1. Nuclear Medicine in Gastroenterology

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

4. GASTROINTESTINAL
IMAGING
Liver-spleen scintigraphy : 99mTc-
sulfur colloid
GI bleeding : 99mTc-RBC
Ectopic gastric mucosal scan :
99mTcO4-

5. Normal liver scan Multiple SOL in liver

6. FNH

7. Tc-99m RBC scan: Hemangioma

8. Meckel’s scan

9. 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)

10. Hepatobiliary physiology: Tc-99m Mebrofenin study
Normal scan Biliary atresia

12. 24h7h2h 4h
1h30m15m5m

13. MECKEL SCAN

14. PET Assembly

15. GASTROINTESTINAL
MALIGNANCIES
Colorectal
Hepatobiliary
Pancreatic
Esophageal and Gastric
Small Bowel: Adenoca, Sarcomas/GIST, Carcinoids,
Lymphomas etc.

16. CT PET
Lesion

17. ‘….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..’

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

19. Normal PET Scan
Transverse
Coronal Sagittal MIP

20. 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.

21. 65 yr old pt presenting for initial staging of colon ca

23. 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

24. 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%)

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

26. 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

27. s10

28. Ca colon, rising CEA with anastomotic recurrence confirmed
on endoscopy

29. 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%

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

31. 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

32. Diffuse Omental metastasis from Ca colon

33. Metastatic colon Ca: Known liver mets,
unsuspected bone mets

34. Ca rectum pretreatment evaluation:
Unsuspected femoral metastasis

35. 37 yr F; h/o metastatic colonic ca to liver s/p colectomy
and hepatic resection presenting for restaging

36. 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

37. Clinical impact of FDG PET in Colorectal Cancer

38. 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

39. Monitoring response to chemoembolization

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

42. 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

43. 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: 47
Sp: 78%
Sens: 41
Sp: 83%
Sens: 42
Sp: 94%
•Flamen P et.al. J Clin Oncol 2000; 18: 3202-3210

44. 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

45. 80 yr old man referred for initial staging of ca eso

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

47. Carcinoma of Pancreas: Pre-treatment staging
Metastasis in
Liver
Transverse Coronal Sagittal MIP

49. FDG PET in Hepatocellular Carcinomas

50. FDG PET in Cholangioca and GB ca

51. FDG PET in Cholangioca and GB ca
63 yr male with h/o surgery for GB cancer 3 yrs
earlier; Diagnosis: Recurrent GB carcinoma

52. Carcinoma of Duodenum: Pre-treatment staging
Transverse Coronal Sagittal MIP

53. •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

54. •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

55. GIST showing response to Imatinib in 6 weeks

56. GIST showing response to Imatinib
24 hr post tr 3 weeksBaseline scan

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

58. 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

59. •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)

60. •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.

61. •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

63. 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

64. THANK YOU