Cone-beam CT versus multidetector CT in postoperative cochlear implant imaging: evaluation of image quality and radiation dose

Abstract

BACKGROUND AND PURPOSE: Cone-beam CT is being increasingly used in head and neck imaging. We compared cone-beam CT with multidetector CT to assess postoperative implant placement and delineate finer anatomic structures, image quality, and radiation dose used. MATERIALS AND METHODS: This retrospective multicenter study included 51 patients with cochlear implants and postoperative imaging via temporal bone cone-beam CT (n ¼ 32 ears) or multidetector CT (n ¼ 19 ears) between 2012 and 2017. We evaluated the visualization quality of single electrode contacts, the scalar position of the electrodes, cochlear walls, mastoid facial canal, metallic artifacts (using a 4-level visual score), and the ability to measure the insertion angle of the electrodes. The signal-to-noise ratio and radiation dose were also evaluated. RESULTS: Cone-beam CT was more sensitive for visualizing the scalar position of the electrodes (P ¼ .046), cochlear outer wall (P ¼ .001), single electrode contacts (P, .001), and osseous spiral lamina (P ¼ .004) and had fewer metallic artifacts (P, .001). However, there were no significant differences between both methods in visualization of the modiolus (P ¼ .37), cochlear inner wall (P . .99), and mastoid facial canal wall (P ¼ .07) and the ability to measure the insertion angle of the electrodes (P . .99). The cone-beam CT group had significantly lower dose-length product (P, .001), but multidetector CT showed a higher signal-to-noise ratio in both bone and air (P ¼ .22 and P ¼ .001). CONCLUSIONS: Cone-beam CT in patients with cochlear implants provides images with higher spatial resolution and fewer metallic artifacts than multidetector CT at a relatively lower radiation dose.