographic contrast agents provide an additional resource formeasurements of perfusion using ultrasound. In a previous abstract, we measured fundamentalmode attenuation and backscatter coefficients of the liver following bolus injection of contrastagent. The present study uses harmonic imaging of the canine kidney following bolus injection ofcontrast agent to determine normal infusion rates of contrast agent in the canine kidney. PowerDoppler images without contrast agent administration were collected for comparison to harmonicimages following contrast agent administration.Methods :

The left kidneys of seven adult dogs were imaged in power Doppler, “harmonic angio”,and a single-pulse harmonic mode on a GE Logiq 700 scanner. Bolus intravenous injections ofDefinity (DuPont Pharmaceuticals) were administered while imaging in harmonic angio and single-pulse harmonic modes.

Power Doppler: Images were produced using either the 348C probe (CF=3MHz) or theLA39 probe (CF=7MHz). Images were collected on an internal magneto optical drive.

Harmonic Angio: A 348C probe in harmonic angio mode, which relies upon harmonicechos and changes in position of contrast agent to provide a signal, was used collect flash imagesat a Mechanical Index of 0.8. While a 0.05 ml bolus intravenous injection of Definity wasadministered, the ultrasound was frozen for approximately 45 seconds. The ultrasound wasunfrozen, and the first three frames were collected on the internal magneto optical drive. Theprocess was repeated three times. Mean pixel values from a region of the cortex and medulla weremeasured with NIH image. The slope of the mean pixel value versus time was determined for eachregion.

Single-Pulse Harmonic: A 348C probe in “high harmonic mode”, Mechanical Index of 0.3,1 Hz frame rate, was utilized to collect images following a 0.05 ml bolus intravenous injection ofDefinity. Imaging began with contrast agent injection and continued for 90 seconds. A computerwith a frame grabber board collected the images. A region was selected in the renal cortex ormedulla and mean pixel values were measured using NIH Image. Mean pixel values versus timewere plotted for each region. The slope, or rate of mean pixel value change, was calculated fromthe area of the chart encompassing 10% above the minimum mean pixel value to 90% of themaximum mean pixel value.Results :

Single-pulse harmonic images of the kidney resulted in a slope of 7.88 mean pixelunits/second (5.25) in the cortex and 2.58 mean pixel units/second (1.30) in the medulla. Meanpixel values in harmonic angio mode were reduced by 26.5% (6.7%) and 25.2% (5.6%) betweenframes 0 and 1 and frames 1 and 2 respectively. Harmonic angio and high harmonic imagesallowed for improved visualization of perfusion in the renal cortex than power Doppler.Discussion :

The use of contrast agent in a harmonic mode allows for better visualization and assessmentof perfusion in the kidney than power Doppler, but may not be a total replacement. The numberand placement of focal zones will have an effect on measurements of mean pixel values made inharmonic modes.

Future studies should address the viability of contrast enhanced harmonic imaging as ameans of detecting disease in the kidney.

QUANTITATIVE EVALUATION OF CONTRAST ENHANCEMENT OFCANINE LIVER USING HARMONIC ULTRASOUND IMAGINGL.E. Ziegler. D.V.M, R.T. O’Brien. D.V.M., K.R. Waller. B.S., J.A. Zagzebski. Ph.D.University of Wisconsin-Madison, School of Veterinary Medicine and Department ofMedical Physics (Zagzebski), Madison, WI 53706

Introduction: Because of the increased sensitivity of contrast harmonic imaging, tissueperfusion on a capillary level can be detected using these agents. The purpose of thisstudy is to determine normal perfusion dynamics in the canine liver.Methods: Five healthy adult beagles were imaged under general anesthesia. In addition,three privately owned dogs with no evidence of liver disease were imaged withoutanesthesia. A 4-9 MHz broadband curvilinear transducer and harmonic capableultrasound system were used for all imaging.1 Adjustable parameters such as depth, gain,and focal zones, were kept constant for all patients. Images were digitally captured on anexternal computer.2 Three different methods of evaluating perfusion were applied.

First, 0.05 cc of a microbubble contrast agent3 were administered via anindwelling cephalic venous catheter. Images were obtained at a rate of one frame per 3seconds, for three minutes after bolus injection. Second, a constant rate infusion (CRI) ofa dilute solution of the same agent (0.8 cc of agent in 50 cc of saline, at 2 cc/min) wasperformed. Images were again obtained every 3 seconds for three minutes after the CRIwas begun, then for an additional 3 minutes after the CRI had been discontinued.Thirdly, a higher mechanical index mode at a frame rate of 41 Hz was used during bolusinjections to produce “flash echo” images. Imaging was discontinued for approximately2 minutes to allow accumulation of contrast agent, and then activated again. Using thecine loop function, the first three frames after re-activation were captured.

Regions of interest (ROI’s) were manually drawn as close as possible to the singlefocal zone, near the middle of the image. The ROI was drawn as large as possiblewithout including structures such as the diaphragm, large vessels, or gall bladder. Thesame ROI was used for each bolus injection, CRI, or set of 3 flash echo frames. Meanpixel values were then plotted against time (bolus and CRI) or frame number (flashecho).Results: For the bolus injections, inflow slopes averaged 3.52±1.57 and outflow slopesaveraged –0.66±0.33. For the CRI, inflow slopes averaged 0.33±0.34 and outflow slopesaveraged –0.16±0.16. Flash sequences had an average slope of –26.5±6.7 and an averagepercent difference in Mean Pixel Value of 99.3%±55.5%. Agreement was better betweenmultiple trials in one patient than between patients. Subjectively, the plots for the CRIwere most variable both within and among subjects, and it was often difficult todetermine beginning and end points of slopes.Discussion: This study demonstrates inflow and outflow slope characteristics ofultrasound contrast perfusion in dogs with normal livers. These values may serve as thebasis for comparison in dogs with diffuse liver disease affecting perfusion such asportosystemic shunting and portal hypertension.

1 GE Logiq 700 with 548c transducer, Milwaukee Wisconsin2 PowerMac 8100, Apple Computer, _______, California3 Definity, Du Pont Merck, Wilmington, Delaware

RANGE AMBIGUITY ARTIFACT IN CLINICAL ULTRASOUNDR.T. O’Brien, J.A. Zagzebski, F. DelaneyUniversity of Wisconsin-Madison, School of Veterinary Medicine, Department ofSurgical Sciences, Madison, WI 53706.

