Clin Endosc.  2012 Jun;45(2):145-150. 10.5946/ce.2012.45.2.145.

The Clinical Meaning of Benign Colon Uptake in 18F-FDG PET: Comparison with Colonoscopic Findings

• Roh SH
• Jung SA
• Kim SE
• Kim HI
• Lee MJ
• Tae CH
• Choi JY
• Shim KN
• Jung HK
• Kim TH
• Yoo K
• Moon IH
• Kim BS

• KMID: 2048852
• DOI: http://doi.org/10.5946/ce.2012.45.2.145

Abstract

BACKGROUND/AIMS
Benign colon 18F-fluorodeoxyglucose (FDG) uptake is frequently observed in asymptomatic individuals. Aims of this study were to investigate the benign colon uptake by whole body FDG-positron emission tomography (PET) in asymptomatic adults and to correlate those results with colonoscopic and histologic findings.
METHODS
Among 3,540 subjects who had undergone FDG-PET, 43 subjects who were diagnosed to have benign colon uptake in FDG-PET and underwent colonoscopy were retrospectively reviewed. Subjects were classified as diffuse or focal groups based on their FDG uptake patterns. PET results were analyzed together with colonoscopic and histologic findings.
RESULTS
Forty-three subjects showed benign colon uptake in FDG-PET; 28 of them were shown as the diffuse group, while other 15 subjects were classified as the focal group. Five subjects among those showed diffuse uptake were diagnosed as adenoma. Seven among 15 subjects who showed focal uptake were diagnosed as adenocarcinoma (n=2), adenoma (n=3), or non-neoplastic polyp (n=2). Positive predictive values were 25% in the diffuse group and 47% in the focal group.
CONCLUSIONS
We recommend that patients showing benign FDG uptake in the colon should be further evaluated by colonoscopy, especially for patients with focal FDG uptake.

Keyword

18F-fluorodeoxyglucose positron emission tomography; Benign colon uptake; Colonoscopy

MeSH Terms

Adenocarcinoma
Adenoma
Adult
Colon
Colonoscopy
Fluorodeoxyglucose F18
Humans
Polyps
Retrospective Studies
Fluorodeoxyglucose F18

Figure

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  Fig. 1 Classification according to benign colon uptake pattern in fluorodeoxyglucose positron emission tomography. (A) Diffuse group. It showed diffuse colon uptake. (B) Focal group. It showed focal colon uptake.

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  Fig. 2 Per-lesion standardized uptake value intensity (maximum standardized uptake value [SUVmax]) mean and standard deviation for different colonoscopic findings. The neoplastic lesion had significantly increased maximal SUV value (p=0.009) and high grade dysplasia had greater maximal SUV value among adenomas (p=0.02). The SUVmax is 6.1±3.2 for low grade dysplasia adenoma (n=10), 12.9±4.2 for high grade dysplasia adenoma (n=2), 9.6±3.4 for well to moderately differentiated adenocarcinoma (n=44) and 6.6±2.0 for poorly differentiated adenocarcinoma (n=4).

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  Fig. 3 A 62-year-old male with prostate cancer. (A) Intense focal standardized uptake (maximum standardized uptake value, 4.2) is located in descending colon. (B) A 13-mm polyp is found in colonoscopy. (C) The pathologic diagnosis is villotubular adenoma with focal adenocarcinoma involving mucosa (left, H&E stain, ×40; right, ×200).

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  Fig. 4 A 70-year-old male with nasopharyngeal cancer. (A) Intense focal standardized uptake (maximum standardized uptake value, 10.1) is located in transverse colon. (B) A 15-mm polyp is found in colonoscopy. (C) The pathologic diagnosis is focal well differentiated adenocarcinoma with coexisting villotubular adenoma (left, H&E stain, ×40; right, ×200).

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