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 4level 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 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 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.

High-speed flat-detector computed tomography for temporal bone imaging and postoperative control of cochlear implants

“…In agreement with several previous studies [ 13 , 16 – 18 ] and due to their superior spatial resolution and low susceptibility for metal artifacts, both FD-CT systems yield better image quality than MS-CT for evaluation of the microanatomical details of the temporal bone and the precise cochlear implant position: in our study, the HS-FD-CT with its 14-s scanning protocol provided the best visualization of the temporal bone specimens and the CI, followed closely by the FD-CT using the 20 s 70 kV and 109 kV protocol and the 9 s HS-FD-CT protocol. Although providing worst IQ among tested (HS-)FD-CT protocols, the 7 s HS-FD-CT protocol still exceeds MS-CT.…”

“…Because of its affordable price compared to angiography systems, lighter and smaller equipment, better spatial resolution compared to MS-CT and equal spatial resolution compared to FD-CT, the simplicity to operate and maintain, the possibility to scan seated patients and the open design to help claustrophobic patients [ 25 ], CB-CT is the preferred imaging modality for dental and maxillofacial skeleton imaging [ 25 ] and is also applicable for temporal bone imaging as well as postoperative cochlear implant control. In this context, CB-CT significantly reduces radiation dose compared to MS-CT and FD-CT [ 26 ]: for example, in a recent study, Helal et al report a median DLP of 93 mGycm for CBCT in comparison to a median DLP of 387.5 mGycm for MS-CT [ 13 ]. In this context, Burck et al measured the effective dose of CBCT in comparison to MS-CT and found an effective dose reduction of up to 97.7% via CBCT [ 12 ].…”

“…Imaging of the temporal bone with its diminutive anatomical structures remains a radiologic challenge, even more complicated by metal artifacts due to the electrode array of the CI. Combining impressive image quality and lower radiation dose than multi-slice computed tomography (MS-CT) with an affordable price, cone beam computed tomography (CBCT)—a system equipped with an X-ray source and a contralateral mounted flat panel detector rotating around the patient’s head for image acquisition [ 11 ]—is the preferred image modality not only for postoperative CI control [ 12 , 13 ] but also for dental and maxillofacial imaging [ 14 ]. However, in contrast to its common availability in smaller hospitals, dedicated CBCT scanners are still not widely available in specialized departments of neuroradiology [ 15 ].…”

Radiologische Diagnostik bei Schwerhörigkeit im Kindesalter

“…Heute hat die DVT in vielen Zentren die CT aufgrund ihrer relativ geringeren metallischen Artefakte und Strahlenexposition ersetzt (▶ Abb. 13)[18].…”

Measuring 3D Cochlear Duct Length on MRI: Is It Accurate and Reliable?

“…2 However, the radiation exposure in these CT-based measurements is a consideration; therefore, it is desirable to use alternate imaging methods like MR imaging to make these measurements. 10 This study aimed to test the accuracy and reliability of MR imaging-based 3D cochlear length measurements that were previously performed by CT. A secondary aim was to test the effect of the observer's experience on these measurements.…”