Peng Hsu-Hsia, Huang Teng-Yi, Tseng Wen-Yih Isaac, Lin En-Li, Chung Hsiao-Wen, Wu Chih-Ching, Wang Yu-Shun, Chen Wen-Shiang
Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan.
J Magn Reson Imaging. 2009 Sep;30(3):596-605. doi: 10.1002/jmri.21860.
To measure temperature change and magnetization transfer ratio (MTR) simultaneously during high-intensity focused ultrasound (HIFU) treatment.
This study proposed an interleaved dual gradient-echo technique to monitor the heat and tissue damage brought to the heated tissue. The technique was applied to tissue samples to test its efficacy.
Ex vivo experiments on the porcine muscle demonstrated that both temperature changes and MTR exhibited high consistency in localizing the heated regions. As the heat dissipated after the treatment, the temperature of the heated regions decreased rapidly but MTR continued to be elevated. Moreover, thermal dose (TD) maps derived from the temperature curves demonstrated a sharp margin in the heated regions, but MTR maps may show a spatial gradient of tissue damage, suggesting complimentary information provided by these two measures.
In a protocol of spot-by-spot heating over a large volume of tissue, MTR provides additional values to mark the locations of previously heated regions. By continuously recording the locations of heated spots, MTR maps could help plan the next target spots appropriately, potentially improving the efficiency of HIFU treatment and reducing undesirable damage to the normal tissue.
在高强度聚焦超声（HIFU）治疗过程中同时测量温度变化和磁化传递率（MTR）。
本研究提出一种交错双梯度回波技术，以监测加热组织所产生的热量和组织损伤。该技术应用于组织样本以测试其有效性。
对猪肌肉的离体实验表明，温度变化和MTR在定位加热区域方面表现出高度一致性。治疗后热量消散时，加热区域的温度迅速下降，但MTR仍持续升高。此外，从温度曲线得出的热剂量（TD）图在加热区域显示出清晰的边界，但MTR图可能显示出组织损伤的空间梯度，表明这两种测量方法提供了互补信息。
在对大量组织进行逐点加热的方案中，MTR为标记先前加热区域的位置提供了额外价值。通过持续记录加热点的位置，MTR图有助于合理规划下一个目标点，有可能提高HIFU治疗的效率并减少对正常组织的不良损伤。
