Department of Vascular & Interventional Radiology, Interventional Radiology Center, Johns Hopkins University, Sheikh Zayed Tower, Suite 7203, 1800 Orleans Street, Baltimore, MD 21287, USA.
Cardiovasc Intervent Radiol. 2013 Jun;36(3):783-90. doi: 10.1007/s00270-012-0470-5. Epub 2012 Aug 30.
The study was designed to determine the distance between the visible "ice-ball" and the lethal temperature isotherm for normal renal tissue during cryoablation.
The Animal Care Committee approved the study. Nine adult swine were used: three to determine the optimum tissue stain and six to test the hypotheses. They were anesthetized and the left renal artery was catheterized under fluoroscopy. Under MR guidance, the kidney was ablated and (at end of a complete ablation) the nonfrozen renal tissue (surrounding the "ice-ball") was stained via renal artery catheter. Kidneys were explanted and sent for slide preparation and examination. From each slide, we measured the maximum, minimum, and an in-between distance from the stained to the lethal tissue boundaries (margin). We examined each slide for evidence of "heat pump" effect.
A total of 126 measurements of the margin (visible "ice-ball"-lethal margin) were made. These measurements were obtained from 29 slides prepared from the 6 test animals. Mean width was 0.75 ± 0.44 mm (maximum 1.15 ± 0.51 mm). It was found to increase adjacent to large blood vessels. No "heat pump" effect was noted within the lethal zone. Data are limited to normal swine renal tissue.
Considering the effects of the "heat pump" phenomenon for normal renal tissue, the margin was measured to be 1.15 ± 0.51 mm. To approximate the efficacy of the "gold standard" (partial nephrectomy, ~98 %), a minimum margin of 3 mm is recommended (3 × SD). Given these assumptions and extrapolating for renal cancer, which reportedly is more cryoresistant with a lethal temperature of -40 °C, the recommended margin is 6 mm.
本研究旨在确定冷冻消融过程中正常肾组织的可见“冰球”与致死温度等温线之间的距离。
动物护理委员会批准了这项研究。使用了 9 头成年猪：3 只为了确定最佳组织染色，6 只为了验证假设。它们在麻醉下接受了左肾动脉导管插入术，并在透视引导下进行了肾脏消融，在完全消融结束时，通过肾动脉导管对未冻结的肾组织（环绕“冰球”）进行染色。肾脏被取出并用于幻灯片制备和检查。从每张幻灯片上，我们测量了染色到致死组织边界（边缘）的最大、最小和中间距离。我们检查了每张幻灯片，以确定是否存在“热泵”效应。
共对 6 只测试动物的 29 张幻灯片进行了 126 次边缘（可见“冰球”-致死边缘）测量。平均宽度为 0.75 ± 0.44 毫米（最大宽度为 1.15 ± 0.51 毫米）。发现它在靠近大血管的地方会增加。在致死区内未发现“热泵”效应。数据仅限于正常猪肾组织。
考虑到正常肾组织“热泵”现象的影响，边缘测量值为 1.15 ± 0.51 毫米。为了近似“金标准”（部分肾切除术，约 98%）的疗效，建议最小边缘为 3 毫米（3×SD）。基于这些假设和对冷冻治疗更耐受、致死温度为-40°C 的肾肿瘤的推断，建议的边缘为 6 毫米。
