Reinfeldt Sabine, Östli Per, Håkansson Bo, Taghavi Hamidreza, Eeg-Olofsson Måns, Stalfors Joacim
*Department of Signals and Systems, Chalmers University of Technology, Gothenburg, Sweden; and †Ear, Nose, and Throat Department, Sahlgrenska University Hospital, Gothenburg, Sweden.
Otol Neurotol. 2015 Apr;36(4):631-7. doi: 10.1097/MAO.0000000000000682.
The aim was to assess the temporal bone volume to determine the suitable size and position of a bone conduction implant (BCI) transducer.
A BCI transducer needs to be sufficiently small to fit in the mastoid portion of the temporal bone for a majority of patients. The anatomical geometry limits both the dimension of an implanted transducer and its positions in the temporal bone to provide a safe and simple surgery.
Computed tomography (CT) scans of temporal bones from 22 subjects were virtually reconstructed. With an algorithm in MATLAB, the maximum transducer diameter as function of the maximum transducer depth in the temporal bone, and the most suitable position were calculated in all subjects.
An implanted transducer diameter of 16 mm inserted at a depth of 4 mm statistically fitted 95% of the subjects. If changing the transducer diameter to 12 mm, a depth of 6 mm would fit in 95% of the subjects. The most suitable position was found to be around 20 mm behind the ear canal.
The present BCI transducer casing, used in ongoing clinical trials, was designed from the results in this study, demonstrating that the present BCI transducer casing (largest diameter [diagonal]: 15.5 mm, height: 6.4 mm) will statistically fit more than 95% of the subjects. Hence, the present BCI transducer is concluded to be sufficiently small to fit most normal-sized temporal bones and should be placed approximately 20 mm behind the ear canal.
目的是评估颞骨体积，以确定骨传导植入物（BCI）换能器的合适尺寸和位置。
对于大多数患者而言，BCI换能器需要足够小，以便能安装在颞骨的乳突部分。解剖学结构限制了植入换能器的尺寸及其在颞骨中的位置，以确保手术安全且操作简单。
对22名受试者的颞骨进行计算机断层扫描（CT）并进行虚拟重建。利用MATLAB中的算法，计算出所有受试者中换能器最大直径与在颞骨中最大深度的函数关系，以及最合适的位置。
在深度为4mm处植入直径为16mm的换能器，在统计学上适合95%的受试者。如果将换能器直径改为12mm，深度为6mm时将适合95%的受试者。发现最合适的位置在耳道后方约20mm处。
目前正在进行临床试验中使用的BCI换能器外壳是根据本研究结果设计的，这表明目前的BCI换能器外壳（最大直径[对角线]：15.5mm，高度：6.4mm）在统计学上适合超过95%的受试者。因此，可以得出结论，目前的BCI换能器足够小，能够适合大多数正常尺寸的颞骨，并且应放置在耳道后方约20mm处。
