title: Ascending colon rotation following patient positional change during CT colonography: a potential pitfall in interpretation.
abstract: OBJECTIVE
  To investigate the degree and pattern of ascending colonic rotation as patients moved from supine to prone positions during CTC.
  
  
  METHODS
  A search of our CTC and colonoscopy database found 37 patients (43 eligible lesions) who fulfilled the following criteria: colonoscopy-proven sessile polyps ≥ 6 mm in the straight mid-ascending colon, lesion visualisation in both supine and prone CTC, and optimal colonic distension. A coordinate system was developed to designate the polyp radial location (°) along the luminal circumference, unaffected by rotation of the torso. The degree/direction of polyp radial location change (i.e. ascending colonic rotation) between supine and prone positions correlated with anthropometric measurements.
  
  
  RESULTS
  Movement from supine to prone positions resulted in a change in the radial polyp location of between -23° and 79° (median, 21°), demonstrating external rotation of the ascending colon in almost all cases (2° to 79° in 36/37 patients and 42/43 lesions). The degree/direction of rotation mildly correlated with the degree of abdominal compression in the anterior-posterior direction in prone position (r = 0.427 [P = 0.004] and r = 0.404 [P = 0.007]).
  
  
  CONCLUSIONS
  The ascending colon was usually found to rotate externally as patients moved from supine to prone positions, partly dependent on the degree of abdominal compression.
authors: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Songpa-gu, Seoul, South Korea.
authors: Ji Yeon
authors: JY
authors: Kim
authors: Seong Ho
authors: SH
authors: Park
authors: Seung Soo
authors: SS
authors: Lee
authors: Ah Young
authors: AY
authors: Kim
authors: Hyun Kwon
authors: HK
authors: Ha
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D003106:Colon / Q000000981:diagnostic imaging*; D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture; D015203:Reproducibility of Results; D012399:Rotation; D012680:Sensitivity and Specificity