DETECTION OF MASS LESIONS WITH MR COLONOGRAPHY - PRELIMINARY-REPORT

PURPOSE: To evaluate the performance of magnetic resonance (MR) colono graphy in the detection of colorectal mass lesions. MATERIALS AND METH ODS: Twenty-three patients underwent MR colonography preceding colonsc opy. The colon was filled with a gadolinium-water mixture (1:100) with MR imaging guidance, and the patient was imaged prone and supine with a breath-hold three-dimensional spoiled gradient-recalled sequence. I n addition, two-dimensional spoiled gradient-recalled images were acqu ired before and after intravenous administration of gadopentetate dime glumine. Images were interactively analyzed on the basis of multiplana r reconstruction by two radiologists. For regions that were not conclu sively assessable with multiplanar reconstruction, virtual intralumina l endoscopic images of the colon were reconstructed. MR findings were correlated with colonoscopic results. RESULTS: Two patients were exclu ded from the analysis; Findings in eight of 11 patients were correctly assessed as normal and in six of 10 as mass-positive. In the four pat ients with false-negative findings, one had two 8-mm polyps and the ot her three had polyps smaller than 5 mm. All nine-mass lesions larger t han 10 mm, as well as four of the 10 polyps ranging between 5 and 10 m m, were detected, but all polyps smaller than 5 mm were missed. In con trast to the polyps less than 5 mm, the four missed polyps (5-10 mm) c ould be identified retrospectively on virtual intraluminal endoscopic images. Contrast enhancement was documented in 13 polyps. CONCLUSION: Three-dimensional MR colonography provided virtual colonscopic viewing and helped detection of colonic polyps.