Abstract: Objective To explore the value of combined application of magnetic resonance imaging(MRI) 3D-TOF-MRA and 3D-FIESTA-C sequence in the diagnosis of the neurovascular relationship in primary hemifacial spasm(pHFS). 
Methods The MRI data of 58 patients with pHFS who underwent microvascular decompression were retrospectively analyzed. All patients underwent 3D-TOF-MRA and 3D-FIESTA-C sequence scanning, and multiplanar reconstruction was performed on the brainstem, facial nerve and peripheral blood vessels.The adjacent relationship between facial nerve and blood vessel in patients with hemifacial spasm(HFS) was determined.The contact relationship between nerve root and peripheral blood vessels on symptomatic side and non-symptomatic side, as well as the number of nerve compression and deformation was calculated. The responsible blood vessel and its source were further identified, and compared with the intraoperative anatomical results. 
Results In all patients with HFS, compared with the postoperative results of microvascular decompression, the combined application of MRI 3D-TOF-MRA and 3D-FIESTA-C sequence showed that the positive rate of neurovascular contact and compression on the symptomatic side was 94.83%(55/58), and the positive rate of neurovascular contact and compression on the non-symptomatic side was 17.24%(10/58); the difference between the two groups was statistically significant(χ2=373.812, P＜0.05). Anterior inferior cerebellar artery compression was the most common, accounting for 63.79%(37/58), followed by compression of posterior inferior cerebellar artery, vertebral artery, basilar artery, vein and the combined compression of vertebral artery + anterior inferior artery.Of them, 58 patients underwent 59 times of microvascular decompression, of which 2 cases were evaluated as no compression of the facial nerve before operation and during operation, and 1 case as no facial nerve compression before operation but posterior inferior cerebellar artery compression during operation. The sensitivity and specificity of combined application of preoperative MRI 3D-TOF-MRA and 3D-FIESTA-C sequence in the diagnosis of  responsible vascular compression of the facial nerve were 98.2% and 100% respectively. 
Conclusion The combined application of MRI 3D-TOF-MRA and 3D-FIESTA-C sequence in patients with primary facial spasm can accurately determine the adjacent relationship of cranial nerves and blood vessels, and can guide the selection of appropriate treatment plans in clinical practice.

Key words: facial nerve diseases, microvascular decompression surgery, 3D-TOF-MRA, magnetic resonance angiography