European Institute for ORL-HNS, GZA Sint-Augustinus, Antwerp, Belgium.
European Institute for ORL-HNS, GZA Sint-Augustinus, Antwerp, Belgium.
Hear Res. 2022 Dec;426:108537. doi: 10.1016/j.heares.2022.108537. Epub 2022 May 25.
Positioning of the cochlear implant (CI) electrode in relation to the anatomical structures is a key factor for the hearing outcome and the preservation of residual hearing after cochlear implantation. Determining the exact electrode's location is therefore expected to play an important role in optimisation of the electrode design, the surgical techniques and the post-operative device fitting. The aim of this study is the development and validation of a robust and efficient computerised algorithm for three-dimensional (3D) localisation of the CI-electrode contacts with respect to the relevant cochlear structures, such as the basilar membrane and the modiolus, from modern clinical in vivo cone-beam computed tomography (CBCT). In the presented algorithm, the pre- and post-implantation CBCT are spatially aligned. To localise the anatomical structures, a cochlear microanatomical template derived from lab-based X-ray computed microtomography (µCT) measurements is warped to match the patient-specific cochlear shape acquired from pre-implantation CBCT. The electrode-contact locations, determined from the post-operative CBCT, are superimposed onto the cochlear fine-structure of the microanatomical template to localise the array. The accuracy of this method was validated in a temporal bone study by comparing the distance of the electrode contacts from the modiolar wall, as derived by the algorithm from CBCTs, with the distance determined from synchrotron-radiation (SR) µCT on the same specimens. Due to the achievable spatial resolution, good tissue contrast and limited presence of metallic artifacts, the SRµCT technique is considered to be a golden standard in the proposed approach. In contrast to other approaches, this validation method allowed for the evaluation of the final electrode-to-modiolus distance (EMD) error, and covers the error in co-alignment of the images, in the determination of the electrode contact location and in the localisation of the cochlear structures. The absolute mean error on the EMD parameter was determined at 0.11 mm (max = 0.29 mm, SD = 0.07 mm) across five samples, slightly lower than the voxel size of the CBCT-scans. In a retrospective study, the algorithm was applied to identify scalar translocations of the electrode from clinical in vivo CBCT datasets of 23 CI-recipients, which showed perfect (100%) agreement with the blinded opinion of two experienced neuroradiologists.
人工耳蜗电极在解剖结构中的定位是听力结果和人工耳蜗植入后残余听力保护的关键因素。因此，确定电极的确切位置有望在优化电极设计、手术技术和术后设备适配方面发挥重要作用。本研究的目的是开发和验证一种稳健、高效的计算机算法，用于根据现代临床体内锥形束计算机断层扫描（CBCT）确定人工耳蜗电极触点相对于基底膜和中轴等相关耳蜗结构的三维（3D）定位。在提出的算法中，对植入前和植入后的 CBCT 进行空间配准。为了定位解剖结构，从基于实验室的 X 射线计算机断层扫描（µCT）测量中获得的耳蜗微观解剖模板被扭曲以匹配从植入前 CBCT 获得的患者特定耳蜗形状。从术后 CBCT 确定的电极接触位置叠加到微解剖模板的耳蜗精细结构上以定位数组。该方法的准确性在颞骨研究中通过比较算法从 CBCT 中得出的电极接触与从同一标本的同步辐射（SR）µCT 确定的电极接触与中轴壁的距离来验证。由于可达到的空间分辨率、良好的组织对比度和有限的金属伪影存在，SRµCT 技术被认为是所提出方法的金标准。与其他方法相比，这种验证方法允许评估最终电极到中轴的距离（EMD）误差，并涵盖图像配准、电极接触位置确定和耳蜗结构定位中的误差。在五个样本中，EMD 参数的绝对平均误差确定为 0.11 毫米（最大为 0.29 毫米，SD 为 0.07 毫米），略低于 CBCT 扫描的体素大小。在回顾性研究中，该算法应用于从 23 名人工耳蜗接受者的临床体内 CBCT 数据集识别电极的标量移位，与两位经验丰富的神经放射科医生的盲法意见完全一致（100%）。
