Trigeminal neuralgia: Diagnosis using 3-D magnetic resonancemulti-fusion imaging

Most instances of idiopathic trigeminal neuralgia (TN) are caused by neurovascular contact (NVC) between the offending vessels and the affected trigeminal nerve. Pre-treatment analysis of the MR imaging findings on the severity of the NVC may predict the outcomes of microvascular decompression (MVD) surgery or radiosurgical treatment. In order to visualize the spatial relationships of the NVC, we have developed a method for three-dimensional (3-D) magnetic resonance (MR) multi-fusion imaging, reconstructed with a perspective volume-rendering algorithm, by compositing co-registered data sets of 3-D MR cisternograms, 3-D MR angiograms (noncontrasted and contrast-enhanced), and 3-D computed tomographic (CT) angiograms in a single 3-D image. Technical aspects of the fusion imaging were documented with some comments regarding the MR sequences to characterize the NVC. Severity analysis of the NVC revealed that the NVC in the affected trigeminal nerve was observed more frequently and much more severely than that at the contra-lateral and normal nerves in controls. Pre-operative MVD surgical simulation and inner-view observation from inside the nerve were depicted for the virtual reality. Moreover, comparative fusion images were reconstructed by superimposing the post-MVD images over pre-MVD simulation, which may confirm the success of the nerve decompression by surgical treatment. Consequently, the 3-D MR multi-fusion imaging may be useful for adjunctive diagnosis, planning of the best treatment strategy, and post-treatment follow-up in patients with TN.