Photon-counting CT as a potential new imaging modality for preoperative diagnosis of cochlear implantation

Imaging of the temporal bone is an essential part of postoperative diagnostics after cochlear implantation (CI). For this purpose, a multi-slice CT (MSCT) is usually performed to check the position of the inserted CI electrode. Photon-counting CT (PC-CT) is an imaging modality that could significantly reduce artifact generation and radiation exposure. The aim of this study was to investigate the suitability of PC-CT as a new diagnostic tool for evaluating the anatomical condition of the cochlea after CI and whether there are significant differences in image quality with respect to radiation dose. In this study, PC-CT imaging of 10 temporal bone specimen with inserted CI electrode (Flex 28) was performed. Each of these specimens received 8 images with different radiation doses. Subsequently, the cochlear duct length (CDL) was determined in each image by means of a 3D-dimensional reconstruction using OsiriX​ software. As a gold standard for CDL, micro-CT images of the 10 temporal bone specimens without an electrode were used. The deviations of CDLs measured in PC-CT compared to micro-CT were less than 1mm for all 8 different radiation doses per temporal bone. Upon closer examination of the 8 radiation doses in PC-CT, the results for the CDLs showed no significant difference between the lowest as well as the maximum radiation dose. PC-CT allows adequate measurement of the cochlea even with the lowest radiation dose. Therefore, more than 80% of the conventional radiation dose for CT imaging can be saved, which then corresponds to only about 2% of the natural annual exposure to background radiation. These findings may have an impact on radiological imaging in the context of CI surgery, as the radiation exposure with the new technique is almost negligible.

Publication History

Article published online:
12 May 2023