Incidental colonic fluorodeoxyglucose uptake: correlation with colonoscopic and histopathologic findings.
OBJECTIVE
To evaluate the pattern and degree of incidental colonic fluorodeoxyglucose (FDG) uptake in patients without colorectal carcinoma who underwent whole-body FDG positron emission tomography (PET) for other purposes and compare them with colonoscopic and/or histopathologic findings.


METHODS
Cases of 27 patients without known history of colorectal carcinoma who were referred for evaluation with whole-body FDG PET and displayed incidental colonic uptake were reviewed retrospectively. Colonoscopy was performed in 10 patients; histopathologic analysis, in two; and both, in 15. The colonic FDG uptake patterns were nodular-focal, nodular-multifocal, segmental, and diffuse. The FDG uptake level was scored with a four-point scale in relation to hepatic uptake. Binomial distribution was used to calculate 95% CIs for the probability of finding an abnormality at histologic examination, as predicted by findings at FDG PET.


RESULTS
Colonoscopic findings in eight patients with a diffuse uptake pattern were normal. Thirteen patients with nodular high FDG uptake had pathologic findings. Six (22%) of the 27 patients were not suspected of having a malignancy, and seven had benign neoplasms. With a 95% CI, nodular high FDG uptake implies at least a 79% chance that histopathologic findings may be abnormal. Colitis was seen in five of six patients with a segmental pattern of high FDG uptake.


CONCLUSIONS
Colonoscopy is a reasonable next step for further diagnostic examination of patients who display nodular high FDG uptake in the colon. Diffuse FDG uptake often is associated with normal findings at colonoscopy, while segmental high uptake may imply inflammation.
PET Imaging Science Center, Division of Nuclear Medicine, Department of Radiology, Keck School of Medicine, University of Southern California, 2250 Alcazar St, Suite 101, Los Angeles 90033-4609, USA.
Rozet
R
Tatlidil
Hossein
H
Jadvar
James R
JR
Bading
Peter S
PS
Conti
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003092:Colitis / Q000473:pathology; D003106:Colon / Q000378:metabolism* / Q000473:pathology; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D007408:Intestinal Absorption / Q000502:physiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014055:Tomography, Emission-Computed
D019788:Fluorodeoxyglucose F18