gms | German Medical Science

Objective: Due to the increasing availability of 3.0 Tesla (T) MR devices, neurovascular compression (NVC) syndromes with a pathological vessel-nerve contact are more frequently investigated. An improved representation of the involved fine structures has been reported. The methods of modern image processing make it possible to generate comprehensible, freely projectable anatomical representations that can also be used intraoperatively. Systematic investigations of 3D visualizations from 3.0 T MR data on these diseases are not yet available.

Methods: A consecutive series of 25 patients were prospectively examined with MR and treated with microvascular decompression (MVD) (n=19 trigeminal neuralgia, n=1 glossopharyngeal neuralgia, and n=5 hemifacial spasm). In all patients, data were measured using the CISS (constructive interference in steady state) and the TOF (time of flight) protocol at 1.5 and 3.0 T. In a first step, the CISS data of 1.5 and 3.0 T were processed with segmentation and then presented with techniques of 3D visualization. In the second step, CISS and TOF data of 1.5 and 3.0 T were fused prior the segmentation and again displayed with 3D visualization. For both, 1.5 and 3.0T data, the resulting 3D representations were quantitatively and qualitatively evaluated.

Results: Fundamentally, in 3D visualization the contours of fine structures (nerves, vessels, brain stem surface) are sharper at 3.0 T than at 1.5 T. In the 3D visualization with CISS data only, there were more missing vascular sections at 3.0 T and the overall results were better at 1.5 T. Subsequent manual optimization of the segmentation only led to an improvement at 1.5 T - missing structures at 3.0 T could be uncovered in this way. After fusion of CISS and TOF data, the 3D visualization is improved so that i.a. at 3.0 T missing vessel sections are supplemented. Both field strengths produce anatomically comparable results. The subsequent manual optimization of the segmented fusion data leads to a significant advantage in 3.0 T, as it can effectively eliminate the remaining artifacts and take advantage of sharp contours.

Conclusion: 3D visualization is a powerful tool for planning MVD in NVC syndromes. In principle, 1.5 T data can be used without restrictions. However, using fused CISS and TOF data, 3.0T provides further enhances 3D visualization with improved delineation of anatomical structures, especially cranial nerves and vessels.