Rata Mihaela, Birlea Vlad, Murillo Adriana, Paquet Christian, Cotton François, Salomir Rares
INSERM, Therapeutic Applications of Ultrasound, U556 (currently LabTAU - U1032), Université de Lyon, Lyon, F-69003, France.
Université de Lyon, Université Claude Bernard Lyon 1, Lyon, F-69003, France.
Magn Reson Med. 2015 Jan;73(1):417-26. doi: 10.1002/mrm.25099. Epub 2014 Jan 29.
MR-guided high-intensity contact ultrasound (HICU) was suggested as an alternative therapy for esophageal and rectal cancer. To offer high-quality MR guidance, two prototypes of receive-only opposed-solenoid coil were integrated with 64-element cylindrical phased-array ultrasound transducers (rectal/esophageal).
The design of integrated coils took into account the transducer geometry (360° acoustic window within endoluminal space). The rectal coil was sealed on a plastic support and placed reversibly on the transducer head. The esophageal coil was fully embedded within the transducer head, resulting in one indivisible device. Comparison of integrated versus external coils was performed on a clinical 1.5T scanner.
The integrated coils showed higher sensitivity compared with the standard extracorporeal coil with factors of up to 7.5 (rectal applicator) and 3.3 (esophageal applicator). High-resolution MR images for both anatomy (voxel 0.4 × 0.4 × 5 mm(3)) and thermometry (voxel 0.75 × 0.75 × 8 mm(3), 2 s/image) were acquired in vivo with the rectal endoscopic device. The temperature feedback loop accurately controlled multiple control points over the region of interest.
This study showed significant improvement of MR data quality using endoluminal integrated coils versus standard external coil. Inframillimeter spatial resolution and accurate feedback control of MR-guided HICU thermotherapy were achieved.
磁共振引导下的高强度接触式超声（HICU）被提议作为食管癌和直肠癌的一种替代治疗方法。为了提供高质量的磁共振引导，两种仅用于接收的对置螺线管线圈原型与64阵元圆柱形相控阵超声换能器（直肠/食管）集成在一起。
集成线圈的设计考虑了换能器的几何形状（腔内空间内360°的声学窗口）。直肠线圈密封在塑料支架上，并可逆地放置在换能器头部。食管线圈完全嵌入换能器头部，形成一个不可分割的装置。在临床1.5T扫描仪上对集成线圈和外部线圈进行了比较。
与标准体外线圈相比，集成线圈显示出更高的灵敏度，直肠应用器的灵敏度提高因子高达7.5，食管应用器的灵敏度提高因子为3.3。使用直肠内窥镜设备在体内获得了用于解剖（体素0.4×0.4×5 mm³）和温度测量（体素0.75×0.75×8 mm³，每幅图像2秒）的高分辨率磁共振图像。温度反馈回路精确地控制了感兴趣区域内的多个控制点。
本研究表明，与标准外部线圈相比，使用腔内集成线圈可显著提高磁共振数据质量。实现了亚毫米级的空间分辨率和磁共振引导下HICU热疗的精确反馈控制。
