Laugier P, Laplace E, Lefaix J L, Berger G
Laboratoire d'Imagerie Paramétrique, URA CNRS, Paris, France.
J Invest Dermatol. 1998 Aug;111(2):314-9. doi: 10.1046/j.1523-1747.1998.00288.x.
One of the main difficulties encountered in cryosurgery is the uncertainty in the extent and depth of the tissue effectively treated during the freezing process. The objective of this study was to evaluate in vivo ultrasonic control of skin cryosurgery using a new echographic cryoprobe. An echographic cryoprobe, developed specifically for dermatology applications, combines a high-frequency (20 MHz) miniature ultrasonic transducer and a N2O-driven closed cryoprobe. Knowledge of the ultrasound velocity of frozen skin is a prerequisite for monitoring the iceball formation kinetics. Therefore, in a first study, we estimated the ultrasound velocity of frozen skin specimens. In a second step, the operation of the echographic cryoprobe was assessed, under in vivo conditions similar to those used in human therapeutics, on normal skin of three female "Large-White" pigs under anesthesia. The mean value of ultrasound velocity of frozen skin obtained by pooling the data from all the skin specimens included in this study was 2865 +/- 170 m per s. The average rates of growth (10(-2) mm per s) of the iceballs were found to be 12.2 +/- 1.0 (pig 1), 9.0 +/- 1.0 (pig 2), and 8.4 +/- 0.9 (pig 3). The echographic cryoprobe had a built-in high-frequency ultrasonic transducer that served two functions. It enabled in vivo real-time monitoring of depth penetration of the iceball and it gave important feedback to the operator or to the console relating to the rate of growth of the iceball. Automatic (i.e., operator-independent) detection of the echo signal from the freezing front and calculation of the depth penetration of the iceball was possible.
冷冻手术中遇到的主要困难之一是在冷冻过程中有效治疗的组织范围和深度存在不确定性。本研究的目的是使用一种新型超声冷冻探头评估皮肤冷冻手术的体内超声控制。一种专门为皮肤科应用开发的超声冷冻探头，结合了高频（20 MHz）微型超声换能器和N2O驱动的封闭式冷冻探头。了解冷冻皮肤的超声速度是监测冰球形成动力学的先决条件。因此，在第一项研究中，我们估计了冷冻皮肤标本的超声速度。第二步，在与人类治疗中使用的条件相似的体内条件下，对三只麻醉下的雌性“大白”猪的正常皮肤评估超声冷冻探头的操作。通过汇总本研究中所有皮肤标本的数据获得的冷冻皮肤超声速度平均值为2865 +/- 170米/秒。发现冰球的平均生长速率（10^(-2)毫米/秒）分别为12.2 +/- 1.0（猪1）、9.0 +/- 1.0（猪2）和8.4 +/- 0.9（猪3）。超声冷冻探头有一个内置的高频超声换能器，它有两个功能。它能够在体内实时监测冰球的深度穿透情况，并就冰球的生长速率向操作员或控制台提供重要反馈。可以自动（即独立于操作员）检测来自冷冻前沿的回波信号并计算冰球的深度穿透情况。
