A comparison of magnetic resonance angiography and constructive interference in steady state-three-dimensional Fourier transformation magnetic resonance imaging in patients with hemifacial spasm.

Although the decision to perform a microvascular decompression of the facial nerve is based on clinical history and assessment, preoperative imaging of the neurovascular relationships at the REZ is important to exclude a non-vascular cause or identify dolichoectatic vessels that might influence the surgical approach. We designed the current study to compare the specificity and sensitivity of gadolinium-enhanced 3D fast inflow with steady state precession (FISP) MRA with CISS. The imaging findings of 47 patients that had microvascular decompression for hemifacial spasm were retrospectively reviewed in a single blind fashion. The 47 non-symptomatic sides served as controls. Neurovascular contact could be seen in 13/47 (27.6%) in routine T2 axial scans, in 22/35 (62.8%) in high resolution T2W, in 18/34 (52.9%) in the case of MRA, and in all cases (13) when the CISS sequence was used. This study demonstrated 56.2% sensitivity and 50% specificity for MRA with gadolinium enhancement, whereas the CISS sequence can achieve a sensitivity of 100% in correctly demonstrating neurovascular compression in HFS. Overall accuracy of the two methods was 55.8 and 100% for MRA and CISS, respectively. The CISS sequence is superior in identifying neurovascular compression when compared with MRA. Preoperative knowledge of the compressing vessel has counselling implications and the higher risk of complications should be communicated to the patient. Due to cost and time implications we suggest that MR-CISS imaging replace the enhanced MRA sequence in the detailed preoperative MR assessment of hemifacial spasm.