High-intensity focused ultrasound (HIFU) has been used for noninvasive treatment of breast tumors, but the present magnetic resonance imaging (MRI)-guided HIFU (MRI-HIFU) systems encounter skin burn. In this study, a novel MRI-HIFU breast ablation system was developed to improve the above problem. The system consisted of the ring HIFU phased-array transducer, a commercial power amplifier, the mechanical positioner, and the graphical user interface control software. MRI thermometry was also established to monitor the temperature in the HIFU-treated tissue. Ablation of pork and the in vivo rabbit leg were carried out to validate the developed system. Results of fat-surrounding pork ablation showed that the ring HIFU system reached a safe margin of 3 mm without fat burn. Moreover, precision of the positioner moving the HIFU focal zone was within 6% error under MRI circumstances. The representative MRI temperature images show that the peak temperatures among the five ablations ranged between 66 °C and 91 °C, and their thermal doses were over 10000. The system could also ablate the biceps femoris of a rabbit without skin burn to form a lesion of 2.5 mm beneath the skin. With the HIFU dose of 315 W/10 s, the MRI temperature map revealed that the maximum temperature and the thermal dose were 60 °C and 3380, respectively. The MRI-guided ring HIFU system can ablate the target tissue near subcutaneous fat without fat burn. The system prototype is a promising tool for clinical implementation.

中文翻译：

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MRI引导环高强度聚焦超声治疗无创性乳房消融

高强度聚焦超声（HIFU）已用于乳腺肿瘤的非侵入性治疗，但是目前的磁共振成像（MRI）引导的HIFU（MRI-HIFU）系统遇到皮肤灼伤。在这项研究中，开发了一种新型的MRI-HIFU乳房消融系统来改善上述问题。该系统由环形HIFU相控阵传感器，商用功率放大器，机械定位器和图形用户界面控制软件组成。还建立了MRI测温法以监测HIFU处理的组织中的温度。烧猪肉和体内兔腿进行了验证，以开发系统。猪肉周围脂肪消融的结果表明，环形HIFU系统达到了3 mm的安全裕度，没有脂肪燃烧。而且，在MRI情况下，定位器移动HIFU聚焦区的精度误差在6％以内。代表性的MRI温度图像显示，五个消融之间的峰值温度在66°C和91°C之间，并且其热剂量超过10000。该系统还可消融没有皮肤灼伤的兔股二头肌，从而形成病变。在皮肤下面2.5毫米 HIFU剂量为315 W / 10 s，MRI温度图显示最高温度和热剂量分别为60°C和3380。MRI引导的环形HIFU系统可以消融皮下脂肪附近的目标组织，而不会燃烧脂肪。