Figure 16a. Advantage of performing both supine and prone imaging. (a, b) Prone (a) and supine (b) axial CT images show a small filling defect (arrow) in the descending colon. The filling defect is not mobile. (c) Endoluminal CT image shows that the lesion is polypoid (arrow). At colonoscopy, a 5-mm hyperplastic polyp was found.