Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
Magn Reson Med. 2023 Dec;90(6):2608-2626. doi: 10.1002/mrm.29818. Epub 2023 Aug 2.
To investigate a novel reduced RF heating method for imaging in the presence of active implanted medical devices (AIMDs) which employs a sensor-equipped implant that provides wireless feedback.
The implant, consisting of a generator case and a lead, measures RF-induced -fields at the implant tip using a simple sensor in the generator case and transmits these values wirelessly to the MR scanner. Based on the sensor signal alone, parallel transmission (pTx) excitation vectors were calculated to suppress tip heating and maintain image quality. A sensor-based imaging metric was introduced to assess the image quality. The methodology was studied at 7T in testbed experiments, and at a 3T scanner in an ASTM phantom containing AIMDs instrumented with six realistic deep brain stimulation (DBS) lead configurations adapted from patients.
The implant successfully measured RF-induced -fields (Pearson correlation coefficient squared [R ] = 0.93) and temperature rises (R = 0.95) at the implant tip. The implant acquired the relevant data needed to calculate the pTx excitation vectors and transmitted them wirelessly to the MR scanner within a single shot RF sequence (<60 ms). Temperature rises for six realistic DBS lead configurations were reduced to 0.03-0.14 K for heating suppression modes compared to 0.52-3.33 K for the worst-case heating, while imaging quality remained comparable (five of six lead imaging scores were ≥0.80/1.00) to conventional circular polarization (CP) images.
Implants with sensors that can communicate with an MR scanner can substantially improve safety for patients in a fast and automated manner, easing the current burden for MR personnel.
研究一种新的降低射频加热方法，用于在有源植入式医疗器械（AIMD）存在下进行成像，该方法采用带有无线反馈功能的传感器植入物。
该植入物由发生器外壳和导线组成，使用发生器外壳中的简单传感器测量植入物尖端的射频感应 B 场，并将这些值无线传输到磁共振扫描仪。仅基于传感器信号，计算了并行传输（pTx）激励矢量，以抑制尖端加热并保持图像质量。引入了基于传感器的成像指标来评估图像质量。该方法在 7T 测试平台实验中进行了研究，并在包含 6 种由患者适配的真实深部脑刺激（DBS）导线配置的 AIMD 的 ASTM 体模的 3T 扫描仪上进行了研究。
植入物成功测量了植入物尖端的射频感应 B 场（Pearson 相关系数平方 [R]²=0.93）和温度升高（R²=0.95）。植入物获取了计算 pTx 激励矢量所需的相关数据，并在单个射频序列中（<60ms）无线传输给磁共振扫描仪。与最差加热情况下的 0.52-3.33K 相比，对于六种真实 DBS 导线配置，加热抑制模式下的温度升高降低到 0.03-0.14K，而成像质量仍然与传统圆极化（CP）图像相当（六个导线成像评分中有五个为≥0.80/1.00）。
带有可以与磁共振扫描仪进行通信的传感器的植入物可以以快速和自动化的方式显著提高患者的安全性，减轻磁共振工作人员的当前负担。
