Benign Colonic 18F-FDG Uptake on Whole-Body FDG-PET Scan

cc This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 18 F-fluoro-2-deoxy-D-glucose (FDG) is a functional imaging modality and has been widely accepted in the diagnosis and staging of various malignancies, such as lymphomas, gastrointestinal (especially, colon cancer), and pulmonary cancer. It can measure the amount of accumulation of FDG in cells with high rates of glycolysis. 3 Most cancer cells show high rate of glycolysis and these tumors are well diagnosed by FDG-PET/ CT. There is a report of increased glucose metabolism in colorectal cancer (CRC). 6 Accordingly, FDG-PET has been carried out, even for healthy checkups , and several cases of high colonic FDG uptake revealed colonic premalignancy or malignancy. CRC is the third most common cancer and the major cause of cancer-related mortality in Western countries. 10 Recently, the incidence of CRC is increasing in Korea. Most of CRC develop from adenomatous polyps. Early detection and resection of premalignant polyp can prevent progressive malignant disease. Colonoscopy is regarded as the gold standard for the detection of colonic lesions such as ade-nomatous or malignant polyp. However, colonoscopy is uncomfortable and invasive procedure as a screening modality for CRC. Several studies have suggested a potential role for FDG-PET in the detection of premalignant and malignant le-sions of the colon. 6,11 However, increased FDG uptake is present in benign, inflammatory, or granulomatous processes and in sites of normal, physiologic tracer distribution besides in malignant lesions. 12 Physiologic uptake within gastrointesti-nal tract (GIT) varies in intensity and patterns. These benign type FDG uptake may be falsely attributed to a cancerous eti-ology, and increased tracer activity in malignant lesions may be erroneously interpreted as unrelated to cancer. Large intestine is a well-known site of physiologic uptake and this may interrupt the detection of adenoma or carcinoma of colon. 13 Clinical significance of incidental tracer uptake of colon and needs of further evaluation of these lesion is unclear. In that point, study of Roh et al. 14 has a clinical significance. They investigated the clinical significance of benign colon uptake on a whole-body FDG-PET in asymptomatic adults by correlating them with colonoscopic and histologic findings. This study included only benign appearing FDG uptake cases and this is different from previous studies. They categorized FDG uptakes …