Assessment of incidental focal colorectal uptake by analysis of fluorine-18 fluorodeoxyglucose positron emission tomography parameters

Figure 1 A case with malignant incidental focal ascending colon fluorine-18 fluorodeoxyglucose uptake. A: Focal uptake (black arrow) in the right abdomen on the maximum intensity projection (MIP) image of a 67-year-old man diagnosed with intrahepatic cholangiocarcinoma; B and C: Axial images of fused positron emission tomography/computed tomography (B, white arrow) and positron emission tomography only (C, black arrow) indicating focal uptake of the MIP image (maximum standardized uptake value 9.0); D: Visualization of the lesion by colonoscopy. The lesion was histopathologically diagnosed as an adenocarcinoma of the ascending colon.

Figure 2 Cases with premalignant and benign incidental focal colorectal fluorine-18 fluorodeoxyglucose uptake. A: Focal uptake (black arrow) in the lower abdomen on the maximum intensity projection (MIP) image of a 41-year-old woman diagnosed with stomach cancer; B: Axial view showing a hypermetabolic rectal lesion (white arrow, SUVmax 10.1) diagnosed as rectal villous adenoma; C: Focal uptake (black arrow) in the right lower abdomen on the MIP image of a 42-year-old man diagnosed with stomach cancer; D: Axial view showing hypermetabolism (white arrow, maximum standardized uptake value 8.6) with a final colonoscopy report of “No remarkable mucosal lesion”.

Figure 3 Receiver operating characteristic curves. Receiver operating characteristic (ROC) curves of the maximum standardized uptake value (SUV) and mean SUV of metabolic tumor volume 3.5 of malignant/premalignant lesions. The values of area under the curve are 0.770 and 0.763 and the cut-offs are 7.6 [confidence interval (CI) 0.668-0.0.872, sensitivity 0.686, specificity 0.688] and 4.9 (CI 0.658-0.867, sensitivity 0.667, specificity 0.656), respectively.