High-intensity focused ultrasound (HIFU) has demonstrated the capacity to be used for local thermal ablation in clinical surgery; however, relying solely on conventional ultrasound B-mode imaging to monitor HIFU thermal ablation and determine ablation levels remains a challenge. Here, we experimentally demonstrate the ability to use Nakagami imaging to monitor HIFU-induced thermal lesions in porcine livers ex vivo. Ultrasonic Nakagami imaging has been proven to be able to characterize tissues with different scatterer concentrations and distributions. The pathological sections from HIFU thermally ablated porcine liver tissues reveal that normal and denatured tissues significantly differ in scatterer concentration and distribution. Therefore, we believe that Nakagami imaging can be used to monitor thermal ablation by tracing Nakagami parameter changes in liver tissues. The ex vivo porcine liver experiments were performed using a homemade HIFU device synchronized with a commercial diagnostic ultrasound scanner to obtain the ultrasound envelope data before and after thermal ablation. These data were used to evaluate the performance of thermal lesion characterization using Nakagami imaging and were compared with those derived from conventional B-mode imaging. Experimental results showed that Nakagami imaging can be used to identify thermal lesions, which are difficult to visualize using conventional B-mode imaging because there is no apparent bubble formation. In cases with apparent bubble formation, Nakagami imaging could provide a more accurate estimation of lesion size and position. In addition, the Nakagami imaging algorithm is characterized by low computational complexity, which means it can be easily integrated as postprocessing for existing array imaging systems.

中文翻译：

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高强度聚焦超声引起的猪肝脏热损伤的超声 Nakagami 成像：离体研究

高强度聚焦超声 (HIFU) 已证明可用于临床手术中的局部热消融；然而，仅仅依靠传统的超声 B 模式成像来监测 HIFU 热消融和确定消融水平仍然是一个挑战。在这里，我们通过实验证明了使用 Nakagami 成像来监测离体猪肝脏中 HIFU 诱导的热损伤的能力。超声 Nakagami 成像已被证明能够表征具有不同散射体浓度和分布的组织。HIFU 热消融猪肝组织的病理切片显示，正常和变性组织在散射体浓度和分布方面存在显着差异。所以，我们相信 Nakagami 成像可以通过跟踪肝组织中的 Nakagami 参数变化来监测热消融。离体猪肝实验是使用自制的 HIFU 设备与商业诊断超声扫描仪同步进行的, 以获得热消融前后的超声包络数据。这些数据用于评估使用 Nakagami 成像的热损伤表征的性能，并与来自传统 B 模式成像的数据进行比较。实验结果表明，Nakagami 成像可用于识别热损伤，因为没有明显的气泡形成，因此使用常规 B 模式成像难以可视化。在有明显气泡形成的情况下，Nakagami 成像可以更准确地估计病变大小和位置。