Institut Langevin, ESPCI ParisTech, CNRS UMR 7587, INSERM U979, Université Paris VII, Laboratoire Ondes et Acoustique, 10 Rue Vauquelin, 75231 Paris Cedex 05, France.
Phys Med Biol. 2011 Nov 21;56(22):7061-80. doi: 10.1088/0031-9155/56/22/005. Epub 2011 Oct 21.
Recent studies have demonstrated the feasibility of transcostal high intensity focused ultrasound (HIFU) treatment in liver. However, two factors limit thermal necrosis of the liver through the ribs: the energy deposition at focus is decreased by the respiratory movement of the liver and the energy deposition on the skin is increased by the presence of highly absorbing bone structures. Ex vivo ablations were conducted to validate the feasibility of a transcostal real-time 3D movement tracking and correction mode. Experiments were conducted through a chest phantom made of three human ribs immersed in water and were placed in front of a 300 element array working at 1 MHz. A binarized apodization law introduced recently in order to spare the rib cage during treatment has been extended here with real-time electronic steering of the beam. Thermal simulations have been conducted to determine the steering limits. In vivo 3D-movement detection was performed on pigs using an ultrasonic sequence. The maximum error on the transcostal motion detection was measured to be 0.09 ± 0.097 mm on the anterior-posterior axis. Finally, a complete sequence was developed combining real-time 3D transcostal movement correction and spiral trajectory of the HIFU beam, allowing the system to treat larger areas with optimized efficiency. Lesions as large as 1 cm in diameter have been produced at focus in excised liver, whereas no necroses could be obtained with the same emitted power without correcting the movement of the tissue sample.
最近的研究表明，经肋骨的高强度聚焦超声（HIFU）治疗肝脏是可行的。然而，有两个因素限制了通过肋骨实现肝脏的热坏死：肝脏的呼吸运动会降低焦点处的能量沉积，而存在高度吸收的骨结构会增加皮肤处的能量沉积。进行了离体消融实验以验证经肋骨实时 3D 运动跟踪和校正模式的可行性。实验是在一个由浸入水中的三根人肋骨制成的胸腔模型中进行的，该模型放置在工作频率为 1MHz 的 300 个阵元阵列前。这里扩展了最近引入的一种为了在治疗过程中避免肋骨笼的二进制变迹律，并实时电子引导波束。进行了热模拟以确定转向限制。使用超声序列对猪进行了体内 3D 运动检测。在经肋骨运动检测的最大误差方面，在前-后轴上测量为 0.09 ± 0.097mm。最后，开发了一个完整的序列，结合实时 3D 经肋骨运动校正和 HIFU 束的螺旋轨迹，使系统能够以优化的效率治疗更大的区域。在离体肝脏中，在焦点处产生了直径达 1cm 的病变，而在不校正组织样本运动的情况下，用相同的发射功率无法获得坏死。
