title: Detection of flat colorectal polyps at screening CT colonography in comparison with conventional polypoid lesions.
abstract: BACKGROUND
  Although the screening of small, flat polyps is clinically important, the role of CT colonography (CTC) screening in their detection has not been thoroughly investigated.
  
  
  OBJECTIVE
  To evaluate the detection capability and usefulness of CTC in the screening of flat and polypoid lesions by comparing CTC with optic colonoscopy findings as the gold standard.
  
  
  METHODS
  We evaluated the CTC detection capability for flat colorectal polyps with a flat surface and a height not exceeding 3 mm (n = 42) by comparing to conventional polypoid lesions (n = 418) according to the polyp diameter. Four types of reconstruction images including multiplanar reconstruction, volume rendering, virtual gross pathology, and virtual endoscopic images were used for visual analysis. We compared the abilities of the four reconstructions for polyp visualization.
  
  
  RESULTS
  Detection sensitivity for flat polyps was 31.3%, 44.4%, and 87.5% for lesions measuring 2-3 mm, 4-5 mm, and ≥6 mm, respectively; the corresponding sensitivity for polypoid lesions was 47.6%, 79.0%, and 91.7%. The overall sensitivity for flat lesions (47.6%) was significantly lower than polypoid lesions (64.1%). Virtual endoscopic imaging showed best visualization among the four reconstructions. Colon cancers were detected in eight patients by optic colonoscopy, and CTC detected colon cancers in all eight patients.
  
  
  CONCLUSIONS
  CTC using 64-row multidetector CT is useful for colon cancer screening to detect colorectal polyps while the detection of small, flat lesions is still challenging.
authors: Diagnostic Imaging Center, Saiseikai Kumamoto Hospital, Kumamoto University, Kumamoto, Japan.
authors: Takashi
authors: T
authors: Sakamoto
authors: Katsuhiko
authors: K
authors: Mitsuzaki
authors: Daisuke
authors: D
authors: Utsunomiya
authors: Katsuhiko
authors: K
authors: Matsuda
authors: Sadahiro
authors: S
authors: Yamamura
authors: Joji
authors: J
authors: Urata
authors: Megumi
authors: M
authors: Kawakami
authors: Yasuyuki
authors: Y
authors: Yamashita
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D002400:Cathartics / Q000008:administration & dosage; D016009:Chi-Square Distribution; D003111:Colonic Polyps / Q000000981:diagnostic imaging* / Q000473:pathology; D023881:Colonography, Computed Tomographic / Q000379:methods*; D003113:Colonoscopy; D003287:Contrast Media / Q000008:administration & dosage; D003974:Diatrizoate Meglumine / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011092:Polyethylene Glycols / Q000008:administration & dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D002400:Cathartics; D003287:Contrast Media; D011092:Polyethylene Glycols; D003974:Diatrizoate Meglumine