An artifact was noted in the urinary bladder of a 12 year-old Springer Spaniel doghaving an ultrasound examination to look for a sonographic cause of systemichypertension. Imaging was performed with a medium frequency (7.5 MHz) curvilineartransducer, six focal zones, 10 cm depth of field and frame rate of 12 hertz. Duringsonographic evaluation an indistinct echogenic curvilinear line and image of intestineswas seen in the lumen of the urinary bladder. The artifact was progressively reduced bydecreasing the number of focal zones and eliminated by applying only 1 focal zone.Application of identical system settings to image water in a plastic container resulted in asimilar artifact.

To produce an ultrasound image, the scanner transmits ultrasonic pulses indifferent directions and detects and displays echoes from tissue interfaces. After eachtransmit pulse, sufficient time must be allocated for echoes to return to the transducerfrom the maximum depth imaged before a subsequent transmit pulse is launched. If thisis not done, “range ambiguities” arise, caused by simultaneous detection of echoes fromdeep structures, arising from the previous transmit pulse, and echoes from shallowstructures insonified by the present pulse. To retain modest frame rates when multipletransmit focal zones are deployed, equipment manufacturers have designed transmitpatterns that partially do away with the pulse repetition frequency limitation, allowingsubsequent transmit pulses to be emitted before echoes from the previous transmit pulsearrive at the transducer.

Range ambiguity is also associated with Doppler imaging.

Similar to themanifestation during B mode imaging in animals, concurrent high pulse repetitionfrequency and large depth of field may result in an artifact in the near field. With pulsedDoppler, placement of the range gate in the distal field in high pulse repetition frequencymode results in the appearance of a “ghost” range gate in the near field. These “ghost”range gates can detect Doppler shift frequencies and the composite of shift frequenciesappear in Doppler spectral display. Elimination of the artifactual gate, and concurrentunwanted Doppler shift information, requires alteration of the range gate location,selection of a lower velocity scale, or switching to a lower pulse repetition frequencysetting. The pulse repetition frequency is often directly adjustable in Doppler modes onmany machine systems, or it is adjusted when the operator changes the velocity scalesetting. Lowering the pulse repetition frequency increases the likelihood of aliasing bylowering the Nyquist Limit.

If the artifact is suspected during B mode imaging adjusting pulse repetitionfrequency on those machines that have this feature helps eliminate the artifact. Reducingthe number of focal zones may reduce the artifact on those systems with transmit patternsthat do not strictly follow the pulse repetition frequency limitation. If “ghost” Dopplerrange gates are noted during pulsed Doppler imaging, reducing the range gate location orswitching to low Doppler scale setting can help eliminate the artifact.

SONOGRAPHIC FINDINGS IN DOGS AND CATS WITH INTESTINALPERFORATION: A RETROSPECTIVE STUDY (1995-2001)SR Boysen, DVM, AS Tidwell, DVM, DG Penninck, DVM. Tufts University School ofVeterinary Medicine, North Grafton, MA

Introduction: Gastrointestinal (GI) perforation is a common cause of septic peritonitis, and canbe a life threatening emergency, requiring aggressive and intensive surgical and medicalintervention. Pre-surgical confirmation of GI perforation is challenging, and has previouslyrelied on the detection of pneumoperitoneum on plain film radiographs, or leakage of contrastmedium on an upper GI series. The purpose of our study was to characterize the sonographicfindings in dogs and cats with confirmed GI perforation.Methods: A retrospective clinical study was performed to evaluate the sonographic features ofGI perforations in dogs and cats by reviewing the log book of ultrasound examinationsperformed between 1995 and 2001. Patients were included in the evaluation only if GIperforation was confirmed by surgery or necropsy. The sonographic images and reports andabdominal radiographs and reports were reviewed by the investigators. The sonographic studieswere assessed for the presence of bright mesenteric fat; abdominal effusion; free gas; GI fluidaccumulation and altered motility; changes in GI wall thickness, layering and echogenicity;pancreatic changes; presence of mass or foreign body; lymphadenopathy; and whetherperforation was listed as a differential diagnosis in the report. When available, the radiographicstudies were assessed for loss of serosal detail; presence of free air, mass, foreign body, orobstruction; and whether a perforation was listed as a differential diagnosis in the report.Results: Sixteen animals (11 dogs and 5 cats) were evaluated. Sonographic findings includedregional bright mesenteric fat (16/16), free peritoneal effusion (13/16), fluid filled stomach orintestines (9/16), lymphadenopathy (8/16), loss of GI wall layering (6/16), presence of free air(5/16), changes in GI wall thickness (4/16), pancreatic changes (3/16), reduced GI motility(3/16), corrugated intestines (3/16), presence of a mass (4/16), presence of a foreign body (2/16),and mineralization of the gastric wall (1/16). In 11/16 cases, perforation was listed as adifferential diagnosis by the sonographer. There were radiographs and radiographic reportsavailable for 11 of the cases. Radiographic findings included decreased serosal detail (9/11), freeair (6/11), and suspected foreign body (1/11). GI perforation was listed as radiographic diagnosisin 5/11 cases, all of which had evidence of pneumoperitoneum. One patient, not initiallydiagnosed with pneumoperitoneum, was retrospectively found to have free air on abdominalradiographs. In the 11 cases with radiography, GI perforation was listed as a sonographicdiagnosis in 6 cases (6/11). In 3/5 cases where free air was diagnosed sonographically,radiographs were either not available (2/5) or were misinterpreted on presentation as lacking freeair (1/5). Peritoneal fluid analysis was performed in 9/16 cases, 5 of which were identified asseptic inflammation, the remaining 4 were classified as neutrophilic inflammation with noetiologic agent identified. The histologic or surgical diagnoses were as follows; peg tube siteleakage, duodenal adenocarcinoma, ileocolic lymphoma, 3 intestinal surgical dehiscence,hairball, worm impaction, and in 8 cases a focal area of gastric/intestinal ulceration or transmuralnecrosis with perforation was identified without evidence of an underlying cause.Conclusions: Ultrasonography appears to be a useful tool for the diagnosis of GI perforation.Our study found direct evidence of GI perforation (free air) in 5 of 16 cases, and indirectevidence in all 16 cases examined. In the appropriate clinical setting, these sonographic findingswarrant confirmation of GI perforation through abdominocentesis or exploratory surgery.

