Ascending colon rotation following patient positional change during CT colonography: a potential pitfall in interpretation.
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.
Kim
Ji Yeon
JY
Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Songpa-gu, Seoul, South Korea.
Park
Seong Ho
SH
Lee
Seung Soo
SS
Kim
Ah Young
AY
Ha
Hyun Kwon
HK
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