Usefulness of 18F-FDG Uptake Value Assay in the Differential Diagnosis of the Colorectal Polyp: Case Report

Of recent 18F-FDG PET/CT is increasingly used not only for the initial diagnosis and staging and restaging of malignant tumors but also for the screening purpose of colorectal polyps and carcinomas.1,2) It is also utilized for clinical and pathological investigations of adenomas3) and villous adenomas4) of the colon yielding encouraging results. PET/CT differential diagnosis of benign from malignant colorectal tumor has mainly been based on two factors, size and 18F-FDG metabolic rate of tumor. Chen et al.2) could detect colonic adenomas exceeding 7 mm in size and distinguish adenoma from carcinoma as FDG uptake value was greater in the latter. Yasuda et al.3) noted that the PET scan positivity rate rose as tumors were 13 mm or more in size. On the other hand, FDG uptake in carcinomas has been shown to vary due to the presence and amount o