Cone-beam CT versus Multidetector CT in Postoperative Cochlear Implant Imaging: Evaluation of Image Quality and Radiation Dose.

Abstract

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. This retrospective multicenter study included 51 patients with cochlear implants and postoperative imaging via temporal bone cone-beam CT (n = 32 ears) or multidetector CT (n = 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. Cone-beam CT was more sensitive for visualizing the scalar position of the electrodes (P = .046), cochlear outer wall (P = .001), single electrode contacts (P < .001), and osseous spiral lamina (P = .004) and had fewer metallic artifacts (P < .001). However, there were no significant differences between both methods in visualization of the modiolus (P = .37), cochlear inner wall (P > .99), and mastoid facial canal wall (P = .07) and the ability to measure the insertion angle of the electrodes (P > .99). The conebeam 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 = .22 and P = .001). 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.