Nuclear Medicine in Gastroenterology

Nuclear Medicine techniques provide this functional information that can be vital in early diagnosis and can help in appropriate management

GASTROINTESTINAL IMAGING

Liver-spleen scintigraphy : 99mTc-sulfur colloid

GI bleeding : 99mTc-RBC

Ectopic gastric mucosal scan : 99mTcO4-

Normal liver scan

Multiple SOL in liver

FNH

Tc-99m RBC scan: Hemangioma

Meckel’s scan

CHOLESCINTIGRAPHY

biliary obstruction, D.D. of biliary atresia and neonatal hepatitis, bile leakage

Normal : liver (5 mins), intrahepatic biles ducts (10-15 mins), common bile, gall bladder and duodenum duct (15-30 mins), small intestine (>30 mins)

Hepatobiliary physiology: Tc-99m Mebrofenin studyNormal scan Biliary atresia

24h7h2h 4h

1h30m15m5m

MECKEL SCAN

PET Assembly

GASTROINTESTINAL MALIGNANCIESColorectal

Hepatobiliary

Pancreatic

Esophageal and Gastric

Small Bowel: Adenoca, Sarcomas/GIST, Carcinoids, Lymphomas etc.

CT PET

Lesion

‘….PET imaging is typically used to measure metabolic activity which is increased in tumors. PET-CT system have a number of advantages over CT or PET imaging alone that may allow more accurate assessment of tumor response by distinguishing scar tissue from residual tumor and by facilitating easier orthogonal measurements in three planes. Therefore, modification of RECIST guidelines to incorporate this new technology may have added benefit..’

Macheda ML et.al. Molecular and cellular regulation of glucose transporter (GLUT) proteins in cancer. J Cell Physiol 2005; 202: 654-662.

Normal PET Scan

Transverse

Coronal Sagittal MIP

Colorectal Malignancies: Initial evaluation

•Diagnosis based on Colonoscopy

•Preoperative staging: Intraoperatively

•Preoperative staging with FDG PET•Good sensitivity for detection of primaries (FP: IBD)•Poor performance for regional LN involvement•Better sensitivity and specificity than CT for hepatic mets detection

Kantarova I et.al. J Nuc Med 2003; 44: 1784-1788

Mukai et.al. Oncology Reports 2000; 7: 85-87

Abdel-Nabi et.al. Radiology 1998; 206: 755-760.

65 yr old pt presenting for initial staging of colon ca

Incidental FDG uptake in GI tract on PET/CT

Agress H et.al. Radiology 2004; 230(2): 417-422

Kamel EM et.al. J Nucl Med 2004; 45: 1804-1810

Gutman F et.al. Am J Roentgenol 2005; 185: 495-500

No. of WB PET

Incidental focal FDG uptake

Unexpected proven tumors (histopath cnfrmd)

N=1750 3.3% 21/42 pts

N=3281 3% 69/98 pts

N=1716 2.6% 13/20 advance neoplasms

Colorectal Carcinoma: Detection of recurrence

•70% are resected with curative intent (1/3rd have recurrence within 2 years

•25% have recurrence to one site and are potentially curable by surgery

•Conventional methods for rec. detectn•CEA: Elevated in only~2/3rd of pts; no localizatn•CT: Suboptimal for peritoneal and mesenteric LN mets and for differentiation of post tr changes from recurrence•Barium enema: local recurrence (accuracy 80%)

•For rec. Sensitivity~90% & Specificity>70%

Colorectal Ca: FDG PET for rec. detection

•Meta-analysis: 11 studies (n=577 pts)•Sensitivity: 97%•Specificity: 75% (higher for local recurrence and hepatic mets>95%)•Change of management: 29%

•Summary of literature for recurrence evaluation: •Sensitivity: PET 94% CT 79% (2244 pt studies)•Specificity: PET 87% CT 73% (2244 pt studies)•Change in management: 32% (915 pt studies)

Huener RH et.al. J Nucl Med 2000; 41: 1177-1189

Gambhir SS et.al. J Nucl Med 2001; 42 (suppl): 9S-12S

s10

Ca colon, rising CEA with anastomotic recurrence confirmed on endoscopy

FDG PET, CT and MRI for detection of colorectal hepatic mets: A meta-analysis•Meta-analysis comparing non-invasive methods: 61/165 data sets included

Bipat S et.al. Radiology 2005; 237: 123-131

Patient Lesion Lesion>1 cm

CT-non helical

60% 52% 74%

CT-helical 65% 64% 74%

MR no Gad 76% 66% 65%

MR Gad 69%

MR SPIO 90%

PET 95% 76%

Ca Colon pre treatment: Surgically resectable hepatic mets (black arrow) in addition to primary (blue arrow)

FDG PET for detection of extrahepatic mets

•Study of over 155 pts analyzed by site of lesions•Sensitivity: FDG PET>CT for all locations except lungs where they are equivalent

(FDG PET particularly helpful for abdomen, pelvis and retroperitoneum)•Specificity: FDG PET>CT at all sites, except the retroperitoneum

Valk PE et.al. Arch Surg 1999; 134: 503-511

Diffuse Omental metastasis from Ca colon

Metastatic colon Ca: Known liver mets, unsuspected bone mets

Ca rectum pretreatment evaluation: Unsuspected femoral metastasis

37 yr F; h/o metastatic colonic ca to liver s/p colectomy and hepatic resection presenting for restaging

FDG PET for detection of mets in pts with rising CEA levels and normal work up including CT

•Compiled data from four studies show that FDG PET demonstrated tumor in 84% (142/169 pts) and allowed surgical resection in 26% pts.

