Display of MR angiograms: maximum intensity projection versus three-dimensional rendering

Objective: The purpose of this study is to clarify the most useful technique of MR imaging in demonstrating the collateral venous pathways due to portal hypertension. Subjects: Twenty-eight cirrhotic patients with collateral venous pathways due to portal hypertension and three patients without them were studied. We evaluated the detectability of collateral vessels of flow-enhanced transverse MR images by time of flight effect, projection MR angiography using the maximum intensity projection technique and three-dimensional (3D) computer graphic images, by using the arterial portography as the standard. Results: Flow-enhanced transverse MR images showed 98% of the collateral vessels detected by angiography, however, the connection of each vessel was obscure. Fully 81% of the collateral vessels were seen by projection MR angiography, and 98% of them by the 3D computer graphic images. Conclusion: The detectability of collateral vessels of 3D computer graphic imaging was better than that of the projection MR angiography and was as accurate as that of transverse MR imaging. 3D Computer graphic images provided complex anatomical information in a more easily understood fashion than either transverse MR images or projection MR angiography.