THE URINARY TRACTMethods of examinationPlain film of the abdomen – patient in supine position, kidneys,

ureteral and bladder areas. Assessment of the size, shape and position of the kidneys, the presence of calcium, psoas muscle abnormalities.

IVU – i.v. injection of radioopaque contrast medium. Serial films are obtained over 25 minutes as the contrast agent is excreted by the kidneys for visualization of the renal collecting system, ureters and bladder (first film obtained after 1 minute and a second film after 5 minutes). Compression – film. Patient preparation – bowel cleansing to remove gas and fecal matter from the colon.

Contraindications to injection of i.v. contrast medium :- hypersensitivity to the contrast agent- renal and hepatic disease- asthma- a serum creatinine level higher than 1,5 – 1,8 mg/100ml- multiple myeloma- history of severe allergy

US CTMRIRetrograde pyelography – cystoscopy and catheterization of the

ureters are necessary.Antegrade pyelography – a needle is placed percutaneously into the

renal pelvis from a posterolateral approach and either fluoroscopic or ultrasonic guidance is used.

Conventional percutaneous nephrostomy, brush biopsy, stent placement, stone dissolution or extraction, dilation of stenosis can be performed

Renal angiography – first global aortography followed by selective renal artery catheterization. Used for renal angioplasty/stenting and renal embolization.

Cystography – a urethral catheter is inserted and the bladder is filled with contrast medium. Indications: bladder rupture, tumors, diverticula.

Renal scintigraphy – 99Tc. Indication – renal function.

Anomalies in number

Renal agenesis – single kidney. Method of choice – angiography.

Supernumerary kidney –the anomalous kidney is small - the other kidney on the same side is often smaller than the normal kidney on the opposite side.- demonstration of the presence of a separate pelvis, ureter and blood supply is necessary for the diagnosis.

Anomalies in size and form

Hypoplasia

– usually associated with hyperplasia on the other side.-The hypoplastic kidney functions normally.-the collecting system is small -there is a normal relation between the amount of

parenchyma and the size of calices and renal pelvis.

-Differentiai diagnosis - acquired atrophic kidney – small kidney because of vascular or inflammatory disease.

Anomalies in size and form

Hyperplasia – is associated with agenesis or hypoplasia

on the opposite side - more properly termed compensatory hypertrophy. Conditions that usually cause bilateral renal

enlargement: -acute glomerulonephritis, -lymphoma, leukemia in children, -systemic lupus erithematosus,- polycystic disease, -bilateral renal vein thrombosis, -amyloidosis, -sarcoidosis, -lobular glomerulonephritis, -total lipodystrophy.

Fusion anomalies

Horseshoe kidney – the lower poles of the kidney are joined by a band of soft tissue, the isthmus.

-the long axis of the kidney is reversed the lower pole is nearer the midline than the upper.

-associated rotation anomaly the calyces are directed backward or posteromedially.

-the ureters tend to be streched over the isthmus partial obstruction is not unusual dilation of the pelvis and calyces.

Crossed ectopy – fusion of the kidneys on the same side; - the lower kidney is ectopic and its ureter crosses the

midline to enter the bladder normally on the opposite side.

Anomalies in position

Ectopy – pelvis, thorax

Nephroptosis – downward displacement and more mobility of the kidney than usual.

Malrotation – results from incomplete or excessive rotation and urographic study indicates the degree of anomaly.

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Anomalies of the renal pelvis and ureterUreteropelvic junction anomalies

– bilateral but not always simmetrical. Duplication of the pelvis and ureter Retrocaval ureter – is limited to the right side.

- The ureter passes to the left behind the IVC.Ureterocele – intravesical dilation of the ureter immediately proximal to its orifice in the bladder. - resembles a cobra head in shape.

- When the ureterocele is not filled with contrast - radiolucent mass within the opacified bladder in the region of the ureteral orifice.

- If it is filled, the lesion is outlined by a radiolucent wall that stands out in contrast to the filled bladder and to the filled, dilated, distal ureter.Ureteral diverticula

OBSTRUCTIVE UROPATHYNonobstructive hydronephrosis

– diabetes, - infections, - appendicitis, peritonitisCongenital hydronephrosis

– obstruction at the UPJ, - vesicoureteral reflux, - congenital ureterocele,

- urethral valves, congenital strictures.Acquired hydronephrosis

– tumors, - calculi, - strictures, - radiation therapy, - surgery, - prostatic enlargement, - pregnancy in the third trimester.

