Department of Radiology, La Paz University Hospital, Madrid, Spain.
Department of Otorhinolaryngology, La Paz University Hospital, IdiPAZ Research Institute, Paseo de la Castellana, 261, 28046, Madrid, Spain.
Eur Arch Otorhinolaryngol. 2021 Sep;278(9):3203-3209. doi: 10.1007/s00405-020-06380-2. Epub 2020 Sep 23.
Analysis of head magnetic resonance images (MRI) of patients with active bone conduction implants (BCIs) is challenging. Currently, there are two generations of the transcutaneous Bonebridge system (BCI601 and BCI602), the main difference between them being the transducer design and thickness. The aim was to compare the effect of transducer placement and artifact reduction sequences on legibility of MRI scans.
Four Thiel-fixed human head specimens were used: BCI601 was implanted in sinodural and middle fossa placement, and BCI602 in middle fossa and retrosigmoid approach. Images were obtained with a Signa 1.5T MR. A metal artifact reduction sequence known as MAVRIC (multiacquisition variable-resonance image combination) was used. Each specimen was scanned using standard axial T2 SE and compared with axial MAVRIC artifact reduction sequences.
Qualitatively, limits of the artifact produced by the implant were better defined with MAVRIC than with standard T2 sequences. Assessment of contralateral internal auditory canal (IAC) was possible in all cases. Placement of the BCI602 in the middle fossa allowed the view of the ipsilateral IAC using MAVRIC sequence. Quantitatively, the artifact was reduced with MAVRIC sequence from 6.3 to 59.7%, depending on the position of implant and model; the middle fossa placement and the BCI602 being those generating shorter artifact radio.
Artifact optimized sequences as MAVRIC reduce the artifact caused by the Bonebridge system. The middle fossa approach allows a better visualization of IAC canal in the ipsilateral ear with both implant versions, but the effect is more prominent with the BCI602.
分析活性骨导植入物（BCI）患者的头部磁共振图像（MRI）具有挑战性。目前有两代经皮 Bonebridge 系统（BCI601 和 BCI602），它们之间的主要区别在于换能器设计和厚度。目的是比较换能器放置和伪影减少序列对 MRI 扫描可读性的影响。
使用 4 个 Thiel 固定的人头标本：BCI601 植入硬脑膜窦和中颅窝，BCI602 植入中颅窝和乙状窦后。使用 Signa 1.5T MR 获得图像。使用称为 MAVRIC（多采集可变共振图像组合）的金属伪影减少序列。对每个标本进行标准轴向 T2 SE 扫描，并与轴向 MAVRIC 伪影减少序列进行比较。
定性地，与标准 T2 序列相比，MAVRIC 更好地定义了植入物产生的伪影的边界。在所有情况下都可以评估对侧内听道（IAC）。在中颅窝中放置 BCI602 可以使用 MAVRIC 序列观察到同侧 IAC。定量地，MAVRIC 序列将伪影减少了 6.3%至 59.7%，具体取决于植入物和模型的位置；中颅窝位置和 BCI602 产生的伪影较短。
优化伪影的序列，如 MAVRIC，可以减少 Bonebridge 系统引起的伪影。中颅窝入路允许两种植入物版本更好地观察同侧耳的 IAC 管，但 BCI602 的效果更为明显。
