Magda Abbas A, Constatin-Coussios C, Robin Cleveland O
Annu Int Conf IEEE Eng Med Biol Soc. 2018 Jul;2018:5709-5712. doi: 10.1109/EMBC.2018.8513647.
High Intensity Focussed Ultrasound (HIFU) is emerging as a non-invasive treatment for localised renal tumours. However, challenges remain in the delivery of the treatment to tumours at depth, with clinical results showing a variation in the ablation efficacy. One clinical trial conducted at the Churchill hospital, Oxford, to investigate the applicability of HIFU for renal tumour ablation found that in 4/10 patients less than 5% of the tumour volume was ablated successfully. The current study looks at the role tissue geometry has on the resulting focal pressure and focal heating. CT scans from 4 patients within the trial were selected, who experienced 70%, < 5%, < 5% and 95% ablation of the target tumour. The CT scans were segmented into bone, fat, kidney, and generic tissue. Full three-dimensional ultrasound simulations were carried out using k-Wave (an open source Matlab toolbox) and for three patients a tight focus was achieved in the kidney but peak pressures varied by 20%. While in the fourth patient there was significant fragmentation of the -6 dB focal volume due to the intervening ribcage. Thermal simulations were used to compare the temperature rise induced across the different patient models. For the three patients with a tight focus, the predicted 47°C iso-volume of the patient with 70% ablation was 2-3 times larger than the two patients with < 5% ablation. For the patient in which the ribcage resulted in focal fragmentation the thermal simulation predicted just a 1°C temperature rise.
高强度聚焦超声（HIFU）正在成为一种治疗局部肾肿瘤的非侵入性方法。然而，将该治疗应用于深部肿瘤仍存在挑战，临床结果显示消融效果存在差异。在牛津丘吉尔医院进行的一项调查HIFU用于肾肿瘤消融适用性的临床试验发现，在10名患者中有4名患者的肿瘤体积成功消融不到5%。当前研究着眼于组织几何形状对产生的焦点压力和焦点加热的作用。从该试验中的4名患者选取CT扫描图像，这4名患者的目标肿瘤消融率分别为70%、<5%、<5%和95%。CT扫描图像被分割为骨骼、脂肪、肾脏和一般组织。使用k-Wave（一个开源的Matlab工具箱）进行全三维超声模拟，对于三名患者，在肾脏中实现了紧密聚焦，但峰值压力相差20%。而在第四名患者中，由于中间的肋骨，-6dB焦点体积出现了明显的碎片化。使用热模拟来比较不同患者模型中引起的温度升高。对于三名实现紧密聚焦的患者，消融率为70%的患者预测的47°C等体积比另外两名消融率<5%的患者大2至3倍。对于肋骨导致焦点碎片化的患者，热模拟预测温度仅升高1°C。
