Delineation of small nerves and blood vessels with three-dimensional fast spin-echo MR imaging: comparison of presurgical and surgical findings in patients with hemifacial spasm.

BACKGROUND AND PURPOSE We applied a 3D fast spin-echo (3D-FSE) MR imaging technique to the preoperative and postoperative evaluation of patients with hemifacial spasm. METHODS The study group comprised 20 patients. All images were acquired on a 1.5-T MR system with a 3D-FSE sequence. RESULTS In all 20 patients, the courses of the seventh and eighth cranial nerves were depicted separately, and the arteries presumed to be responsible for the hemifacial spasm were seen to be in contact with the facial nerves at the root exit zone (REZ). Eight patients underwent neurovascular decompression. In all patients, the presumed responsible blood vessels depicted by 3D-FSE MR imaging corresponded to intraoperative findings. In addition, postoperative 3D-FSE images confirmed the separation of the facial nerve from a contiguous vessel at the REZ. DISCUSSION The 3D-FSE technique makes it possible to obtain extremely high-quality images of microstructures in the cerebellopontine cistern, and it has several advantages over conventional angiography: it is noninvasive and able to depict the cranial nerves and surrounding vessels in the same image without contrast material, and it may be useful for postoperative evaluation of the decompression procedure. This imaging technique is expected to prove useful for the clinical evaluation of hemifacial spasm.