UNEXPECTED FINDINGS IN COMPLETE VERSUS PARTIAL ABDOMINALULTRASOUND EXAMINATIONS. G.A. Henry., A. Bahr., S. Shull. Texas A&M University.College Station, TX 77843

Ultrasound examination of the small animal abdomen is an increasingly common procedure insmall animal disease diagnosis. Experience suggests that examination of the entire abdomen ispreferable over the examination of selected organs or organ systems within the abdomen. Manysonographers are faced with requests for limited abdominal ultrasound examinations based onthe following common reasons: 1) clinical data suggest disease in only one organ system, 2) costconcerns result in request for lower cost limited exam, 3) previous exam revealed disease in onlyone organ system, 4) limited exam requires less time. Some sonographers have raised singleorgan exam prices to make an examination of the entire abdomen more attractive from a cost/benefit ratio. This study was undertaken to quantify the incidence and potential significance ofunexpected findings in the ultrasound examination of small animal abdomens.

Data for the study was collected on individual forms following each abdominal ultrasoundperformed at the Texas A&M University Small Animal Clinic between May 17, 2000 andJanuary 22, 2001. An unexpected finding was defined as any sonographic abnormality thatwould not have been observed if the examination was confined to the organ or organ systems ofinterest as defined by the exam request. The entire abdomen was examined even in cases withpartial exam requests. The clinical significance of the unexpected findings was categorized assignificant, insignificant or of unknown significance. Significant findings were defined asfindings compatible with a clinical disease that would alter treatment or prognosis. Other datarecorded included specific sonographic abnormalities, requested study, sonographer, clinician,signalment, history and physical exam findings.

A total of 785 abdominal exams on canine and feline patients were performed in the study timeperiod. Examinations of the entire abdomen were requested for 725 (92.4%) of the total exams.Preliminary data analysis indicates unexpected findings in 228 (29%) cases. Of these 228 cases,133 (58.3%) were considered clinically significant. The remaining 95 (41.7%) cases wereconsidered clinically insignificant or of unknown significance. Therefore, clinically significantunexpected findings were observed in 133 (16.9%) of the total 785 cases. Further analysis of thedata is pending.

This study suggests that ultrasound examination of the entire abdomen should be encouraged.Unexpected ultrasound findings resulted in altered treatment and/or prognosis of patients in over16% of the cases examined. These findings would likely have not been identified with anabdominal exam limited to the primary organ(s) of concern to the attending clinician. Themajority of our small animal requests are for the entire abdomen. One factor resulting in thislarge number of entire abdomen exams is that clinicians are interested in evaluations formetastatic disease. In our clinic the cost of examining the entire abdomen is not significantlyhigher than the cost for a limited exam in order to encourage complete exams. In our opinion,this study suggests an unacceptable rate of missed significant findings will occur in limitedabdominal ultrasound exams. The results of this study give a quantitative value that may beuseful in evaluating abdominal scanning protocols, especially in situations when single organs ororgan systems are of primary clinical concern.

COMPARISON OF THORACIC ULTRASONOGRAPHY AND RADIOGRAPHY IN 17FOALS WITH RHODOCOCCUS EQUI PNEUMONIA. Sammy Ramirez, DVM, MS, Guy D.Lester, BVMS, PhD, Greg R. Roberts, DVM, MS. College of Veterinary Medicine, NorthCarolina State University, Raleigh, NC and School of Veterinary Medicine, University ofFlorida, Gainesville, FL.

Introduction: Rhodococcus equi (R. equi) pneumonia is a well-recognized condition of foalsbetween 1 and 6 months of age. Infection manifests primarily as an insidious pyogranulomatouspneumonia. Confirmation of R. equi pneumonia usually requires isolation of R. equi viatranstracheal aspiration and radiographic evidence of pulmonary abscesses. Becauseradiographic examination may be limited by patient size or location (in the field or the intensivecare unit), a clinically efficient alternative diagnostic imaging technique for evaluating the lungsof potentially infected foals may be beneficial to equine veterinarians. Routine ultrasonography,which has become more common in veterinary medicine because it is noninvasive andeconomical, may be a viable alternative. Ultrasonography is generally considered to be aninsensitive test for this condition because of its inability to detect lesions located deep to normal,aerated lung. However, it has been suggested that the lung periphery is often affected in mosthorses and foals with pulmonary abscessation enabling these lesions to be identifiedultrasonographically. The objective of this retrospective study was to determine the clinicalusefulness of thoracic ultrasonography, when compared to thoracic radiography as the “goldstandard”, for evaluation of foals with R. equi pneumonia.

Materials and Methods: Medical records of 48 foals with a diagnosis of R. equi pneumoniaexamined at the University of Florida Veterinary Medical Teaching Hospital between 1997 and1999 were reviewed. Foals were included in the study if 1) R. equi was isolated from atranstracheal aspirate and if 2) thoracic radiographs and 3) thoracic ultrasound examination wereperformed at the time of hospital admission. Seventeen foals met these criteria and their medicalrecords were examined. All diagnostic ultrasound examinations were performed using a multi-frequency mechanical sector scanner with a 5.0 or 7.5 MHz transducer.

Results: All foals evaluated were between 4 weeks and 5 months of age. Pyogranulomatouspneumonia was identified in 13 foals radiographically. Severe consolidative pneumonia with nodetectable abscessation was radiographically identified in 3 others. Both consolidation andabscessation was radiographically identified in one. In this foal only consolidation wasultrasonographically identified. Ultrasonographically, pulmonary abscessation was identified in12 foals and pulmonary consolidation with no detectable abscessation was identified in 3 others.Sonographic examination detected only pleural irregularities in one foal, which was subsequentlyfound to have pyogranulomatous pneumonia radiographically.

Conclusion: Based on this study, the association between radiography and ultrasonography inidentifying pulmonary pathology in foals with R. equi is high. Because ultrasonography is easyand clinically efficient, this technique is advocated as a “screening” technique to evaluate foalssuspected to be infected with R. equi when thoracic radiography is unavailable.

ULTRASONOGRAPHIC FEATURES OF CANINE ABDOMINAL MALIGNANTHISTIOCYTOSIS. Sammy Ramirez, DVM, MS, James P. Douglass DVM, MS, Ian D.Robertson, BVSc. College of Veterinary Medicine, North Carolina State University, Raleigh,NC 27606.

Introduction: Malignant histiocytosis (MH) is an uncommon neoplastic process characterizedby progressive, systemic invasion of multiple organs by morphologically atypical histiocytes.The spleen, liver, bone marrow, and lymph nodes are commonly affected. This disease primarilyaffects middle-aged, male dogs. There is a familial predilection in Bernese mountain dogs, butno such predisposition is known to occur in other commonly affected breeds includingRottweilers, and Golden Retrievers. Clinical signs are non-specific and include fever, lethargy,anorexia, weight loss, and generalized lymphadenopathy. Radiographic abnormalities includepulmonary nodules and/or consolidation, mediastinal mass(es), pleural effusion, and/orhepatosplenomegaly. There is little published information regarding the ultrasonographicappearance of MH in dogs. This study presents the abdominal ultrasonographic features of 16dogs with confirmed MH.

