Positron emission tomography/computed - PowerPoint Presentation

1. Positron emission tomography/computed tomography with 18F-fluorocholine improve tumor staging and treatment allocation in patients with hepatocellular carcinomaJournal of Hepatology, March 2018Chalaye, J., Costentin, C.E., Luciani, A., Amaddeo, G., Ganne-Carrié, N., Baranes, L., Allaire, M., Calderaro, J., Azoulay, D., Nahon, P., Seror, O., Mallat, A., Soussan, M., Duvoux, C., Itti, E., Nault, J.C.,Journal Club, 11/06/2018

2. Barcelona Clinical Liver Cancer (BCLC) classificationLiver CT scan Liver MRI scan

3. The role of PET/CT in HCC diagnosisPET/CT using 18F-FDG:18F-fluorodeoxyglucose (18F-FDG) is a marker of glycolysis in cells18F-FDG PET/CT has been proposed to detect poorly differentiated HCC, but is limited by its inability to detect well-differentiated HCCPET/CT using 18F-FCH:18F-fluorocholine (18F-FCH) is a precursor of phospholipid synthesiscould be a useful marker of well-differentiated HCC, nor for the poorly onesDual-tracer PET/CT using both 18F-FDG and 18F-FCH

4. Materials and methods177 patients with active HCC on conventional imaging or a history of HCC and suspicion of new HCC, who had been investigated with dual-tracer PET/CT (18F-FDG PET/CT and 18F-FCH PET/CT) between 2012 and 2015, were retrospectively identified in the nuclear medicine database of two French academic centers (APHP Henri Mondor Hospital, Creteil and APHP Jean Verdier Hospital, Bondy). Conventional imaging consisted of liver MRI alone + pulmonary CT in 42 patients, liver CT + pulmonary CT in 77 patients and liver MRI + liver CT + pulmonary CT in 73 patients.

5. The different clinical situations for which dual-tracer PET/CT were performed were: active HCC staging before treatment (122, 64%) unexplained rise in serum AFP (9, 4%)a doubtful lesion on conventional imaging (25, 13%)assessment before liver transplantation in patients with a history of HCC, but without active HCC (36, 19%)

6. New lesions identified by PET/CT were confirmed as HCC during follow-up (ended in April 2017, median time of follow-up 35 months) based on the following:histological analysis of the lesionacquisition of typical radiological features of HCC (wash-in and wash-out on either MRI or CT) for intrahepatic lesions progression at imaging, defined by an increase in size of over 100% at one year for extrahepatic lesions

7. 1) Active HCC staging before treatment (122,64%)In 122 patients with a conventional imaging of HCC lesion, staging based on conventional imaging alone using the BCLC classification was the following:18F-FDG PET/CT alone and 18F-FCH PET/CT alone identified new lesions in 20 (16%) and 21 patients (17%) respectively, whereas dual-tracer PET/CT identified new lesions in 26 (21%) patients.

8. Among 26 new lesions identified by dual-PET/CT, 24 (92%) were confirmed as HCC based on histological findings (n = 7, 27%) or follow-up imaging (n = 18, 63%). One hypermetabolic lesion corresponded to breast cancer and one patient was lost to follow-up.

9. BCLC staging was upgraded in 12 cases (10%) and 10 cases (8%), with 18F-FDG PET/CT alone and 18F-FCH PET/CT alone respectively, and in 14 cases (11%) with dual-tracer PET/CTConsidering dual-tracer PET/CT findings, treatment strategy was modified in 17 cases (14%).

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11. 2) Unexplained rise in serum AFP (9, 4%)In the setting of an unexplained rise in serum AFP, new lesions were identified with dual-tracer PET/CT in four out of the nine cases (44%), one positive with 18F-FDG PET/CT alone, one positive with 18F-FCH PET/CT alone and two positive with both tracers.Among the four patients with new lesions identified by PET/CT, two had new intrahepatic lesions, one had new extrahepatic lesions, and one had both new intrahepatic and extrahepatic lesions, all confirmed based on histology findings or progression seen on imaging during follow-up.

12. 3) Doubtful lesion on conventional imaging (25, 13%) Among the 25 patients with doubtful lesions (either intra- or extrahepatic) on conventional imaging, positive lesions were observed in four cases (16%) with 18F-FDG PET/CT alone vs 10 cases (40%) with 18F-FCH PET/CT alone and in 11 cases (44%) with dual-tracer imaging. In 10 cases (40%), dual-tracer PET/CT results led to treatment modification.Among the 14 patients with doubtful lesions negative on dual-tracer PET/CT, one of the lesions was finally diagnosed as HCC, whereas 11 lesions were not HCC at the end of follow-up and 2 patients were lost to follow-up.

13. 4) Assessment before liver transplantation in patients with a history of HCC, but without active HCC (36, 19%)Among the 36 patients investigated before listing for transplantation, without active HCC on conventional imaging after complete tumor response following bridging therapy, dual-tracer PET/CT identified new lesions in 3 patients (8%): two patients had bone lesions (imaging progression confirming malignancy during follow-up), thereby excluding them from the transplantation program, and one patient had intrahepatic HCC, leading to a new round of chemoembolization before liver transplantation (confirmed as active HCC on explant).

14. The results show that dual-tracer PET/CT (18F-FDG PET/CT and 18F-FCH) is able to identify HCC lesions not detected by conventional imaging, whilst improving the BCLC classification and subsequent management of HCC. Half of the new lesions detected by dual-tracer PET/CT were extrahepatic metastases, mainly in bone, whereas the remaining lesions were either new intrahepatic nodules or macrovascular invasion.Two clinical situations are associated with high numbers of new lesions identified by PET/CT and treatment modification: an unexplained rise in serum AFP and doubtful lesions on conventional imaging. However, the authors acknowledge that the limited number of cases in both groups might have caused overestimation of the added value of PET/CT in these specific situations.

15. None of the patients classified as BCLC 0 had additional lesions identified by PET/CT, suggesting that PET/CT in BCLC 0 is useless in this setting, although robust conclusions are difficult to reach because of the limited number of patients in this subgroup (n = 8, 7%).

16. The main limitation of the studyThe retrospective design The high costs of the of the dual-tracer PET/CTFalse-positive lesions leading to additional testing are potentially associated with anxiety and discomfort for the patient and additional cost for the institution. Thus, the cost-effectiveness of adding dual-tracer PET/CT to HCC pretreatment evaluation should be evaluated. A well-designed prospective study would be useful to properly address these questions.

17. Grazie per l’attenzione