High resolution 3-T MR imaging in the evaluation of the facial nerve course

OBJECTIVES To assess the value of 3-Tesla (3-T) MR imaging (MRI) in the evaluation of the course of the intracranial and extra-cranial tracts of the facial nerve. PATIENTS AND METHODS 83 patients were studied by MRI in order to detect the course of facial nerve; a total of 166 facial nerves were examined. T2-weighted 3D Fast imaging employing steady-state acquisition (FIESTA) and T1-weighted Fast spoiled gradient recalled echo (fast SPRG) sequences were used. Two radiologists (reader A and B), independently, evaluated the course of the tracts of the facial nerve according to a qualitative scale (excellent, good, fair, poor). The Intraclass Correlation Coefficient (ICC) and Pearson correlation coefficient were used to assess the intra-observer and interobserver variability in the nerve course evaluation. RESULTS Reader A evaluated 35 facial nerves as excellent, 94 as good, 33 as fair and 4 as poor. Reader B rated 31 facial nerves excellent, 89 good, 43 fair and 3 poor. The intraobserver variability was ICC = 0.919 in reader A and ICC = 0.842 in reader B. The interobserver variability (Pearson correlation coefficient) was 0.713 (p ≤ 0.01). CONCLUSIONS According to the preliminary results of our study the use of 3-T MRI with FIESTA and fast SPGR sequences may allow the study of the course of the facial nerve and its branches. The knowledge of the course and of the anatomic relationships of these nerve bundles with surrounding structures, as well as of the anatomical variants, provide useful informations for a prompt neurosurgery and maxillofacial surgical planning.