OBSTRUCTIVE UROPATHY

Imaging findings

-US method of first choice to evaluate patients with suspected hydronephrosis (mild, moderate, severe).

-CT + i.v.contrast medium – useful to assess the cause of obstruction.

-Urography – early : flattening of the normal concavity of the calyx + decrease in the rate of contrast material accumulating in the collecting system. - Calyces then gradually enlarge with progressive destruction of parenchyma. - A prolonged and increasingly dense nephrogram is characteristic of acute renal obstruction. - In severe cases do percutaneous nephrostomy.

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CALCULIIncidence – 5% of population; 20% at autopsy.Recurrence of stone disease – 50%.Predisposing conditions – calyceal diverticuli, renal tubular acidosis, hypercalcemia, hypercalciuria.

The radiographic density of a calculus depends on its calcium contents:- Calcium calculi (opaque) 75% - calcium oxalate and phosphate.- Struvite calculi (opaque) 15% - magnesium ammonium phosphate:”infection stones”; - Cystine calculi (less opaque) – cystinuria.- Nonopaque calculi – uric acid, xanthine, mucoprotein matrix

calculi in poorly functioning, infected urinary tract.

Radiographic featuresCalculus - determine size, number, location Radioopaque calculus are best detected on KUB or helical CTRadiolucent calculi are best detected by IVU

US – renal calculi - hyperechoic focus, posterior shadowing

IVU - Delayed and persistent nephrogram ureteral obstruction - Ureter distal to calculus is narrowed (edema, inflammation), may create false impression of stricture - Ureter proximal to calculus is persistently minimally dilatedCT

- detects most calculi regardless of calcium content- Helical CT is very useful to detect small calculi

Location – 3 narrow sites:UPJ, at crossing of ureter with iliac vessels, UVJComplications:- Forniceal rupture (pyelosinus backflow)- Chronic calculous pyelonephritis- XGPTreatment options:-Small renal calculi ( 2,5cm) – ESWL

(extracorporeal shock wave lithotripsy)- Large renal calculi ( 2,5 cm) – percutaneous removal- Upper ureteral calculi – ESWL- Lower ureteral calculi – ureteroscopyDifferential diagnosis- Gallstones- Calcification of costal cartilage- Calcified mesenteric nodes- Calcifications in cysts and tumors- Vascular calcification

Staghorn calculus

URINARY TRACT INFECTIONAcute pyelonephritisAcute bacterial infection of the kidney and urinary tract – Proteus, Klebsiella, E.ColiTypes - focal type – lobar nephronia - diffuse type – more severe and extensiveRole of imaging studies:- Define underlying pathology – obstruction, reflux, calculus- Rule out complications – abscess, emphisematous pyelonephritisRadiographic featuresUS - renal enlargement (edema) - loss of corticomedullary differentiation (edema)- IVU – delay of contrast excretion, narrowing of collecting system,

striated nephrogram, - CT - areas of decreased perfusion by

Chronic pyelonephritisCriteria for diagnosis: - Scarring - can affect the entire thickness of renal substance the involved papilla is retracted secondary dilation of its calyx-the involved area irregular surface depression -The dilated calyx - smooth margin, variable shape-Renal tissue adjacent to the involved area is normal or hypertrophied -unifocal or multifocal, one or both kidneys-decreased size of the involved kidney

RENAL ABSCESSUsually caused by gram negative bacteria. Underlying disease – calculi, obstruction, diabetes, AIDS. Radiographic featuresWell-delineated focal renal lesionCentral necrosisThickened abscess wall with contrast enhancementPerinephric inflammatory involvement

Complications: retroperitoneal spread of abscess, renocolic fistula

TUBERCULOSISGU tract is the second most common site of TB involvement after the lung. The disease is typically due to hematogeneous spread.Clinical – history of pulmonary TB, pyuria, hematuria, dysuria

