Cline H E, Schenck J F, Watkins R D, Hynynen K, Jolesz F A
General Electric Corporate Research and Development, Schenectady, NY 12301.
Magn Reson Med. 1993 Jul;30(1):98-106. doi: 10.1002/mrm.1910300115.
A demonstration of MR guided thermal surgery involved experiments with imaging of focused ultrasound in an MRI system, measurements of the thermal transients and a thermal analysis of the resulting images. Both the heat distribution and the creation of focused ultrasound lesions in gel phantoms, in vitro bovine muscle and in vivo rabbit muscle were monitored with magnetic resonance imaging. Thermal surgical procedures were modeled by an elongated gaussian heat source where heat flow is controlled by tissue thermal properties and tissue perfusion. Temperature profiles were measured with thermocouples or calculated from magnetic resonance imaging in agreement with the model. A 2-s T1-weighted gradient-refocused acquisition provided thermal profiles needed to localize the heat distribution produced by a 4-s focused ultrasound pulse. Thermal analysis of the images give an effective thermal diffusion coefficient of 0.0015 cm2/s in gel and 0.0033 cm2/s in muscle. The lesions were detected using a T2-weighted spin-echo or fast spin-echo pulse sequence in agreement with muscle tissue sections. Potential thermal surgery applications are in the prostate, liver, kidney, bladder, breast, eye and brain.
磁共振引导热手术的演示涉及在磁共振成像系统中对聚焦超声进行成像的实验、热瞬态测量以及对所得图像的热分析。利用磁共振成像监测了凝胶体模、体外牛肌肉和体内兔肌肉中的热分布以及聚焦超声损伤的形成。热外科手术过程由一个细长的高斯热源建模，其中热流由组织热特性和组织灌注控制。温度分布用热电偶测量，或根据磁共振成像并与模型一致进行计算。一个2秒的T1加权梯度重聚焦采集提供了定位由4秒聚焦超声脉冲产生的热分布所需的热分布。图像的热分析得出凝胶中的有效热扩散系数为0.0015平方厘米/秒，肌肉中的为0.0033平方厘米/秒。使用T2加权自旋回波或快速自旋回波脉冲序列检测损伤，结果与肌肉组织切片一致。热手术的潜在应用部位包括前列腺、肝脏、肾脏、膀胱、乳房、眼睛和大脑。
