A Comparison of Positron Emission Tomography and Colonoscopy for the Detection of Advanced Colorectal Neoplasms in Subjects Undergoing a Health Check-Up

Abstract

Background & AimsThere is no agreement as to whether F-18 fluorodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT) screening for advanced colorectal neoplasms is meaningful. This retrospective study was undertaken to determine whether FDG PET/CT may be a valuable screening tool for the detection of advanced colorectal neoplasms.MethodsA retrospective review of the records of 1,109 FDG PET/CT scans acquired from January 2007 to December 2011 was performed. Colonoscopy and FDG PET/CT imaging were performed within two days of each other. The results of colonoscopy were taken as the gold standard, either with or without the results of the histopathological examination. An advanced neoplasm was defined as the presence of a malignant tumor, an adenoma ≥1 cm, or histological evidence of high-grade dysplasia or significant villous components.ResultsA total of 36 subjects had advanced colorectal neoplasms detected by colonoscopy (totaling 38 neoplasms). Six of the 38 neoplasms were also detected by FDG PET/CT. The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of FDG PET/CT in the detection of advanced colorectal neoplasms were 15.8% (6/38), 99.1% (1063/1073), 37.5% (6/16), 97.1% (1063/1095), and 96.2% (1069/1111) respectively. The presence of lesions with an endoscopic size ≤1.5 cm (P<0.001) and low-grade dysplasia (P<0.001) were the main predictors of false-negative FDG PET/CT findings.ConclusionsWe conclude that FDG PET/CT screening of advanced colorectal neoplasms is unwarranted, especially in the presence of lesions with an endoscopic size ≤1.5 cm or low-grade dysplasia.

Sensitivity of 2-[18F]fluoro-2-deoxyglucose positron emission tomography for advanced colorectal neoplasms: a large-scale analysis of 7505 asymptomatic screening individuals

“…On the other hand, the sensitivity per person (16.4 %; 95 % CI 12.1-21.5 %) was very low, as low as the value calculated per colonic site (16.9 %; 95 % CI 12.7-21.8 %). The sensitivity of FDG-PET for advanced neoplasms in this study was almost as low as that found in the Taiwanese study (15.8 %) [21]. On the other hand, the sensitivity in this study was lower than the sensitivity for adenomas of 10 mm or larger found in other previous studies, which ranged between 33 and 100 % [15,16,18,20,22].…”

“…This observation indicates that more attention needs to be paid to the possible existence of colorectal tumors with the aforementioned features even if FDG-PET reveals negative results. In addition to the tumor size and histological grade, which were previously identified as features related to FDG-PET sensitivity in the Taiwanese study [21], the macroscopic type, location, and invasion depth (CRC) were newly identified in this study as features that are associated with FDG-PET sensitivity in a screening population. Considering that the macroscopic type and location were reported to be associated with FDG-PET visibility in some other previous studies [17,20], it is postulated that the present study newly proves the significant association between these features and the detectability of FDG-PET in the screening setting.…”

“…FDG-PET is a noninvasive functional imaging modality that reflects the change in glucose metabolism in tumor cells, and has been applied in oncology [12]. With regard to colorectal tumors, previous studies have shown that FDG-PET can detect not only CRC but also colorectal adenomas, and the sensitivity of FDG-PET for colorectal tumors has been examined in several studies [13][14][15][16][17][18][19][20][21][22][23][24]. However, most members of the study population were not asymptomatic screening individuals.…”

“…Furthermore, for evaluation of the sensitivity of FDG-PET, it is best to analyze those patients who underwent both FDG-PET and colonoscopy simultaneously, which allows the most accurate calculations based on the findings of colonoscopy as the reference. To the best of our knowledge, there have been only two studies evaluating the sensitivity of FDG-PET using asymptomatic screening individuals with the above-mentioned method: a study from Taiwan and one from Korea that examined 1109 and 614 asymptomatic screening individuals respectively [21,24]. In addition to early CRCs, advanced colorectal neoplasms are considered as important target lesions of screening with regard to the efficacy of incidence reduction after screening.…”

“…In addition to early CRCs, advanced colorectal neoplasms are considered as important target lesions of screening with regard to the efficacy of incidence reduction after screening. Of the two previous studies, only the Taiwanese study examined the sensitivity of FDG-PET for advanced colorectal neoplasms, reporting a sensitivity of 15.8 % [21]. However, the study included only 38 advanced neoplasms, and thus it was not considered to be a large enough study to evaluate the sensitivity of FDG-PET for advanced neoplasms.…”