Materials and Methods: The medical records of the College of Veterinary Medicine, NorthCarolina State University were searched for canine patients that had been diagnosed with MHand had received a concurrent abdominal ultrasound examination. Sixteen dogs were identified.In each dog, MH was diagnosed via biopsy or fine needle aspirate (FNA) of the spleen, liver,abdominal or peripheral lymph nodes, bone or bone marrow. The medical records, ultrasoundreports and sonograms were reviewed. Necropsy examination findings were available for 10dogs.

Results: The dogs were between one and 12 years of age. There were 10 males and 6 females.Breeds included Bernese mountain dog (3), Rottweiler (1), Flat-coated retriever (3), Goldenretriever or Golden retriever mix (4), Shar-pei (1), Scottish terrier (1), Labrador retriever (1),Cocker spaniel (1), and Springer spaniel (1). The most common ultrasonographic finding washypoechoic nodules in the spleen, some of which caused distortion of the splenic margin. Theliver was the second-most common organ affected. Hepatic ultrasonographic features werehighly variable, including hypoechoic, hyperechoic or mixed echogenic lesions. Other commonultrasonographic abnormalities included hypoechoic nodules in the kidneys and mesenteric andmedial iliac lymphadenopathy.

Conclusion: The most commonly affected organs in this study were the spleen, liver and lymphnodes. Hypoechoic nodules were the predominant finding in the affected spleen and kidney,while liver abnormalities were highly variable (hypoechoic, hyperechoic or mixed echogenicmasses). The results of this study suggest that the ultrasonographic appearance of canine MH isnonspecific. Definitive diagnosis requires cytologic or histologic examination. Whenhypoechoic nodules are present in abdominal organs, especially the spleen, MH should be addedto the list of differential diagnosis.

HEREDITARY MULTIFOCAL RENAL CYSTADENOCARCINOMAS AND NODULARDERMATOFIBROSIS: ASSESSMENT OF US SENSITIVITY FOR EARLY DIAGNOSIS

N. Ottesen. D.V.M., L. Moe. D.V.M., Ph.D., R.Heggebøe *. D.V.M, T. Jonasdottir# . D.V.M.Department of Small Animal Clinical Sciences, Norwegian School of Veterinary Science,P. O. Box 8146 Dep., N-0033 Oslo, Norway. *Department of Pathology, National VeterinaryInstitute, P.O. Box 8146 Dep., N-0033 Oslo, Norway. # Department of Morphology, Genetics andAquatic Biology, Norwegian School of Veterinary Science, P. O. Box 8146 Dep., N-0033 Oslo,Norway.

IntroductionCanine hereditary multifocal renal cystadenocarsinoma and nodular dermatofibrosis (RCND) is arare, naturally occurring inherited cancer syndrome observed in German Shepard dogs. TheRC/ND syndrome expresses in an autosomal dominant manner. The renal cystadenocarsinoma ischaracterized by bilateral multiple cysts and masses in the kidneys. The diagnosis of RC/NDsyndrome is usually made when the dogs are middle aged. The late occurrence of clinicalsymptoms is difficult from a breeding point of view.The purpose of the study was to estimate the sensitivity and specificity of ultrasonography (US)in the diagnosis of RC/ND syndrome by detecting small renal cysts, as compared with necropsyresults.MethodsA renal US and necropsy was performed in 14 mixed breed puppies (mother unaffected -andfather affected with RC/ND). The puppies underwent renal US between 12 and 13 weeks of age.The study included 7 female and 7 male dogs. After completing the renal US the dogs wereeuthanized and underwent necropsy. The sensitivity of US for diagnosis was estimated bycomparing the US results with necropsy results – including macroscopic and histopathologicalexaminations. Diagnosed renal cysts on US and necropsy were recorded as positive findings.ResultsFive (36%) of 14 puppies had positive renal findings.The renal sonographic features in positivepuppies included multiple small cysts of different sizes (1 – 3 mm), in normal-sized kidneys,normal cortical echogenicity and conserved corticomedullary differentiation. US demonstrated asensitivity of 80 % and a specificity of 100 %. The positive –and negative predictive values were1 and 0.9, respectively.ConclusionUS is a imaging technique that should be used in the diagnosis of RC/ND syndrome.Consequently, puppies of dogs with known or suspected RC/ND syndrome can be identified aspresymptomatic by ultrasonography and detection of small cysts may serve as a marker of earlydisease and prevent the dog from being bred.

PUBIC SYMPHYSIODESIS IN 22 PUPPIES: CT AND RADIOGRAPHIC RESULTSAT TWO YEARS OF AGE.

W.M. ADAMS DVM, R.T. DUELAND DVM, A.J. PATRICELLI DVM, J.P.FIALKOWSKI MS. Dept. of Surgical Sciences, School of Veterinary Medicine,University of Wisconsin, Madison, WI 53706

Introduction: Juvenile pubic symphysiodesis (JPS) has been shown to increaseventrolateral rotation of the acetabulae when performed on puppies 12 to 24 weeks ofage. JPS was performed on puppies that had radiographic evidence of excessive jointlaxity, with the intent of improving coxofemoral conformation and function later in life.The purpose of this study was to document hip skeletal changes at maturity, in dogs thathad early closure of the pubic symphysis as a result of JPS.

Method: Puppies between the ages of 12 and 24 weeks received either JPS viaelectrocautery (N = 22) or had a sham procedure as controls (N = 6). Acetabular anglewas measured and appearance of the pubic symphysis was documented by CTimmediately prior to JPS, at one year of age and again at 2 years of age. Distractionindices (DI - PennHip method) and Norberg angles were measured and hip conformationand degenerative changes were documented radiographically at all 3 ages for each dog.

