Brief Article
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World J Gastroenterol. Jun 14, 2013; 19(22): 3453-3458
Published online Jun 14, 2013. doi: 10.3748/wjg.v19.i22.3453
Incidental focal colorectal 18F-fluorodeoxyglucose uptake on positron emission tomography/computed tomography
Soung Hoon Cho, Sang Woo Kim, Won Chul Kim, Jae Myung Park, Ie Ryung Yoo, Sung Hoon Kim, Seong Taek Oh
Soung Hoon Cho, Sang Woo Kim, Won Chul Kim, Jae Myung Park, Division of Gastroenterology, Department of Internal Medicine, Seoul St. Mary’s Hospital, The Catholic University of Korea, Seoul 137-701, South Korea
Ie Ryung Yoo, Sung Hoon Kim, Department of Radiology, Seoul St. Mary’s Hospital, The Catholic University of Korea, Seoul 137-701, South Korea
Seong Taek Oh, Department of Surgery, Seoul St. Mary’s Hospital, The Catholic University of Korea, Seoul 137-701, South Korea
Author contributions: Cho SH and Kim SW designed and performed the research; Kim WC, Park JM, Ie RY, Oh ST, Kim SH collected and analyzed the data; Cho SH and Kim SW wrote the paper.
Correspondence to: Sang Woo Kim, MD, Professor of Medicine, Division of Gastroenterology, Department of Internal Medicine, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Seocho-gu, Seoul 137-701, South Korea. viper@catholic.ac.kr
Telephone: +82-2-22582083 Fax: +82-2-22582089
Received: December 25, 2012
Revised: March 20, 2013
Accepted: March 28, 2013
Published online: June 14, 2013
Processing time: 171 Days and 3 Hours
Abstract

AIM: To assess the clinical significance of incidental focal colorectal 18F-fluorodeoxyglucose (18F-FDG) uptake on 18F-FDG-positron emission tomography/computed tomography (PET/CT).

METHODS: The records of all the cases which had undergone colonoscopy after PET/CT within a two weeks interval were reviewed. Adenomas were considered advanced when they were villous, ≥ 10 mm in size, or had high-grade dysplasia. Colorectal cancers and advanced adenomas are collectively referred to as advanced colorectal neoplasms. Receiver-operating characteristic curve analysis was used to determine the significant predictive maximum standardized uptake value (SUVmax) cutoff value for advanced colorectal neoplasms and cancer.

RESULTS: Ninety-five colorectal lesions matched the site of incidental focal colorectal 18F-FDG uptake on PET/CT and 146 did not. Colonoscopy showed advanced colorectal neoplasms corresponding to the site of 18F-FDG uptake in 49 of the 95 (51.5%) lesions with incidental uptake. Of the lesions without incidental uptake, only 6 of 146 (4.1%) had advanced colorectal neoplasms on colonoscopy, indicating a statistically significant difference between the two groups (P < 0.001). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of incidental focal 18F-FDG uptake in identifying advanced colorectal neoplasms were 89.1%, 75.3%, 51.6%, 95.9%, and 78.4%, respectively. In detecting only CRC, these values were 89.2%, 69.6%, 34.7%, 97.3%, and 72.6%, respectively. The significant SUVmax cutoff value for advanced colorectal neoplasms (area under the curve 0.755, P < 0.001) was 4.35, with a sensitivity, specificity, PPV, NPV, and accuracy of 75.5%, 65.2%, 69.8%, 71.4% and 70.5%, respectively. For CRC, 5.05 was the significant SUVmax cutoff value (area under the curve 0.817, P < 0.001), with a sensitivity, specificity, PPV, NPV, and accuracy of 84.8%, 71.0%, 80.9%, 89.8%, and 75.8%, respectively.

CONCLUSION: The presence of incidental focal colorectal 18F-FDG uptake on PET/CT with a SUVmax ≥ 4.35 increases the likelihood of an advanced colorectal neoplasm.

Keywords: Positron emission tomography; Adenomas; Computed tomography; Colorectal cancer; Colonoscopy

Core tip: Increased focal uptake of 18F-fluorodeoxyglucose (18F-FDG) in the colon and rectum can be found incidentally during 18F-FDG-positron emission tomography/computed tomography (PET/CT). The presence of incidental focal colorectal 18F-FDG uptake on PET/CT indicated advanced colorectal neoplasms in more than half of the cases. Our study confirms the necessity of colonoscopy when incidental FDG uptake is detected on PET/CT to allow the early diagnosis and management of advanced colorectal neoplasms.