Department of Otolaryngology, Unfallkrankenhaus Berlin, Berlin, Germany.
Otol Neurotol. 2010 Dec;31(9):1435-40.
The goals of this study are to observe 1.5-T magnetic resonance imaging (MRI)-related changes to the Vibrant Soundbridge floating mass transducer (FMT) magnetization, function, and position in different coupling modes within the middle ear; changes to middle ear structures; and effects on the transfer function to the inner ear.
The MRI safety of implantable hearing devices is important in daily routine clinical care as well as in urgent care.
Nine FMTs were repeatedly investigated before and after MRI scanning. Changes in the position of the FMT (round window, incus, and stapes) and in the ossicular chain in temporal bones were estimated by microscopy, microendoscopy, and flat panel angiography. Functional investigations of the FMT in different coupling modes were done using laser Doppler vibrometry.
Qualitative demagnetization could be ruled out in all specimens after up to 11 MRI scans. In FMT couplings to the long process of the incus (n = 18), positional changes were found in 5 temporal bones. A disarticulation or exarticulation of the ossicles was not observed. Mean laser Doppler vibrometry measurements showed MRI-related changes in the stapes velocity. In FMT couplings to the round window (n = 23), we observed a fixation-dependent influence of MRI scanning on the FMT position and mean transfer function.
The functional integrity of the FMT was not significantly influenced after multiple MRI scans. Positional changes of the FMT within the middle ear are possible, but we observed no structural damage to middle ear structures. Effects on the transfer function are possible.
本研究的目的是观察 1.5-T 磁共振成像（MRI）相关的振动声桥浮动质量换能器（FMT）在中耳不同耦合模式下的磁化、功能和位置变化；中耳结构的变化；以及对内耳传递函数的影响。
植入式听力设备的 MRI 安全性在日常临床护理以及急救护理中都很重要。
对 9 个 FMT 进行了重复研究，分别在 MRI 扫描前后进行。通过显微镜、微内窥镜和平板血管造影术估计 FMT（圆窗、砧骨和镫骨）和颞骨中听小骨链的位置变化。使用激光多普勒测振仪对 FMT 在不同耦合模式下的功能进行了研究。
在所有标本中，经过多达 11 次 MRI 扫描后，均可排除定性退磁。在 FMT 与砧骨长突（n = 18）的耦合中，5 个颞骨中发现位置变化。未观察到听小骨分离或脱位。平均激光多普勒测振仪测量显示 MRI 相关的镫骨速度变化。在 FMT 与圆窗（n = 23）的耦合中，我们观察到 MRI 扫描对 FMT 位置和平均传递函数的固定依赖性影响。
多次 MRI 扫描后，FMT 的功能完整性未受到显著影响。FMT 在中耳内的位置变化是可能的，但我们未观察到中耳结构的结构损伤。对传递函数的影响是可能的。
