Mechanical fractionation of tissues using microsecond-long HIFU pulses on a clinical MR-HIFU system
Mechanical fractionation of tissues using microsecond-long HIFU pulses on a clinical MR-HIFU system
复制标题
DOI：
10.1080/02656736.2018.1438672
复制
发表时间：
2018-01-01
影响因子：
3.1
通讯作者：
Wood, Bradford J.
中科院分区：
文献类型：
--
作者：
Eranki, Avinash;Farr, Navid;Wood, Bradford J.
目的：高强度聚焦超声（HIFU）可以无创治疗肿瘤，对中间组织的损伤最小或无损伤。当连续波HIFU热消融靶组织时，本研究检查了数百微秒长的脉冲超声的效果。本研究的目的是表征超声参数相关的热机械生物效应，为未来的临床前研究和促进临床转化提供基础。方法和材料：在临床磁共振成像（MRI）引导下的HIFU （MR-HIFU）系统上改变声功率、周期/脉冲数、超声时间和脉冲重复频率（PRF）。对离体猪肝脏、肾脏和心肌组织进行超声扫描（3x3网格，间隔1mm）。MRI定量测量温度、热剂量和T2弛豫时间。用H&E和波形蛋白染色对病变进行组织学分析，观察病变的结构和活力。结果：热机械性HIFU生物效应产生不同类型的组织病变：固体/热、糊状和空泡状。在20或60Hz PRF下，超声在病灶区域以外产生大量组织损伤，在波形蛋白染色上活性降低，而H&E染色显示组织完整。相同的超声参数在不同的组织类型中产生不同的病变，参数组之间的温度、热剂量和T2存在显著差异。结论：临床MR-HIFU系统可以在离体组织中产生不同类型的病变，并产生有针对性的热力学生物效应。结果指导HIFU热机械组织生物效应的研究，为未来的研究提供信息，并建议使用临床MR-HIFU系统直接肿瘤消融或免疫调节的超声参数选择。
Purpose: High intensity focussed ultrasound (HIFU) can non-invasively treat tumours with minimal or no damage to intervening tissues. While continuous-wave HIFU thermally ablates target tissue, the effect of hundreds of microsecond-long pulsed sonications is examined in this work. The objective of this study was to characterise sonication parameter-dependent thermomechanical bioeffects to provide the foundation for future preclinical studies and facilitate clinical translation.Methods and materials: Acoustic power, number of cycles/pulse, sonication time and pulse repetition frequency (PRF) were varied on a clinical magnetic resonance imaging (MRI)-guided HIFU (MR-HIFU) system. Ex vivo porcine liver, kidney and cardiac muscle tissue samples were sonicated (3x3 grid pattern, 1mm spacing). Temperature, thermal dose and T2 relaxation times were quantified using MRI. Lesions were histologically analysed using H&E and vimentin stains for lesion structure and viability.Results: Thermomechanical HIFU bioeffects produced distinct types of fractionated tissue lesions: solid/thermal, paste-like and vacuolated. Sonications at 20 or 60Hz PRF generated substantial tissue damage beyond the focal region, with reduced viability on vimentin staining, whereas H&E staining indicated intact tissue. Same sonication parameters produced dissimilar lesions in different tissue types, while significant differences in temperature, thermal dose and T2 were observed between the parameter sets.Conclusion: Clinical MR-HIFU system was utilised to generate distinct types of lesions and to produce targeted thermomechanical bioeffects in ex vivo tissues. The results guide HIFU research on thermomechanical tissue bioeffects, inform future studies and advice sonication parameter selection for direct tumour ablation or immunomodulation using a clinical MR-HIFU system.