Cholangiocarcinomas are not simple to image because they are located in an area of multiple other organs and there is often associated inflammation and anatomic variation. There are also only a few studies of PET for cholangiocarcinomas and conclusions vary. In a study by Kim et al, FDG PET was not found to be specific enough in detecting hilar cholangiocarcinomas, an observation ascribed to small tumor size or to fibrous or mucinous components of the lesion . Most peripheral cholangiocarcinomas show ring-shaped FDG uptake due to excessive desmoplastic response within the tumor and neovascularity at the periphery. However, these findings are not specific to cholangiocarcinomas, since any lesion with central necrosis can mimic this pattern. Fritscher-Ravens et al found FDG PET more useful in detecting metastases to lymph nodes, the liver, and other distant sites. However, they could not differentiate malignant from benign lesions, since false-positive FDG uptake was seen in granulomatous inflammatory lesions and there were false-negative results in non-FDG-avid mucinous cholangiocarcinomas. NCCN on pp GAL-2-4 only lists CT scans and MRI. The 2012 Bristish update of 2012 does not mention PET. The 2014 guidelines byBridgewater et al says: “Prior to surgical resection,PETscanning may be con-
sidered to help rule out an occult primary as well as to rule out otherwise occult metastatic disease.“.
A recent consensus statement concluded: “PET-CT is recommended in the preoperative staging of intrahepatic and extrahepatic CCA.” In regard to restaging, PET is not well established and NCCN does not list PET in its guidelines
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NCCN, Cholangiocarcinoma, 2019