Raysum reconstruction algorithm in MR cholangiopancreatography.

Magnetic resonance cholangiopancreatography (MRCP) is a new, non-invasive imaging technique for the visualization of the biliary ducts. The presence of stones within the choledocus is easily detectable in source images. However, three-dimensional reconstructions using the maximum intensity pixel (or projection) algorithm (MIP) fail to reproduce accurately the eventual presence of filling defects or parietal irregularities due to biliary stones. We used the Raysum algorithm in addition to the MIP in evaluating MRCPs of twelve patients with known choledocolithiasis. A visualization of the stones was obtained in nine (75%) patients by using the Raysum while visualization was obtained in one patient by using MIP. No additional sequences are required, and the post-processing time takes only a few seconds. The Raysum reconstruction can be successfully associated to the MIP in the three-dimensional evaluation of biliary stones in MRCP.