Assessment of offending vessels of the idiopathic trigeminal neuralgia for microvascular decompression with 3D MR cisternogram/angiogram fusion imaging

We applied 3D MR cisternogram/angiogram fusion imaging to 9 cases of the idiopathic trigeminal neuralgia for the preoperative assessment of the offending vessels for microvascular decompression (MVD). Fusion images of the 3D MR cisternogram/angiogram were reconstructed by a perspective volume-rendering algorithm from the volumetric data set of MR cisternography (black blood image), obtained by a T2-weighted 3D fast spin-echo sequence, and composed with the co-registered MR angiography (bright blood image), obtained by a 3D time-of-flight sequence with and without contrast medium. The complex anatomical relationship of the offending vessels, including superior cerebellar artery, anterior inferior cerebellar artery, posterior inferior cerebellar artery, vertebral artery and superior petrosal vein, to the root entry zone of the trigeminal nerve was preoperatively assessed on the fusion images from various viewpoints in the cerebellopontine angle cistern and through the simulated surgical approach. The 3D visualization of the nerve-vessel relationship with fusion images was comparative to the intraoperative findings. Fusion imaging of 3D MR cisternogram/angiogram may prove useful in preoperative assessment of MVD for the idiopathic trigeminal neuralgia.