MR guided focused ultrasound: technical acceptance measures for a clinical system
MR guided focused ultrasound: technical acceptance measures for a clinical system
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DOI：
10.1088/0031-9155/51/12/011
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发表时间：
2006-06-21
影响因子：
3.5
通讯作者：
Felmlee, J. P.
中科院分区：
文献类型：
--
作者：
Gorny, K. R.;Hangiandreou, N. J.;Felmlee, J. P.
磁共振(MR)引导的聚焦超声(MRgFUS)是一种在MR引导和监测下提供高效、安全的聚焦超声(FUS)治疗子宫肌瘤的混合技术。作为一种治疗设备，MRgFUS在用于临床环境之前，需要对广泛的操作参数进行系统测试。我们介绍了第一个临床MRgFUS系统ExAblate(R)2000(InSightec Inc.，以色列海法)的技术验收测试和数据，该系统已被FDA批准用于治疗子宫肌瘤。这些测试通过在模拟体模的组织中使用磁共振温度测量来表征MRgFUS。经验证明，冠状扫描平面是测量高强度超声(US)脉冲(“声学”)引起的温度升高最可靠的方法，并且对声学参数的变化表现出很高的灵敏度。在冠状面测量的温度被用来测量在临床治疗中使用的一系列超声参数的焦点内沉积的超声能量：斑点类型、斑点长度、输出功率、超声持续时间、US频率和超声深度。此外，在超声检查过程中获得的MR图像被用来测量可用声化点类型和长度的有效直径和长度。在60W输出功率不变的情况下，测得有效光斑直径在4.7+/-0.3 mm~6.6+/-0.4 mm之间变化；随着光斑直径的增大，处理温度降低。研究发现，规定不同的光斑长度对测量长度或测量温度没有影响。MRgFUS定位精度测试确定平行于US波束传播方向的误差明显大于垂直方向的误差；大多数声化点被错误地定位到FUS换能器。这里报告的测试已经被证明足够灵敏，可以检测到FUS传感器内部的漏水。提供的数据可用于对其他临床MRgFUS系统进行验收测试的人员进行比较。
Magnetic resonance (MR) guided focused ultrasound (MRgFUS) is a hybrid technique which offers efficient and safe focused ultrasound (FUS) treatments of uterine fibroids under MR guidance and monitoring. As a therapy device, MRgFUS requires systematic testing over a wide range of operational parameters prior to use in the clinical environment. We present technical acceptance tests and data for the first clinical MRgFUS system, ExAblate (R) 2000 (InSightec Inc., Haifa, Israel), that has been FDA approved for treating uterine fibroids. These tests characterize MRgFUS by employing MR temperature measurements in tissue mimicking phantoms. The coronal scan plane is empirically demonstrated to be most reliable for measuring temperature elevations resulting from high intensity ultrasound (US) pulses ('sonications') and shows high sensitivity to changes in sonication parameters. Temperatures measured in the coronal plane were used as a measure of US energy deposited within the focal spot for a range of sonication parameters used in clinical treatments: spot type, spot length, output power, sonication duration, US frequency, and depth of sonication. In addition, MR images acquired during sonications were used to measure effective diameters and lengths of available sonication spot types and lengths. At a constant 60 W output power, the effective spot type diameters were measured to vary between 4.7 +/- 0.3 mm and 6.6 +/- 0.4 mm; treatment temperatures were found to decrease with increasing spot diameter. Prescribing different spot lengths was found to have no effect on the measured length or on measured temperatures. Tests of MRgFUS positioning accuracy determined errors in the direction parallel to the propagation of the US beam to be significantly greater than those in the perpendicular direction; most sonication spots were erroneously positioned towards the FUS transducer. The tests reported here have been demonstrated to be sufficiently sensitive to detect water leakage inside the FUS transducer. The data presented could be used for comparison by those conducting acceptance tests on other clinical MRgFUS systems.