Auboiroux Vincent, Petrusca Lorena, Viallon Magalie, Muller Arnaud, Terraz Sylvain, Breguet Romain, Montet Xavier, Becker Christoph D, Salomir Rares
Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland ; Clinatec/LETI/CEA, 38054 Grenoble, France.
Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland.
Biomed Res Int. 2014;2014:421726. doi: 10.1155/2014/421726. Epub 2014 Jan 29.
To demonstrate the technical feasibility and the potential interest of using a digital optical camera inside the MR magnet bore for monitoring the breathing cycle and subsequently gating the PRFS MR thermometry, MR-ARFI measurement, and MRgHIFU sonication in the upper abdomen.
A digital camera was reengineered to remove its magnetic parts and was further equipped with a 7 m long USB cable. The system was electromagnetically shielded and operated inside the bore of a closed 3T clinical scanner. Suitable triggers were generated based on real-time motion analysis of the images produced by the camera (resolution 640 × 480 pixels, 30 fps). Respiratory-gated MR-ARFI prepared MRgHIFU ablation was performed in the kidney and liver of two sheep in vivo, under general anaesthesia and ventilator-driven forced breathing.
The optical device demonstrated very good MR compatibility. The current setup permitted the acquisition of motion artefact-free and high resolution MR 2D ARFI and multiplanar interleaved PRFS thermometry (average SNR 30 in liver and 56 in kidney). Microscopic histology indicated precise focal lesions with sharply delineated margins following the respiratory-gated HIFU sonications.
The proof-of-concept for respiratory motion management in MRgHIFU using an in-bore digital camera has been validated in vivo.
证明在磁共振成像（MR）磁体孔腔内使用数字光学相机监测呼吸周期，并随后对腹部上区的相位分辨频率选择饱和（PRFS）MR温度测量、MR声辐射力成像（MR-ARFI）测量以及磁共振引导高强度聚焦超声（MRgHIFU）超声治疗进行门控的技术可行性和潜在价值。
对一台数字相机进行改造，去除其磁性部件，并进一步配备一根7米长的USB电缆。该系统进行了电磁屏蔽，并在一台封闭的3T临床扫描仪的磁体孔腔内运行。基于相机所产生图像（分辨率640×480像素，30帧/秒）的实时运动分析生成合适的触发信号。在全身麻醉和呼吸机驱动的强制呼吸条件下，对两只绵羊的肾脏和肝脏进行了呼吸门控的MR-ARFI准备的MRgHIFU消融。
该光学设备显示出非常好的MR兼容性。当前设置允许获取无运动伪影且高分辨率的MR二维ARFI和多平面交错PRFS温度测量（肝脏平均信噪比为30，肾脏为56）。微观组织学显示，呼吸门控的HIFU超声治疗后出现了边缘清晰的精确局灶性病变。
使用孔腔内数字相机进行MRgHIFU呼吸运动管理的概念验证已在体内得到验证。
