68Ga-FAPI-46 PET/MR Detects Recurrent Cholangiocarcinoma and Intraductal Papillary Mucinous Neoplasm in a Patient Showing Increasing CEA with Negative 18F-FDG PET/CT and Conventional CT / 대한핵의학회잡지

A patient with intrahepatic cholangiocarcinoma who underwent hepatic resection with completed neoadjuvant chemotherapy presented with increased CEA levels. Previous whole abdominal and chest CT scan revealed no evidence of local recurrence or metastasis. 68Ga-FAPI-46 PET showed significantly higher tumor-to-background contrast of recurrent tumor and nodal metastasis, which were undetectable in the FDG PET or conventional CT scan. These findings changed patient management. Larger studies with histopathological correlation and comparisons with other imaging modalities are required to validate the diagnostic performance. Moreover, a cystic lesion with FAPI uptake at the neck to the proximal body of the pancreas without FDG uptake is also incidentally noted. Differential diagnoses include sided branch IPMN and serous cystadenoma.

[11]C- Choline and FDG PET/CT imaging of primary cholangiocarcinoma - a comparative analysis

Objective[s]: this study aimed to compare the diagnostic values of 11C-choline and 18F-fluorodeoxyglucose [18F-FDG] positron emission tomography/computed tomography [PET/CT] in patients with cholangiocarcinoma [CCA]

Methods: this prospective study was conducted on 10 patients [6 males and 4 females], aged 42-69 years, suspected of having CCA based on CT or magnetic resonance imaging [MRI] Results. 11C-choline and 18F-FDG PET/CT studies were performed in all patients over 1 week. PET/CT results were visually analyzed by 2 independent nuclear medicine physicians and quantitatively by calculating the tumor-to-background ratio [T/B]

Results: no 11C-choline PET/CT uptake was observed in primary extrahepatic or intrahepatic CCA cases. Intense 18F-FDG avidity was detected in the tumors of 8 patients [%80]. Two patients, who were 18F-FDG negative, had primary extrahepatic CCA. Ki-67 measurements were positive in all patients [range; 14.2%-39.9%]. The average T/B values of 11C-choline and 18F-FDG were 0.4 +/- 0.2 and 2.0 +/- 1.0 in all cases of primary CCA, respectively; these values were significantly lower for 11C-choline [P<0.005]. Both FDG and 11C-choline PET/CT detected metastatic CCA foci in all 8 patients [two patients had no metastases]

Conclusion: as the results suggested, primary CCA lesions showed a poor avidity for 11C-choline, whereas 18F-FDG PET/CT was of value for the detection of most primary CCA cases. In contrast to primary lesions, metastatic CCA lesions showed 11C-choline avidity