Effect of clinicopathologic factors on visibility of colorectal polyps with FDG PET.

摘要

OBJECTIVE: The objective of our study was to clarify which clinicopathologic factors affect the FDG PET visibility of colorectal polyps. MATERIALS AND METHODS: We used statistical methods in a retrospective examination of factors affecting the visibility of 87 colorectal polyps in 50 patients who underwent PET for cancer screening. RESULTS: PET depicted 37% (32/87) of polyps. Univariate analysis revealed significant associations between polyp visibility and polyp size, histologic grade (p < 0.001 each), type (p = 0.004), and patient age (p = 0.049) but not sex or polyp location. The visualization rate increased with increases in polyp size (< or = 5 mm, 12%; 6-10 mm, 47%; > or = 11 mm, 59%) and severity of dysplasia (indefinite or low-grade dysplasia, 13%; high-grade dysplasia, 67%; polyp with early carcinoma, 75%) and was higher for pedunculated polyps (59%) than for nonpedunculated polyps (27%). Multivariate analysis showed that histologic grade was the strongest factor (p < 0.001) among three independent factors (histologic grade, type, and age). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for visualization of high-grade or early carcinoma polyps to be removed were 71%, 87%, 78%, 82%, and 80%. Maximum standardized uptake values did not differ significantly between visualized polyps with indefinite or low-grade dysplasia and visualized polyps with high-grade dysplasia or early carcinoma. CONCLUSION: Histologic grade is the strongest independent factor in FDG PET visibility of colorectal polyps. FDG PET visibility may be helpful for predicting whether a polyp should be removed or observed. FDG PET findings also may suggest the need to alter the treatment of patients with colorectal polyps.