Effect of scanning in the supine and prone positions on dilation of air-charged colon in CTVC

Objective To evaluate the effect of scanning in the supine and prone positions on dilation of air-charged colon in CT virtual colonoscopy (CTVC). Methods Thirty cases underwent CTVC scanning in both the supine and prone positions immediately before colonoscopy, and the dilation of each intestine was graded. The differences of colon dilation in different positions were compared. Results In supine and prone position, there were 26 (17.3%) and 22 (14.7%) insufficient dilating colon segments, respectively, and only 5 (3.3%) insufficient dilating colon segments in double positions. 15(50.0%)and 13(43.3%)colons dilated insufficiently in supine and prone position, respectively, and decreased to 5 (16.7%) in double positions. The dilation of rectum, sigmoid colon, and transverse colon had significant difference in different positions. Conclusion When performing CTVC, it is highly necessary to scan in both the supine and prone positions in order to ensure the sufficient dilation of colon. In supine position, the dilation of transverse colon is better, while the dilation of rectum and sigmoid colon in prone position is superior to that in supine position.