Results: Preoperative DI range for JPS dogs was 0.41 – 1.09; the range at two years was0.03 – 0.87. JPS resulted in significantly improved acetabular angles, distraction indicesand Norberg angles. Degrees of angle improvement varied inversely with the age of thepuppy when JPS was performed. Modeling of the pelvis in response to JPS was readilyobserved by imaging techniques. Radiographic indication of complete pubic symphysealablation was inconsistent at one year, but was not necessary to document modeling effect.Ablation of the pubic portion of the symphysis was attained in all JPS dogs by two years.DJD occurred in all hips having an initial DI > 0.7 (N=7). None of the hips with initialDI < 0.55 developed moderate or severe DJD. Mild or moderate DJD was evident in32% of hips in JPS dogs preoperatively. Of all hips with DI > 0.55 initially in dogswhich had the JPS procedure, 39% developed moderate or advanced DJD by two years ofage. None of the control hips had DJD preoperatively. This contrasted with a 60%incidence of moderate to advanced DJD by two years in control hips with initial DI >0.55. Hip lameness developed in only one JPS dog, which had an initial DI of 1.09.

Conclusions: Ventrolateral rotation of canine acetabulae resulting from JPS was welldocumented by imaging techniques. Age at the time of symphysiodesis had a significanteffect on CT and radiographic parameters of pelvic modeling. JPS reduced the incidenceof moderate to severe DJD. JPS may reduce lameness incidence associated withdegenerative arthrosis of hip dysplasia.

THE FEASIBILITY OF STANDING EQUINE MRI: WORK IN PROGRESSA.L. McKnight, DVM*, D.K. Baird, DVM, PhD*, D.M. Nunamaker, VMD*, P.J. Rossman, MS**,

R. Grimm, MS**, E.B. Welch, BS**, A. Manduca, Ph.D**, R.L. Ehman, MD***University of Pennsylvania New Bolton Center, Kennett Square, PA. ** Mayo Clinic, Rochester, MN.

Introduction -- Magnetic resonance imaging of the lower limbs of the equine athlete is limitedby available magnet designs and the requirement of general anesthesia. An open-bore magnetcould be designed to accommodate the limbs of a standing, sedated horse. Standing equine MRImay be subject, however, to swaying motions of the lower limbs occurring during the exam.This motion could corrupt the images and render them non-diagnostic. Newer developments inMR motion correction algorithms offer the prospect of generating diagnostic-quality imagesfrom motion corrupted scans.

The objective of this work is to observe and quantify the amount of motion expected inthe standing, sedated horse during a simulated MR exam, to apply this motion data to cadaverlimbs during MR imaging, and to study motion correction algorithms and techniques todetermine the requisite degree of correction and the feasibility of obtaining diagnostic-qualityimages.

Methods – The motions in the carpus and hock of five Thoroughbred horses were quantified asfollows. A model of a permanent magnet 0.3T MRI system designed for the standing horse1 wasbuilt. Moderate standing sedation was achieved in all five horses using acepromazine anddetomidine. The magnet model was placed around the carpus and the hock of each horse andfoam pads were inserted between the limb and the model. High-resolution 3D video motionanalysis software2 tracked four reflective markers attached to the joints with two progressivescan digital video cameras3 for up to ten minutes per joint.

A 2D MRI motion driver was built that enabled the simulation of the obtained medial-lateral and dorsal-palmar (plantar) motions in cadaveric carpus and hock specimens. A spin echopulse sequence with two navigator echoes was used to acquire transaxial images of the carpusand hock in a conventional 1.5T MRI system according to five different motion records. Tworetrospective motion correction techniques (autocorrection and navigator-based adaptivecorrection) were used to evaluate the degree of correction.

Results -- The motion records obtained from the carpus and the hock of five standing, sedatedhorses indicate significant medial-lateral, dorsal-palmar (plantar), and proximal-distaltranslational motions (up to 6.8 cm, 6.9 cm, and 3 cm, respectively). The applied medial-lateraland dorsal-palmar (plantar) motions during transaxial MR imaging of the cadaveric specimensrendered the MR images completely non-diagnostic with varying degrees of motion artifacts.Autocorrection and navigator-based adaptive correction techniques markedly improved theimage quality.

Discussion -- These results demonstrated that in-plane motions obtained from the carpus andhock of standing, sedated horses generated severe motion artifacts during transaxial MR imagingof the cadaveric specimens, but these artifacts were nearly eliminated with motion correctiontechniques. Continually improved motion correction algorithms and special pulse sequences willbe developed to further determine the feasibility of standing, equine MRI. 1 Magna-Lab, Inc., Syosset, NY.2 DMAS, Spica Technology Corporation, Kehala, Kihei, Maui, HI3 Pulnix TM6710, Pulnix America, Inc., Sunnyvale, CA.

EVALUATION OF THE URETER AND URETEROVESICULAR JUNCTION USINGSPIRAL COMPUTED TOMOGRAPHIC EXCRETORY UROGRAPHY IN NORMALDOGS LM Rozear, DVM, AS Tidwell, DVM. Tufts University School of Veterinary Medicine,North Grafton, MA 01536Introduction: The current method of choice for ureteral imaging is excretory urography (EU).Ureteral peristalsis and superimposition of the ureterovesicular junction (UVJ) by pelvicstructures and contrast medium within the urinary bladder, however, can significantly impairinterpretation of these studies. Because spiral computed tomographic (CT) images are obtainedrapidly, lack superimposition, and have superior contrast resolution, we hypothesize that the useof CT for EU (CTEU) will improve the visualization of the ureter and UVJ with minimalpreparation (i.e., without the need for cleansing enemas and urinary bladder catheterization),with shorter anesthesia times, and with a lower required volume of contrast medium. However,before this hypothesis can be tested, we felt that a trial in normal dogs using a relatively simpleprotocol was needed to describe the normal CTEU appearance of the ureter and UVJ and toidentify variations or potential pitfalls associated with the images.Methods: Six anesthetized normal dogs (2 male, 4 female) underwent helical CT scanning usingthe following parameters: 5mm collimator width, 3mm index, and pitch factor of 1.25. Pre-procedural cleansing enemas and bladder evacuation were not performed. Pre-contrast imageswere first obtained from the cranial pole of the right kidney through the ischiatic arch. A secondpre-contrast scan focused on the urinary bladder (from apex to ischiatic arch) was thenperformed using a smaller displayed field of view (FOV). A post-contrast scan extending fromthe right kidney to ischiatic arch was initiated three minutes post mid-bolus (approximately 60seconds into injection) intravenous administration of 400mgI/kg BW of diatrizoatemeglumine/sodium. A second post-contrast scan focused on the bladder and using a smallerdisplayed FOV was then performed. This was followed by a third focused post contrast scanperformed after insertion and inflation of a urinary balloon catheter to determine if this techniquehelped or hindered the interpretation of images.Results: The ureters and UVJ were well visualized in all dogs on the post-contrast scans, andcontrast medium was visualized within the ureter at the UVJ in all dogs on at least one of thefirst 2 post-contrast scans. Jets of urine containing contrast medium could be seen emanatingfrom the trigone on 8/12 ureters on at least one of the 3 scans. The UVJ was clearly seen to bedistinct from the internal urethral orifice in all dogs. Bladder volume affected the distancebetween the left and right UVJ, but not the distance between the UVJ and the urethra. Averagepre- and post-contrast ureteral diameters were 2.03mm (SD = 0.32, range = 1.33-2.72mm), and2.47mm (SD = 0.47, range = 1.51-3.48mm), respectively. Average total scan time was 72minutes. Significant delays during scanning were encountered due to x-ray tube heat load. Theshortest scan time was 55 minutes. Urinary catheterization did not aid in interpretation.Conclusion: In six normal dogs, CTEU was easily performed with minimal patient preparation.At three minutes, the ureters were easily seen using half the dose of contrast medium typicallyused in conventional EU. Multiple (up to 3) scans of the UVJ may be necessary to visualize thecontrast medium within a ureter at the entrance into the bladder, or to visualize the urine jet intothe bladder. Because bladder volume did not affect the distance of the UVJ to the urethra,standardization of volumes may not be necessary. Although scanning time was considerable,studies focused on the bladder trigone and UVJ may be appropriate in clinical patients with UVJdisorders (e.g., ureteral ectopia). This would shorten scanning times due to reduced heat load onthe x-ray tube, and permit more scans of the region of interest.

