The segmental distribution and clinical significance of colorectal fluorodeoxyglucose uptake incidentally detected on PET-CT.
BACKGROUND
Unexpected focal colorectal fluorodeoxyglucose (FDG) uptake is becoming a common clinical dilemma with the increasing utilization of positron emission tomography (PET). These findings may subsequently reveal malignant or premalignant pathology.


OBJECTIVE
In addition to reporting the prevalence of clinically significant colonic pathology associated with unexpected focal FDG uptake, this study analysed the correlation between pathological colonic segments with those reported on the FDG-PET scan.


METHODS
The reports of 2071 consecutive PET-computed tomography (PET-CT) scans performed in a calendar year were reviewed. Information regarding subsequent patient investigation and management was collected from medical records. The segments harbouring foci of unexpected bowel FDG uptake were compared against the eventual outcome(s) of the endoscopic and pathological investigations.


RESULTS
Among the 62 individual patients represented, 37 (60%) were investigated further. Clinically unsuspected neoplasms were found in 68% of those investigated, including 10 diagnosed with carcinoma. In addition, an unknown bowel lymphoma and 19 colonic adenomas were discovered. The positive predictive value for pathology was higher in the proximal colon than the distal colon. The segments in which the pathological findings were identified correlated well with those reported as abnormal on PET-CT.


CONCLUSIONS
Unexpected bowel FDG uptake on PET-CT is associated with a high incidence of neoplastic pathology. In particular, focal FDG uptake in the proximal colon is associated with a high positive predictive value for neoplasm. The location of pathology is strongly concordant with endoscopic findings.
Lee
Joseph C
JC
Departments of Nuclear Medicine, Royal Brisbane and Women's Hospital, Queensland, Australia. Joseph_Lee@health.qld.gov.au
Hartnett
Gemma F
GF
Hughes
Brett G M
BG
Ravi Kumar
Aravind S
AS
D000236:Adenoma / Q000000981:diagnostic imaging / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000473:pathology; D003106:Colon / Q000000981:diagnostic imaging / Q000473:pathology*; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D003111:Colonic Polyps / Q000000981:diagnostic imaging / Q000532:radiotherapy; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D014057:Tomography, X-Ray Computed; D055815:Young Adult
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18