SACRAL PLEXUS - OPTIMAL IMAGING PLANES FOR MR ASSESSMENT

PURPOSE: To identify the optimal imaging planes for magnetic resonance (MR) evaluation of the sacral plexus (SP) and proximal sciatic nerve (SN). MATERIALS AND METHODS: The SPs of 10 healthy adult volunteers we re prospectively studied with T1-weighted MR imaging with custom-built pelvic phased-array coils. The conspicuity of 12 anatomic characteris tics (comprising the SP and their relationship to normal pelvic anatom y) on a series of coronal, axial, and oblique images was graded. Resul ts were evaluated with the Kruskal-Wallis and Wilcoxon signed rank tes ts. RESULTS: At least two planes were necessary to assess the anatomy of the SP and SN. Analysis of average conspicuity scores showed that t he direct coronal and direct axial planes were the best overall and we re superior to other imaging planes in the demonstration of the L-4 an d L-5 ventral rami, the lumbosacral trunk, the S-1 contribution to the SN, and the SN in the greater sciatic foramen. The sacral coronal pla ne was best for the visualization of the bony sacrum, sacral foramina, and proximal S-1 to S-4 nerve roots. The remaining imaging planes had limited utility. CONCLUSION: MR imaging with a combination of direct coronal and direct axial planes enables thorough evaluation of all com ponents of the SP and proximal SN.