Nowadays, both thermal and mechanical ablation techniques of HIFU associated with cavitation have been developed for noninvasive treatment. A specific challenge for the successful clinical implementation of HIFU is to achieve real-time imaging for the evaluation and determination of therapy outcomes such as necrosis or homogenization. Ultrasound Nakagami-m parametric imaging highlights the degrading shadowing effects of bubbles and can be used for tissue characterization. The aim of this study is to investigate the performance of Nakagami-m parametric imaging for evaluating and differentiating thermal coagulation and cavitation erosion induced by HIFU. Lesions were induced in basic bovine serum albumin (BSA) phantoms and ex vivo porcine livers using a 1.6MHz single-element transducer. Thermal and mechanical lesions induced by two types of HIFU sequences respectively were evaluated using Nakagami-m parametric imaging and ultrasound B-mode imaging. The lesion sizes estimated using Nakagami-m parametric imaging technique were all closer to the actual sizes than those of B-mode imaging. The p-value obtained from the t-test between the mean m values of thermal coagulation and cavitation erosion was smaller than 0.05, demonstrating that the m values of thermal lesions were significantly different from that of mechanical lesions, which was confirmed by ex vivo experiments and histologic examination showed that different changes result from HIFU exposure, one of tissue dehydration resulting from the thermal effect, and the other of tissue homogenate resulting from mechanical effect. This study demonstrated that Nakagami-m parametric imaging is a potential real-time imaging technique for evaluating and differentiating thermal coagulation and cavitation erosion.

如今，已开发出与气蚀有关的HIFU热和机械消融技术用于无创治疗。成功实施HIFU的一个具体挑战是实现实时成像，以评估和确定治疗结果（如坏死或均质化）。超声Nakagami-m参数成像突出显示了气泡逐渐降低的阴影效果，可用于组织表征。这项研究的目的是研究Nakagami-m参数成像在评估和区分HIFU引起的热凝结和空化侵蚀方面的性能。在基本牛血清白蛋白（BSA）体模中和离体诱导病变猪肝脏使用1.6MHz单元素换能器。使用Nakagami-m参数成像和超声B型成像分别评估了两种HIFU序列引起的热损伤和机械损伤。与B模式成像相比，使用Nakagami-m参数成像技术估算的病变大小均更接近实际大小。从热凝和空化侵蚀的平均m值之间的t检验得出的p值小于0.05，表明热损伤的m值与机械损伤的m值显着不同，这已通过离体实验得到证实实验和组织学检查表明，HIFU暴露会导致不同的变化，一种是由于热作用引起的组织脱水，另一种是由于机械作用引起的组织匀浆。这项研究表明，Nakagami-m参数成像是一种潜在的实时成像技术，可用于评估和区分热凝结和空化侵蚀。