CLINICAL USEFULNESS OF FLUID ATTENUATED INVERSION RECOVERY-WEIGHTING, T2*-WEIGHTING, AND CHEMICAL FAT SATURATION MRITECHNIQUES AS Tidwell, DVM, JLC Morin, RT (R, MRI) Tufts University School ofVeterinary Medicine, North Grafton, MAPurpose: The purpose of this study was to assess the clinical usefulness and ultimately the roleof fluid attenuated inversion recovery weighting (FLAIR), gradient echo susceptibility- or T2*-weighting, and chemical fat saturation (FAT SAT) in the MRI service at Tufts UniversitySchool of Veterinary Medicine (TUSVM). These techniques are used to supplement spin echo(SE) sequences during MR imaging with the intent of improving the sensitivity and specificityof the procedure. However, they also have inherent limitations, artifacts and pitfalls that mayhamper interpretation and do add to the overall scan time of the procedure. It was felt that astudy to assess their utility was needed to better define their place in routine MR imaging atTUSVM and to help increase the radiologists' awareness of their advantages and disadvantages.Methods: Mobile MRI service was instituted at TUSVM beginning in March 2000 using aSiemens 1.0 Tesla superconducting magnet. Scanning protocols were established during the firstfew months of service with the help of an MRI applications specialist. It was determined that, inaddition to T1- and T2-weighted SE pulse sequences, FLAIR and T2*-weighting would beroutinely performed on all scans of the head, but would be used only as needed for all other bodyareas. FAT SAT was to be employed only as needed for all areas. The following parameters wereused: FLAIR TR= 9000, TE=105, TI=2300; gradient echo T2*-weighting TR=920msec,TE=26msec, flip angle= 20 degrees. Beginning in August 2000, TUSVM radiologists were askedto record the name and case number of patients where interpretation was clearly aided by theuse of FLAIR, T2*-weighting and FAT SAT. The technique was considered to be beneficial ifthe radiologist felt that it 1) helped to formulate a diagnosis or a more specific list of differentialdiagnoses, 2) clarified the significance of a finding, 3) helped to rule out an artifact orpseudolesion, or 4) made the abnormality more conspicuous. Situations where the techniquehampered or confounded interpretation were also documented. All MRI studies were reviewedby the primary investigator and the utilities of each technique recorded.Results: Benefits and pitfalls included: FLAIR: Benefits: improved the conspicuity of lesionscompared to T2-weighted SE images; ruled out pseudolesions created by partial volumeaveraging of CSF in sulci of brain on T2-weighted SE images; differentiated solid from cystic orCSF-filled structures Pitfalls: did not reliably attenuate paranasal and bulla fluid (most likelydue to protein binding in mucinous fluid leading to shortened T1 relaxation and alteration of nullpoint); altered signal intensity of brain cyst on post-Gadolinium images T2*-WEIGHTING:Benefits: ruled out or confirmed presence of hemorrhage within lesions; identified mineralizationin damaged stifle meniscus and menigioma of brain Pitfalls: could not differentiate hemorrhagefrom mineral; low signal/noise of entire image and loss of signal at air-tissue interfaces; was notreliable after Gadolinium was administered (due to susceptibility loss associated withparamagnetic agent) FAT SAT: Benefits: Improved conspicuity and defined extent of enhancedlesions; ruled out pseudolesions caused by fat in bone marrow of skull and type 2 marrowchange of vertebrae; determined fat composition; delineated fat pad/joint fluid margin in stiflePitfalls: Not always reliable if magnetic field was inhomogeneous (eg, nearby IV fluid lines).Conclusion: FLAIR, T2*-weighting, and FAT SAT have an important role in MR imaging ofanimals at TUSVM. Their benefits appear to justify the as-needed usage for extracranialstructures of the head and other body areas and the routine usage of FLAIR and T2*-weightingfor brain imaging provided that they are performed pre-contrast and with pitfalls in mind.

PROLONGED GENERAL ANESTHESIA FOR MAGNETIC RESONANCEOBSERVATIONS OF THE RAT BRAIN

Andrew K.W Wood, MVSc,PhD,* Alan M. Klide,VMD, * Stephen Pickup, PhD, # Harold L.Kundel, MD. # Department of Clinical Studies,* School of Veterinary Medicine, University ofPennsylvania, 3850 Spruce Street, Philadelphia, PA 19104-6010, and the Department ofRadiology,# School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6086.

