脂肪及肌肉组织对高强度聚焦超声消融能量沉积及焦域形态的影响

Effects of fat and muscle tissue on MR-guided high-intensity focused ultrasound ablation energy deposition and focus shape

目的比较高强度聚焦超声(HIFU)通过不同厚度脂肪及肌肉组织消融猪肉靶点时的能量衰减情况。方法在MRI监控下分别选择脂肪厚度为0 mm、20 mm、28 mm的猪肉靶点,以输出功率200 W、辐照时间10 s进行单点消融,比较相同辐照条件下所产生的凝固性坏死体积。进一步选择脂肪厚度25 mm带皮猪肉及无皮和脂肪猪肉,分别将焦点置于距肌肉表面深度20 mm、30 mm的靶点进行单点辐照。结果随着脂肪厚度的增加,相同辐照条件下产生凝固性坏死区体积逐渐缩小,长轴逐渐增加,短轴逐渐缩小。当辐照无脂肪的猪肉组织时,随肌肉厚度的增加,损伤体积缩小;但相同厚度的脂肪组织对超声能量的衰减大于肌肉组织。结论 HIFU通过离体脂肪组织、肌肉组织时均有能量衰减;脂肪组织对超声能量的衰减程度高于肌肉组织。

Objective To compare the acoustic attenuation of high-intensity focused ultrasound（HIFU） energy within the pork when through different thickness of fat and muscle tissue. Methods All the processes were monitored under MRI. The pork with different thickness of fat（0 mm,20 mm,28 mm） were selected. The focus of HIFU was placed at the same distance from the superficial and sonicated with the same power of 200 W for 10 s. The necrosis regions were compared. Then the pork with 25 mm thickness of fat was selected,and the focus was placed at 20 mm,30 mm away from the muscle surface and sonicated with 200 W of power for 10 s. After that,skin and fat-free pork was selected. Focus was placed at 20 mm,30 mm away from the muscle surface and sonicated with the same power for 10 s. Results With the increase of fat thickness under the same sonication condition,the volume of coagulation necrosis region gradually reduced,the long axis of coagulation necrosis area gradually increased,and the minor axis gradually narrowed. When treat fat free pork under the same sonication condition,with the increase of the thickness of the muscle,the damage volume reduced. The fat tissue has more acoustic attenuation effects on HIFU than the muscle tissue. Conclusion The acoustic attenuation effects occur when HIFU pass the fat tissue or the muscle tissue. Fat tissue has more acoustic attenuation effects than the muscle tissue.