Sheng Lei, Wang Gubing, Li Fubing, Luo Jianwen, Liu Jing
Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084, China.
Department of Biomedical Engineering, Imperial College London, London, United Kingdom.
Cryobiology. 2014 Feb;68(1):29-34. doi: 10.1016/j.cryobiol.2013.11.003. Epub 2013 Nov 20.
Cryosurgery has a number of advantages that make it particularly appealing in the treatment of liver cancer. However, a major problem for the wide clinical adoption of hepatic cryosurgery is the lack of a cost effective high resolution imaging way which is capable of both performing precise monitoring of the freezing process in situ and evaluating the postoperative effects after surgery. The mean scatterer spacing has been found to be an important parameter for describing the ultrasonic scattering and characterization of biological tissues. However, its potential values in the evaluation of cryosurgical effects of tissues reserved unclear so far. Here, we investigated the wavelet analysis to estimate the mean scatterer spacing parameter in normal and freeze-thawed tissues on porcine livers in vitro. The experimental results carried out at 10 MHz using weakly focused pulse-echo signal element transducer indicated that the mean scatterer spacing in normal liver tissues is 1.12 ± 0.13 mm whereas it is 1.67 ± 0.25 mm in several pre-frozen and then thawed tissues. These results disclosed the good correlation between the wavelet data and microstructures of the normal or thawed tissues, and hence demonstrated that the wavelet analysis holds promise to be used as an effective method for the characterization of thawed tissues scatterer spacing. The present method offers a potential pragmatic strategy for monitoring the transition zone between frozen and unfrozen tissues during the surgical therapy, and evaluating postoperative effects.
冷冻手术具有诸多优势，使其在肝癌治疗中极具吸引力。然而，肝脏冷冻手术在临床上广泛应用的一个主要问题是缺乏一种经济高效的高分辨率成像方法，该方法既要能够对原位冷冻过程进行精确监测，又要能评估术后效果。平均散射体间距已被发现是描述生物组织超声散射和特征的一个重要参数。然而，其在评估组织冷冻手术效果方面的潜在价值迄今仍不明确。在此，我们研究了小波分析，以估计体外猪肝脏正常组织和冻融组织中的平均散射体间距参数。使用弱聚焦脉冲回波信号单元换能器在10MHz下进行的实验结果表明，正常肝脏组织中的平均散射体间距为1.12±0.13mm，而在几个预冷冻然后解冻的组织中为1.67±0.25mm。这些结果揭示了小波数据与正常或解冻组织微观结构之间的良好相关性，因此表明小波分析有望用作表征解冻组织散射体间距的有效方法。本方法为手术治疗期间监测冷冻组织和未冷冻组织之间的过渡区以及评估术后效果提供了一种潜在的实用策略。
