Preoperative Evaluation of Patients with Hemifacial Spasm by Three-dimensional Time-of-Flight (3D-TOF) and Three-dimensional Constructive Interference in Steady State (3D-CISS) Sequence.

PURPOSE: The purpose of this study was to investigate and evaluate the accuracy and the preoperative diagnostic value of high-resolution magnetic resonance imaging (MRI) techniques, three-dimensional time-of-flight (3D-TOF) and three-dimensional constructive interference in steady state (3D-CISS) sequence, solely or in combination for the detection of the relationship between the facial nerve and adjacent vessels in patients with hemifacial spasm (HFS). METHODS: A total of 95 patients with primary HFS were subject to 3D-TOF and 3D-CISS MRI. The MR images were then used to evaluate the anatomical neurovascular relationships, and the results were compared with the surgical findings. We categorized the neurovascular relationship into three types: compression, contact, and neighboring or distant. Compression and/or contacts between root exit zone (REZ) and vessels were defined as positive, whereas neighboring or distant was considered to be negative. RESULTS: 3D-TOF combined with 3D-CISS assessment showed that 94 of 95 patients had artery compression or contact at REZ, whereas the remaining patient had compression at the peripheral branch of the facial nerve but not at REZ. The positive rates and the overall accuracy were 98.95 and 100 %, respectively, for the 3D-TOF combined with 3D-CISS assessment; 92.63 and 93.68 %, respectively, for the 3D-TOF assessment; and 85.26 and 86.32 %, respectively, for the 3D-CISS assessment. The positive rates and overall accuracy for the 3D-TOF combined with 3D-CISS assessment was significantly higher than those for the 3D-TOF or 3D-CISS assessment. CONCLUSIONS: Combination of 3D-TOF with 3D-CISS imaging well delineates the relationship between the facial nerve and adjacent vessels in terms of increased positive rates and accuracy.