Quantitative assessment of intraparotid facial nerve visibility using 3D-DESS-WE MRI: a retrospective study
摘要
Preserving the intraparotid facial nerve is a crucial aspect of parotid gland surgery to avoid postoperative facial paralysis. While three-dimensional double-echo steady-state with water excitation magnetic resonance imaging has been utilized to directly visualize the nerve, quantitative assessments of its visibility across different branch levels are lacking. This study aimed to quantitatively evaluate the visibility of the intraparotid facial nerve and its branches using this specific magnetic resonance imaging sequence.
MethodsThis retrospective study enrolled twenty-two patients with parotid gland tumors who underwent preoperative scanning on a 3.0T scanner. The intraparotid facial nerve was traced and divided into eight specific segments: the main trunk, two primary branches (temporofacial and cervicofacial), and five secondary branches (temporal, zygomatic, superior buccal, inferior buccal, and marginal mandibular). Two observers measured quantitative visibility parameters, including detection rate, signal intensity, signal-to-noise ratio, and signal-to-intensity ratio. Statistical analyses, including Fisher’s exact test and one-way analysis of variance, were performed to compare differences among the nerve segments.
ResultsThe main trunk of the facial nerve demonstrated the best visibility with a 100% detection rate. The primary branches also showed high visibility, with a detection rate of 90.9% for both the cervicofacial and temporofacial trunks. Conversely, the secondary branches exhibited significantly lower visibility, with a mean detection rate of 55.5%. Among these, the marginal mandibular branch had the lowest detection rate at 36.4%. There were statistically significant differences in signal intensity, signal-to-noise ratio, and signal-to-intensity ratio between the main trunk, primary branches, and secondary branches.
ConclusionsThree-dimensional double-echo steady-state with water excitation magnetic resonance imaging offers excellent visualization of the main trunk and primary branches of the intraparotid facial nerve. However, the visibility of secondary, terminal branches is relatively poor. Improvements in image post-processing algorithms are necessary to enhance the visualization of thinner terminal branches to better assist in surgical planning.