Flanagan FL et.al. Ann Surg 1998; 227: 319-323

Valk PE et.al. Arch Surg 1999; 134: 503-511

Maldonando A et.al. Clin Pos Imaging 2000; 3: 170

Flamen P et.al. Eur J Cancer 2001; 37: 862-869

Clinical impact of FDG PET in Colorectal Cancer

Clinical impact of FDG PET in patients with Colorectal Carcinoma: Survival data•Survival at 3 years of patients with FDG PET: 77% (higher than historical series)

•Survival at 5 years of hepatic mets preop. staged with:

•CIM (19 studies with 6,019): 30%•FDG PET (100 patients): 58%

•Contribution: Detection of occult disease and reduction of futile surgeries

Strasberg SM et.al. Ann Surg 2001; 233: 320

Fernandez FG et.al. Ann Surg 2004; 240 (3): 438-447

Monitoring response to chemoembolization

H/o RFA stable disease on CT; active on PET

Conclusion: FDG PET in Colorectal Carcinoma•Diagnosis: Incidental focal uptake in GI

tract:~30-50% are malignant

•Detection of recurrence:•Presurg tumor N & M staging: unsuspected mets, extrahepatic mets (PET>CT)•Rising CEA levels in absence of known source•Equivocal lesions: post surgical sites, liver etc.•Change in management in ~30% of pts

•Detections of hepatic mets:•Sensitivity of PET-CT>MR>ceCT

Esophageal Cancer•Prospective study of 74 pts comparing FDG PET, CT and EUS:

FDG PET CT+EUS

CT EUS

Primary Sens: 95%

Locoregn LN

Sens: 33% sp: 89%

Sens: 81% sp: 67%

Stage IV Sens: 74%Sp: 90%

Sens: 47Sp: 78%

Sens: 41Sp: 83%

Sens: 42Sp: 94%

•Flamen P et.al. J Clin Oncol 2000; 18: 3202-3210

Esophageal cancer: Effectiveness of strategies•Comparison of 6 strategies:

•CT alone•CT+EUS with FNA•CT+thoracoscopy and laparoscopy (TL)•CT+EUS with FNA+TL•CT+PET+EUS with FNA: most effective

•PET+EUS+FNA: most effective

•Wallace et.al. Ann Thorac Surg 2002; 74: 1026-1032

80 yr old man referred for initial staging of ca eso

Suspected case of ca esophagus (wall thickening on CT) Unsuspected right hip bone mets

Carcinoma of Pancreas: Pre-treatment staging

Metastasis in Liver

Transverse Coronal Sagittal MIP

FDG PET in Hepatocellular Carcinomas

FDG PET in Cholangioca and GB ca

FDG PET in Cholangioca and GB ca

63 yr male with h/o surgery for GB cancer 3 yrs earlier; Diagnosis: Recurrent GB

carcinoma

Carcinoma of Duodenum: Pre-treatment staging

Transverse Coronal Sagittal MIP

•Account for 0.1 to 0.3% of all GIT tumors. 70% benign and malignant in 30% cases.

•Typically multiple tumors, tend to be located predominantly in small intestine, arise from muscularis propria and have an exophytic growth pattern

•Express c-kit (CD-117) a tyrosine kinase growth factor receptor

GIST

•Imatinib Mesylate a tyrosine kinase inhibitor is used in treatment of non-resectable GIST lesions

•In patients with recurrent GIST FDG PET has a similar sensitivity and specificity (86% and 98%respectively) as CT scan

•However FDG PET predicts response to therapy earlier than CT in up to 22.5% of patients. This is because change in size of tumor is not a reliable indicator of tumor response.

•Accurate tumor response can be predicted in about 85% of patients after 1 month of therapy and in 100% patients between 3 to 6 months.

GIST

GIST showing response to Imatinib in 6 weeks

GIST showing response to Imatinib

24 hr post tr 3 weeksBaseline scan

Simple technique of water ingestion can clear a suspected hypermetabolic focus proving it to be non-malignant

Referring Surgeons’ Questions:

Is there a viable disease in the pelvis in this treated case of abdominal NHL?

Repeat spot view post laxative

Initial view

•FALSE NEGATIVES•Small volume disease (<1 cm) or necrotic lesions with only thin rim of viable tissue•Mucinous carcinomas (Sensitivity 58% vs. 92% for non-mucinous lesions)

LIMITATIONS

•FALSE POSITIVES•Trauma, infection, granulomatous disease•Uptake at site of previous anastomosis•Post RT (Do PET after 2 to 3 months of RT)

•A paradigm shift from “size” criterion to “biology” of tumor is required to make an effective use of this modality in patient management.

CONCLUSIONS

•FDG PET can play a very important role in Staging, Treatment monitoring and evaluation of recurrences in GI malignancies.

•However it is not a “magic wand”. Like any other diagnostic modality it has its own limitations in the evaluation of GI malignancies (uptake in the inflammatory lesions, low uptake in mucinous tumors & in the lesions < 1 cm and normal tracer uptake in the gut that may interfere in lesion evaluation)

•Nevertheless with a judicious use of PET in appropriate clinical scenario we can hope for a better patient care.

CONCLUSIONS

Hence it is imperative to use the diagnostic procedures judiciously…. Along with appropriate clinical judgment to alleviate the patient’s anxiety and help in patient’s management

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