Virtual colonoscopy with multi-slice computed tomography

Subject: Using multi-slice computed tomography (MSCT) large body areas can scanned with high spatial resolution. In this study, MSCT was employed for virtual colonoscopy in various pathologies of the colon. Materials and methods: For MSCT a Somatom Plus 4,Volume Zoom scanner, (Siem ens, Forchheim) was employed, equipped with four parallel detector rows. Tw enty-five patients were included in this trial, prior to colonoscopy or par tial colon resection. After cleaning the colon, distension was achieved by insufflation of room air using a rectal tube:The parameters of acquisition and reconstruction were as follows: collimation 4x1 mm and 4x2.5 mm respect ively; tube charge per slice: 140-160 mAs; pitch 5-6; IV contrast medium:12 0 mi Ultravist 300 (Schering) with a flow rate of 3 ml/s; delay: 35 s. For 3D reconstruction we used edge-enhanced volume rendering,virtual colonoscop y and extraluminal views of volume-rendered images. Results: Nine polyps and four of five colon carcinomas were detected using MSCT virtual colonoscopy. In three patients with ulcerative colitis virtual coloscopy revealed morphological alterations compatible with this disease. In two of four patients with multiple diverticula of the colon the true ex tent of the disorder could be assessed in virtual colonoscopy. Conclusion: Utilizing virtual MSCT colonoscopy polyps and cancer of the col on can be reliably detected, if proper cleaning and distension is provided. On axial images alone smaller polyps may be assessed. The high z-axis reso lution of MSCT offers superior conditions for CT-based virtual colonoscopy.