ROLE OF PET CT IN HEPATIC TUMORS in recent days.pptx

PET CT

1. ROLE OF PET CT IN HEPATIC TUMORS MODERATORS DR.MARY. H. BHUYAN DR.P.BORAH DR.D.J.BORPATROGOHAIN DR.L.NATH DR.C.H.THOUMOUNG DR.P.N.TAYE DR.S.S.BISWAS

2. INTRODUCTION PET- Positron Emission tomography Radionuclide used-emits positron- 18 FDG

3. 18 FDG Mc radionuclide used Radioactive form of glucose Half life- 110 min

4. WHY 18-FDG?

5. APPLICATIONS Most important: cancer imaging Primary diagnosis Staging/ detect metastases Response to treatment Recurrence detection

6. ANNIHILATION REACTION

7. COINCIDENCE IMAGING

8. IMAGING PROTOCOL Injected iv-supine position Dose- 0.2 mCi /kg of FDG Uptake period- about 45 min Relaxed-to minimize glu metabolic activity in striated muscle Not to speak-minimize pharyngeal muscle n vocal cord activity Voiding prior to scan-minimize radioactivity accumulation in UB

9. SUV STANDARDIZED UPTAKE VALUE  . For quantification of uptake The concentration of F 18  activity reflects glucose metabolism which is increased in tumor cells and inflammation SUV >4 -- high uptake n points towards malignancy

10. NORMAL UPTAKE B rain, myocardium, liver and spleen , gastrointestinal and urinary tracts

11. CHALLENGES IN INTERPRETING PET AND PET/CT STUDIES

12. Technical pitfalls PET/CT misregistration . Anatomic malalignment of the PET and CT datasets 2. Truncation artifacts

13. Physiologic pitfalls The liver is the major producer of nondietary glucose. Normal liver parenchyma shows a certain degree of FDG uptake, having a mildly intense, uniformly mottled appearance. It can be difficult to distinguish between increased uptake related to a focal lesion and background physiological activity.

14. Other factors FDG uptake related to inflammation or infection O ccasional malignant lesions with low avidity for FDG Altered biodistribution of FDG related to hyperglycemia or hyperinsulinemia M otion artifacts. 

15. BENIGN HEPATIC TUMORS AND TUMOR-LIKE LESIONS

16. The majority of benign tumors and non-tumorous lesions show no FDG uptake, or uptake similar to that of background liver . However, benign tumors and inflammatory and infectious lesions can show false-positive uptake . In the case of equivocal CT and MRI findings, low or no FDG uptake can assist in differentiating benign tumor from malignancy The degree of uptake can differ even among histologically identical tumors, depending on tumor differentiation

17. Hepatocellular adenoma Hepatocellular adenoma (HCA) - benign liver neoplasm that occurs predominantly in women of reproductive age

18. Hepatic cavernous hemangioma and sclerosed hemangioma Cavernous hemangioma is the most common benign hepatic tumor Hemangiomas show similar uptake of FDG to background liver 

19. Focal nodular hyperplasia Focal nodular hyperplasia (FNH) is the second most common benign hepatic tumor and is believed to be the result of a hyperplastic response of hepatocytes to the presence of a preexisting vascular malformation. FDG-PET/CT has uncertain value in the imaging diagnosis of FNH, which commonly exhibits a similar (or even lower) FDG uptake and retention pattern compared with normal liver tissue as they share the same metabolic mechanism. It is of note that FNH is a hypervascular lesion that does not have accelerated glucose metabolism.

20. Angiomyolipoma Angiomyolipoma (AML)/primary hepatic perivascular epithelioid cell tumor is a benign mesenchymal tumor composed of blood vessels, smooth muscle cells, and a varying amount of fat FDG accumulation in AML is similar to that in the normal part of the liver , although the mechanism has not been elucidated. 

21. Inflammation and infection FDG uptake in nonmalignant inflammatory conditions can produce false-positive results, particularly in patients with known or suspected malignancy, and correlation with the CT and MRI findings is important to avoid misdiagnosis.

22. MALIGNANT HEPATIC TUMORS

23. T he majority of primary and secondary malignant tumors show high FDG uptake . However, several tumors can potentially show false-negative uptake; even between tumors that are identical histologically, the degree of FDG uptake can differ according to tumor differentiation or proliferation rate . In certain tumors, the degree of FDG uptake can be used to predict prognosis or therapeutic response

24. HEPATOCELLULAR CARCINOMA FDG accumulation – significantly higher in poorly differentiated HCC than in well and moderately differentiated HCC –thus predictor of grade of HCC differentiation. High FDG-predictor of recurrence and poor survival after liver transplantation n poor response to radiation n transarterial chemoembolization .

25. INTRAHEPATIC CHOLANGIOCARCINOMA

26. Sensitivity of FDG depends on both location and morphology of the lesion. FDG uptake is prominent in nodular or mass forming cholangioca located in the periphery Perihilar type-lower uptake than peripheral type

27. COMBINED HEPATOCELLULAR CHOLANGIOCARCINOMA Primary liver ca with unequivocal presence of both hepatocytic and cholangiocytic differentiation within same tumor. Areas of hepatocytic component show various degree of FDG uptake and areas of cholangiocytic component show high FDG uptake.

28. MALIGNANT LYMPHOMA Malignant lymphoma, divided broadly into Hodgkin’s and non-Hodgkin’s lymphoma The most common of the highly aggressive non-Hodgkin’s lymphomas is diffuse large B-cell lymphoma Secondary hepatic involvement by lymphoma is not uncommon, especially in patients with non-Hodgkin’s lymphoma; whereas primary hepatic lymphoma is extremely rare

29. The degree of FDG uptake correlates with the level of aggressiveness. In general, high FDG uptake is seen in aggressive lymphoma, whereas indolent lymphoma is associated with lower FDG uptake Furthermore, there is strong evidence that increased FDG avidity correlates with poor prognosis and poor response to treatment. The presence of high FDG uptake in a patient with known low-grade lymphoma indicates high-grade transformation

30. Hepatic metastasis The liver is involved more often with metastatic disease than primary liver tumors Most hepatic metastasis show high uptake of FDG

31. Low cellularity due to mucin, cystic component, degeneration, and intratumoral hemorrhage: In cystic tumors, and in those with mucin, degeneration, or cystic change within the tumor, there are fewer viable cancer cells, which can yield low FDG uptake due to their low cellularity

32. PET CT IN FOLLOW UP CASES

33. CONCLUSION FDG-PET/CT imaging has proved invaluable in diagnosis, detection, assessment of differentiation, staging, response to treatment, and prediction of prognosis in a wide variety of hepatic lesions. Knowledge of the degree of FDG uptake in each lesion type is essential for accurate image interpretation and to enable selection of an appropriate therapeutic strategy. An understanding of the underlying molecular background is also valuable in this regard.

34. THANK YOU