Improved visualization of the chorda tympani nerve using ultra‐high-resolution computed tomography
Masahiro Fujiwara, Yoshiyuki Watanabe, Nobuo Kashiwagi, Yumi Ohta, Takashi Sato, Megumi Nishigaki, Noriyuki Tomiyama
Abstract
Background Recognition of the anatomical course of the chorda tympani nerve (CTN) is important for preventing iatrogenic injuries during middle-ear surgery. Purpose This study aims to compare visualization of the CTN using two computed tomography (CT) methods: conventional high-resolution CT (C-HRCT) and ultra‐high-resolution CT (U-HRCT). Materials and methods We performed a retrospective visual assessment of 59 CTNs in normal temporal bones of 54 consecutive patients who underwent both C-HRCT and U-HRCT. After dividing CTN into three anatomical segments (posterior canaliculus, tympanic segment, and anterior canaliculus), two neuroradiologists scored the visualizations on a four-point scale. Results On C-HRCT, the visual scores of the posterior canaliculus, tympanic segment, and anterior canaliculus were 3.5 ± 0.7, 1.6 ± 0.6, and 3.1 ± 0.7, respectively. The respective values were significantly higher in all segments on U-HRCT: 3.9 ± 0.2, 2.4 ± 0.6, 3.5 ± 0.6 ( p < 0.01). Although the difference in scores between methods was greatest for the tympanic segment, the visual score on U-HRCT was lower for the tympanic segment than for the anterior and posterior segments ( p < 0.01). Conclusion Ultra‐high-resolution CT provides superior visualization of the CTN, especially the tympanic segment.