Purpose:A technique was developed for prolonged general anesthesia in rats during MR observations ofan acute localized brain injury. We needed to consider the narrow bore of the research magnet,the necessity to avoid attaching ferrous components, and the need for an anesthetic machine to belocated outside the room containing the magnet.Methods:General anesthesia was induced and maintained initially with intramuscular agents (ketamine-44mg/kg, xylazine-2.5mg/kg, acepromazine-0.75mg/kg, atropine-0.025mg/kg; 25 rats; 198-530g).As required, additional half doses of the intramuscular agents were given during the placementof a tail vein catheter (26 gauge) and the performance of pre-imaging surgical procedures(bilateral nephrectomy and creation of a localized brain injury). A face mask was constructed byslipping the cone-shaped tip of a disposable rodent restrainer (DecapiCone, Baintree ScientificInc, Baintree, MA) over a rat nose cone (VetEquip Inc, Pleasanton, CA); the hair coat of theneck was clipped and the mask was taped to the skin with surgical tape. At other times anendotracheal tube (14 or 16 gauge; Abbocath-T, Abbott Ireland, Sligo, Republic of Ireland) wasinserted via a tracheotomy. The rat was placed in dorsal recumbency on an acrylic board. Onsome occasions, a water-circulating heating pad (Gaymar T/pump, Gaymar Industries Inc,Orchard Park, NY) was placed between the rat and the floor of the board – it was connected via 8meters of plastic tubing to a pump containing a heater, which maintained the temperature of thepad at about 380 C. On other occasions, an isothermal heating pad was used (DeltaphaseIsothermal Pad, Braintree Scientific Inc, Braintree, MA). The animal was then inserted into atrough, containing a custom built linearly polarized birdcage head coil, and placed in the bore ofa 4.7 T horizontal bore magnet (Varian Unity Inova Console, Palo Alto, CA). The face mask orendotracheal tube was connected to a coxial non-rebreathing inhaled gaseous anesthetic system,and exhaled and excess gases were scavenged. Anesthesia was maintained with oxygen (1.5L/min) and isoflurane (0.5-1.5%). Continuous recordings of oxygen saturation and heart ratewere made using a pulse oximeter (Advantage Medical Electronics Inc, Coral Springs, FL). Theradio-frequency shielding of the birdcage coil was sufficient to eliminate any artifacts carriedinto the magnet by the ferrous wires in the oximeter lead. A fluoroptic thermometer (Luxtron710, Luxtron Corporation, Santa Clare, CA) was inserted through the anus to provide continuousrecordings of rectal temperature. The equipment was located next to the MR imaging controlpanel in an adjacent room. At the completion of the study each rat was euthanized.Results:Duration of intramuscular anesthesia was 75-216 min and subsequent gaseous anesthesia wasadministered for 49-225 min. The technique permitted surgical and experimental procedures,and recordings of vital signs; heating pads were essential for maintaining body temperature.Discussion / Conclusions:The anesthetic method was safe, maintained a stable physiologic state, and could be adapted forrepeated use in the same animal. Supported by NIH RO1-NS-37844.

SONOGRAPHIC OBSERVATIONS OF THE CANINE ELBOW

Van W. Knox, IV, VMD, * Chandra Sehgal, PhD, # Andrew K.W. Wood, MVSc,PhD,*

Department of Clinical Studies,* School of Veterinary Medicine, University of Pennsylvania,3850 Spruce Street, Philadelphia, PA 19104-6010, and the Department of Radiology,# School ofMedicine, University of Pennsylvania, Philadelphia, PA 19104-6086.

Introduction: Clinical diagnostic ultrasound is now widely used in animals and humans as anon-invasive and informative method to investigate anatomy. Sonography is an excellentmodality for studying synovial joints including their soft tissues, bones, and articular cartilage.Sonographic evaluation of the canine elbow joint has received only anecdotal mentioning in theveterinary literature. This project’s purposes are to describe the normal sonographic anatomyand to establish an imaging protocol for the sonographic examination of the canine elbow.

Methods: Sonographic observations were made of each elbow of five dog cadavers (mature,mixed-breeds; three male, two female; 12–17 kg body weight). The linear array sonographicprobe (5-10 MHz, used on an Advanced Technology Laboratories Ultramark 9-HTI, Bothell,WA) had a 3.0 X 1.0 cm footprint. Each thoracic limb was removed, the haircoat was clipped,and sonographic gel was applied. Sonographic images, in standard anatomical planes, weremade of each of the 10 elbows; for each image, the probe’s position was noted. Arthrographywas performed by injecting 2 mL of 120 mg iodine / mL iohexol into the lateral aspect of eachjoint; the sonographic observations were repeated. Images were recorded on single-emulsionfilm as well as a digital camera. In addition, each joint was radiographed [in mediolateral, flexedmediolateral, craniocaudal, caudomedial-craniolateral oblique (Cd75M-CrLO), and craniolateral-caudomedial oblique (Cr15L-CdMO and Cr45L-CdMO) projections]. Lastly, an anatomicdissection was performed of each elbow and sonographic–anatomic correlations wereestablished.

Results: The following bony structures were identified: the lateral and medial humeralepicondyles; the olecranon, anconeal process, and medial coronoid process of the ulna; and thehead of the radius. Synovial fluid within the joint was not identified; however, hyaline cartilage(~ 1 mm in thickness) was seen. The fibers of the lateral collateral ligament (~ 2 mm thick), butnot the medial collateral ligament, were visualized. In addition, the tendons of the tricepsbrachii (~ 6 X 8 mm) and supinator muscles were imaged. Following arthrography, fluid waseasily seen in the elbow articulations, the joint capsule was identified, and the medial coronoidprocess was more clearly demonstrated. The radiographic and gross anatomic observationssupported the sonographic findings.

Discussion / Conclusions: Our observations demonstrated the importance of a small footprint,high frequency, and linear array probe for producing high-resolution images of the structures ofthe canine elbow. Of particular interest was the improved visualization of the medial coronoidprocess following fluid injection into the joint. The value of sonography for demonstrating thenormal structure of the canine elbow was shown. The routine use of an imaging protocol inwhich sonographic images were made in standard anatomic planes ensured that all regions of theelbow were examined. With the knowledge of normal sonographic anatomy, future clinicalstudies may define the extent and nature of any pathological change.

