Aim The present study evaluates the role of PET parameters pertaining to incidentally detected foci of colorectal uptake (IFCU) on FDG PET/CT in the differentiation of benign, premalignant and malignant lesions.

Methods This retrospective study included 74 patients. The colonoscopic and histopathological findings were regarded as the reference standards. The results were evaluated on a lesion basis by dividing the lesions into three groups as benign, premalignant and malignant. The maximum standardized uptake value (SUVmax), SUVmean, metabolic tumor volume(MTV) and total lesion glycolysis(TLG) values of the three groups were compared.

Results There were 88 IFCU in a total of 74 patients (27 female, 47 male, mean age 65 years). Of the 88 IFCU, 26 were qualified as benign, 42 as premalignant and 20 as malignant. Malignant + premalignant lesions were found in 62/88 (70.4 %) of the IFCU. The SUVmax of the benign lesions was significantly lower than those of the premalignant and malignant lesions; and SUVmean was lower than that of the malignant lesions. The MTV of the malignant lesions was significantly higher than that of the premalignant and benign lesions; and TLG was higher than that of the premalignant lesions. The optimum cut-off value in differentiating between the malignant and non-malignant lesions was 9.15 for SUVmax, 5.05 for SUVmean, 4.7 for MTV and 30.25 for TLG.

Conclusion PET parameters can guide the differentiation of benign, premalignant and malignant lesions with IFCU. Besides, patients with IFCU should undergo further evaluation due to high probability of premalignant and malignant lesions.