Clinical Use of PET/CT in Peritoneal Carcinomatosis from Colorectal Cancer

Peritoneal carcinomatosis (PC) from colorectal cancer has been associated with poor survival but new approaches and postoperative chemotherapy have improved survival. The purpose of this study was to evaluate the clinical utility of imaging in cases of PC from colorectal cancer.This is a retrospective single-institution study which examined 23 patients with colorectal cancer who underwent positron emission tomography (PET), computed tomography (CT) and received a final diagnosis PC in our institute between 2005 and 2010.PET/CT detected PC in 19 of 23 cases (82.6%), whereas CT detected PC in 6 of 20 cases (30%). Four cases of PC were FDG-negative, all with maximal size <10mm, representing smaller tumors. FDG-negative PC was diffuse in 3 cases and nodular in 1. The distributed spotty uptake of FDG-negative PC was harder to detect. Diagnostic detection of PC was only achieved in 3 of 23 cases (13%). In the remaining cases, clinical diagnosis was metastasis to lymph nodes, recurrence, or normal FDG uptake by intestine.PET/CT offers efficient detection of PC and has the potential to improve clinical diagnosis when coupled with an understanding of the pathways of flow for ascitic fluid and peritoneal seeding.