EVALUATION OF THE EXPERIMENTAL HYDRONEPHROSIS TREATED WITHTRANSARTERIAL EMBOLIZATION IN BEAGLE DOGS

Dongwoo Chang, Jinyoung Heo, Kichang Lee, Youngwon Lee*, Mincheol Choi, Junghee Yoon.College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea. *College ofVeterinary Medicine, Chungnam National University, Taejon 305-764, Korea.Introduction/PurposeRenal artery embolization has been used as primary therapy for unilateral hydronephrosis inhuman patients and served as safe, reliable, and minimally invasive alternative to nephrectomy.The purpose of this study was to evaluate the embolic effects of iohexol-ethanol mixture withcolor Doppler ultrasonography, enhanced-computed tomography, magnetic resonance image inbeagle dogs with experimental hydronephrosis.MethodsThree Beagle dogs were randomly assigned to 2 groups 1 and 2 each. Each group wasanesthetized with isoflurane and right ureter was ligated. At day 16, under general anesthesia,femoral artery in two dogs was catheterized, and selective angiography of the renal arteryaffected with hydronephrosis was performed with a Fastracker-18MX infusion catheter (TargetTherapeutics®). Embolization was performed by injection of ethanol-iohexol mixture. Afterembolization, an arteriogram was obtained. One dog served as control and embolization was notperformed. Color Doppler ultrasonography (SSA260CE, Toshiba), enhanced-CT (W2000,Hitachi), MRI (0.5T, MRP 7000AD, Hitachi) were performed before induction ofhydronephrosis, on day 14 and 30, respectively. Pre-contrast transverse CT images were obtainedfollowing an IV bolus injection of iodinated contrast agent (3ml/kg, Iohexol 300). MRI was doneusing a human knee radiofrequency receiver coil. The MR examinations were initiated with pre-scanning in a sagittal plane followed by transverse T1 and T2-weighted images.ResultsHydronephrosis were confirmed by thin renal cortex, dilation of renal pelvis and resistive indexgreater than 0.7 in three beagle dogs at day 14. T2-weighted images and ultrasonography revealedthat dilated renal pelvis was filled with fluids in hydronephrosis and renal artery blood flow wasdetected by enhanced CT and color Doppler ultrasonography. Immediately after embolization,arteriogram showed ablation of arterial flow to the kidney. Enhanced-CT scan and color Dopplerultrasonography at day 30 revealed that arterial blood flow to the kidney was not detected inembolized kidney contrary to hydronephrotic kidney.Discussion/ConclusionResults of this study suggest that complete renal embolization is a viable alternative tonephrectomy in beagle dogs in case of hydronephrosis and embolic effects can be evaluated withenhanced CT and color Doppler ultrasonography.

THE PRELIMINARY REPORT: SUPERPARAMAGNETIC IRON OXIDEENHANCED MAGNETIC RESONANCE IMAGING OF THE LIVER

IN BEAGLE DOGSDongwoo Chang, Bongkyeong Kim*, Youngmin Yun*, Yongmin Hur†, Youngwon Lee‡,Mincheol Choi§, Junghee Yoon§, Jekyung Seong*. *Medical Research Center, †Research Instituteof Radiological Science, Yonsei University College of Medicine, Seoul 120-752, Korea. ‡Collegeof Veterinary Medicine, Chungnam National University, Taejon 305-764, Korea. §College ofVeterinary Medicine, Seoul National University, Seoul 151-742, Korea.Introduction/PurposeThe role of superparamagnetic iron oxide (SPIO) as a tissue-specific contrast agent has beenestablished in the human clinical area, especially in hepatic imaging. SPIO particles exhibit atissue-specific biodistribution to the reticulo-endothelial system, where they predominantlyincrease transverse T2. In this study, as a preliminary experiment for applying contrast MagneticResonance Imaging (MRI) for diagnosis of canine liver disease, MR images were acquired withfast gradient echo technique in beagle dogs before and after injection of SPIO.MethodsFive Beagle dogs with male were anesthetized with intravenous ketamine HCl and pancuronium-bromide and mechanically ventilated on O2 with enflurane. All dogs were imaged in dorsalrecumbency, using a human head radiofrequency receiver coil with a 1.5 T magnetic fieldstrength MRI unit (GE Medical Systems). Image acquisition techniques of dynamic liver imagingwith Fast Gradient Echo Recalled At Steady State (FGRE) were performed before and after SPIOinjection. During MR scanning, mechanical ventilation was stopped for about 20 seconds. Theeffect on signal intensities of ROIs was calculated as Percentage Signal Intensity Loss (PSIL).The signal intensities of liver were measured before and after infusion of SPIO. Routine liver andkidney tests were done at baseline and 1, 24, 48, 72 hours after SPIO infusion.Results66±10% of PSIL was detected at 20 min and it increased until the last point of MR scanning. Theliver intensity of all dogs drops to half its value after 20 min. The effect of motion was minimizedby breath holding technique. SPIO did not have any adverse effects on the dogs on routine liverand kidney function tests.Discussion/ConclusionSPIO-enhanced FGRE provides hepatic signal reduction and can be performed with breathholding. It is recommended in veterinary clinics that post-enhanced imaging for detection anddelineation of primary liver tumor, benign tumor, and hepatic metastases in dogs be acquired atleast 20 min after injection of SPIO with FGRE techniques that involve breath holding.

A COMPARSION OF DIFFERENT TECHNIQUES IN VX2 TUMOR

CELL IMPLANTATION

(1)Yungchang Lin, PhD., (2)Jeonhor Chen, M.D., (2)Yuanhon Jen, M.D., (1)Kunwang Han,

D.V.M.,

(1)College of Veterinary Medicine, Chung-hsing University, Taichung 40227, Taiwan

(2)Department of Radiology, China Medical College Hospital, Taichung 40402, Taiwan

Introduction/Purpose : The liver might harbor primary tumors and is the most common sitefor metastases from gastrointestinal tumors and malignant melanoma. Early detection orexclusion of a neoplasm is important for appropriate treatment. The authors compared fourmethods for tumor implantation into the rabbit liver for experimental purposes.Methods : Fifty-five New-Zealand white rabbits, each weighing about 2.8-3.2kg, were usedfor the experiment. The rabbits were divided into 4 groups. Four different implantationmethods were used to induce VX2 carcinomas respectively. In group one (n=10), tumor cellswere directly injected into rabbit liver. In group two (n=19), we used alcoholic cotton swappressed on the injected site after injection. In group three (n=16), we injected agarose to theneedle track after the tumor cells suspension was implanted to prevent cancer seeding. Ingroup four (n=10), we directly transplanted 1 mm3 of the tumor block into both the left andright lobe of the rabbit liver. The growing of the tumor cells were evaluated by CT scan aftertwo weeks of inoculation.Results: The successful inoculation was defined as no tumor seeding in the needle tract,peritoneum, and subcutaneous area. The successful rate for the four groups (I, II, III, and IV)were 10%, 32%, 88%, and 92% respectively. Agarose injection followed tumor cellssuspension injection has comparable success rate as that of direct tumor blocktransplantation.Discussion/Conclusions_With highly successful implantation rate, direct injection followedby agarose prevention is a convenient technique and is very useful whenmultiple implantation sites are demanded.