Radiographic featuresDistribution – unilateral involvement is more common – 70%Size – early - kidneys are enlarged - late - the kidneys are small, autonephrectomyParenchyma - calcifications – curvilinear, mottled, amorphous

- Papillary necrosis, parenchymal cavity - Tuberculoma - Parenchymal scarring

Collecting system - infundibular stenosis- amputated calyx- Corkscrew ureter – multiple stenosis- “pipestem” ureter - narrow, rigid, aperistaltic segment

CYSTIC DISEASESymple cystsProbably arise from obstructed tubules or ducts.They do not communicate with the collecting system.Clinical – most commonly asymptomatic; rare hematuria Radiographic featuresIVU – lucent defect, cortical bulge, round indentation on the collecting systemUS – anechoic, sharply marginated, smooth walls, very thin septation may be seenCT – homogeneous water density, no enhancement. - smooth cyst wall, sharp demarcation from the surrounding renal parenchyma

Complicated cysts – Bosniak classification:- category 1 lesions – benign simple cyst- category 2 lesions – these minimally complicated cysts are benign but have certain radiologic findings of concern.This category includes septated cysts, minimally calcified cysts, high-density cysts- category 3 lesions – complicated cystic lesions that exibit some radiologic patterns also seen in malignancy. This category includes complex septated cyst, heavily calcified cyst. Surgery is usually performed- category 4 lesions – clearly malignant lesions with large cystic component. Irregular margins, solid vascular elements

ADULT POLYCYSTIC KIDNEY DISEASECystic dilation of collecting tubules as well as nephrons. Autosomal dominant trait.Clinical – slowly progressive renal failure.Treatment – dialysis, transplant.Associated findings – hepatic cysts, intracranial aneurysm, cysts in pancreas and spleen.Radiographic features-kidneys are enlarged and contain innumerable cysts, creating a boselated surface.-They do not communicate with the collecting system- calcification of cyst wall is common- pressure deformities of calyces and infundibula- “swiss-cheese” nephrogram

BENIGN TUMORSAngiomyolipomaHamartomas containing fat, smooth muscle and blood vessels.Treatment – small lesions are not treated; large and symptomatic lesions are resected or embolizedComplication – tumors may spontaneously bleed because of their vascular elementsCT method of choiceAdenomaLow grade adenocarcinoma with no metastatic potential. Usually detected at autopsyOncocitomaThese tumors arise from oncocytes of the proximal tubule.Radiographic features – central stellate scar (CT) , well-defined sharp bordersJuxtaglomerular tumor (reninoma)Secretion of renin causes HTN, hypernatremia, hypokalemia.Tumors appear as small hypovascular masses

RENAL CELL CARCINOMA

Synonyms – renal adenocarcinoma, hypernephroma, clear cell carcinoma

Clinical – hematuria, flank pain, palpable mass, weight loss, paraneoplastic syndrome: hypertension (renin), erythrocytosis (erythropoietin), hypercalcemia (PTH), gynecomastia (gonadotropin), Cushing syndrome (ACTH)

Risk factors – tobacco, phenacetin long term use, Von Hippel-Lindau disease, chronic dialysis, family history

Radiographic featuresIVU – renal mass with renal contour deformity,

- calyceal displacement and destructionUS – hypoechoic, nonhomogeneous, irregular bordersCT – hypodense mass, enhancement - calcifications, necrosis, irregular bordersAngiography – hypervascular, caliber irregularities of tumor vessels,

- prominent AV shunting, venous lakes, - preoperative embolizationStagingStage I – tumor confined to kidneyStage II – extrarenal but confined to Gerota’s fasciaStage III A – venous invasion; B- lymph node metastases ; C – bothStage IV A – direct extension into adjacent organs ;

IV B – metastases (lung, liver, bone, adrenal, contralateral kidney)Therapy – radical nephrectomy, chemotherapy, radiotherapy

Renal pelvis tumors – transitional cell carcinomaTumors are often multifocal – ureter, bladder.

Radiographic features – - irregular filling defect - polypoid mass. - wall thickening – infiltrative cancer

Staging

Stage I – mucosal lamina propria involvedStage II – into but not beyond muscular layerStage III – invasion of adjacent fat / renal parenchymaStage IV - metastases

URINARY BLADDER

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