Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA.
Department of Radiation Oncology, Washington University in St. Louis, St. Louis, Missouri, USA.
Int J Hyperthermia. 2020;37(1):1159-1173. doi: 10.1080/02656736.2020.1825836.
To characterize temperature fields and tissue damage profiles of large-volume hyperthermia (HT) induced by magnetic resonance-guided high-intensity focused ultrasound (MRgHIFU) in deep and superficial targets in a porcine model.
Nineteen HT sessions were performed with a commercial MRgHIFU system (Sonalleve V2, Profound Medical Inc., Mississauga, ON, Canada) in hind leg muscles of eight pigs with temperature fields of cross-sectional diameter of 58-mm. Temperature statistics evaluated in the target region-of-interest (tROI) included accuracy, temporal variation, and uniformity. The impact of the number and location of imaging planes for feedback-based temperature control were investigated. Temperature fields were characterized by time-in-range (TIR, the duration each voxel stays within 40-45 °C) maps. Tissue damage was characterized by contrast-enhanced MRI, and macroscopic and histopathological analysis. The performance of the Sonalleve system was benchmarked against a commercial phantom.
Across all HT sessions, the mean difference between the average temperature (T) and the desired temperature was -0.4 ± 0.5 °C; the standard deviation of temperature 1.2 ± 0.2 °C; the temporal variation of T for 30-min HT was 0.6 ± 0.2 °C, and the temperature uniformity was 1.5 ± 0.2 °C. A difference of 2.2-cm (in pig) and 1.5-cm (in phantom) in TIR dimensions was observed when applying feedback-based plane(s) at different locations. Histopathology showed 62.5% of examined HT sessions presenting myofiber degeneration/necrosis within the target volume.
Large-volume MRgHIFU-mediated HT was successfully implemented and characterized in a porcine model in deep and superficial targets with heating distributions modifiable by user-definable parameters.
在猪模型中，对磁共振引导高强度聚焦超声（MRgHIFU）诱导的大容量热疗（HT）的温度场和组织损伤分布进行特征描述，该 HT 作用于深部和表浅靶区。
使用商业性的磁共振引导高强度聚焦超声系统（Sonalleve V2，Profound Medical Inc.，安大略省密西沙加市），在 8 头猪的后腿肌肉中进行了 19 次 HT 治疗，其横截面直径为 58mm。在靶区感兴趣区（tROI）中对温度进行了统计评估，包括准确性、时间变化和均匀性。研究了基于反馈的温度控制中成像平面的数量和位置对温度场的影响。采用时间-范围（TIR，每个体素处于 40-45°C 之间的持续时间）图来描述温度场。采用对比增强 MRI 及宏观和组织病理学分析来描述组织损伤。对 Sonalleve 系统的性能与商业性体模进行了基准测试。
在所有 HT 治疗中，平均温度（T）与目标温度之间的平均差值为-0.4±0.5°C；温度标准差为 1.2±0.2°C；30 分钟 HT 的 T 时间变化为 0.6±0.2°C，温度均匀性为 1.5±0.2°C。当在不同位置应用基于反馈的平面时，TIR 尺寸的差异在猪中为 2.2cm，在体模中为 1.5cm。组织病理学显示，在 62.5%的检查 HT 治疗中，目标体积内存在肌纤维变性/坏死。
在深部和表浅靶区，使用可用户定义参数调节加热分布的磁共振引导高强度聚焦超声系统，成功地在猪模型中实现并描述了大容量的 HT。
