Langevin Institute (CNRS UMR 7587), INSERM ERL U979, ESPCI ParisTech, 10 rue Vauquelin, 75 005 Paris, France.
Phys Med Biol. 2010 Mar 21;55(6):1701-18. doi: 10.1088/0031-9155/55/6/011. Epub 2010 Mar 2.
Soft tissue stiffness was shown to significantly change after thermal ablation. To better understand this phenomenon, the study aims (1) to quantify and explain the temperature dependence of soft tissue stiffness for different organs, (2) to investigate the potential relationship between stiffness changes and thermal dose and (3) to study the reversibility or irreversibility of stiffness changes. Ex vivo bovine liver and muscle samples (N = 3 and N = 20, respectively) were slowly heated and cooled down into a thermally controlled saline bath. Temperatures were assessed by thermocouples. Sample stiffness (shear modulus) was provided by the quantitative supersonic shear imaging technique. Changes in liver stiffness are observed only after 45 degrees C. In contrast, between 25 degrees C and 65 degrees C, muscle stiffness varies in four successive steps that are consistent with the thermally induced proteins denaturation reported in the literature. After a 6 h long heating and cooling process, the final muscle stiffness can be either smaller or bigger than the initial one, depending on the stiffness at the end of the heating. Another important result is that stiffness changes are linked to thermal dose. Given the high sensitivity of ultrasound to protein denaturation, this study gives promising prospects for the development of ultrasound-guided HIFU systems.
软组织硬度在热消融后会显著改变。为了更好地理解这一现象，本研究旨在：(1) 量化并解释不同器官的软组织硬度对温度的依赖性；(2) 研究硬度变化与热剂量之间的潜在关系；(3) 研究硬度变化的可逆性或不可逆性。离体牛肝和肌肉样本（分别为 N = 3 和 N = 20）在热控盐水中被缓慢加热和冷却。温度由热电偶评估。样本硬度（剪切模量）由定量超声剪切成像技术提供。仅在 45 摄氏度后观察到肝硬度的变化。相比之下，在 25 摄氏度至 65 摄氏度之间，肌肉硬度经历了四个连续的阶段，这与文献中报道的热诱导蛋白质变性一致。经过 6 小时的加热和冷却过程，最终的肌肉硬度可能比初始硬度小或大，具体取决于加热结束时的硬度。另一个重要的结果是，硬度变化与热剂量有关。鉴于超声对蛋白质变性的高度敏感性，本研究为开发超声引导的高强度聚焦超声系统提供了有前景的前景。
