title: Effect of clinicopathologic factors on visibility of colorectal polyps with FDG PET.
abstract: OBJECTIVE
  The objective of our study was to clarify which clinicopathologic factors affect the FDG PET visibility of colorectal polyps.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Radiology, Atsuchi Memorial Clinic PET Center, 12-1 Terukuni, Kagoshima City, 892-0841, Japan. toyo.nakajo@dolphin.ocn.ne.jp
authors.forename: Masatoyo
authors.initials: M
authors.lastname: Nakajo
authors.forename: Seishi
authors.initials: S
authors.lastname: Jinnouchi
authors.forename: Yukie
authors.initials: Y
authors.lastname: Tashiro
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shirahama
authors.forename: Eiichi
authors.initials: E
authors.lastname: Sato
authors.forename: Chihaya
authors.initials: C
authors.lastname: Koriyama
authors.forename: Masayuki
authors.initials: M
authors.lastname: Nakajo
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D003111:Colonic Polyps / Q000000981:diagnostic imaging* / Q000473:pathology; D055088:Early Detection of Cancer; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D018709:Statistics, Nonparametric
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18