Ahmed Muneeb, Liu Zhengjun, Afzal Karim S, Weeks Dawn, Lobo S Melvyn, Kruskal Jonathan B, Lenkinski Robert E, Goldberg S Nahum
Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215, USA.
Radiology. 2004 Mar;230(3):761-7. doi: 10.1148/radiol.2303021801.
To determine the effect of surrounding tissue type on coagulation necrosis from radiofrequency (RF) ablation in a homogeneous animal tumor model.
Thirty canine venereal sarcomas were implanted in three tissue sites (subcutaneous, kidney, and lung) in 13 mildly immunosuppressed dogs. Five of 25 tumors, which were 19 mm +/- 3 (mean +/- SD) in diameter, were allocated to each of five groups: (a) subcutaneous tumors, (b) kidney tumors, (c) lung tumors with blood flow, and (d) subcutaneous and (e) renal tumors without blood flow, which was achieved by sacrificing the animal to eliminate tumor perfusion. A sixth group comprised larger subcutaneous tumors (mean diameter, 46 mm +/- 4) that were also treated. RF ablation was performed with a 1-cm tip and 5 minutes of ablation at 90 degrees C +/- 1. Impedance, temperature, and resultant coagulation diameter were recorded and compared. Data were analyzed statistically, including one-way analysis of variance to determine the effect of tissue conductivity (ie, systemic impedance) on necrosis size and tissue temperatures. Linear regression analysis was used to compare changes in impedance between the control and experimental groups.
Increasing linear correlation was observed between tumor coagulation diameter and overall baseline system impedance (R(2) = 0.65). RF ablation of lung tumors resulted in the greatest coagulation diameter (13.0 mm +/- 3.5) compared with that in the other groups (P <.01). The smallest coagulation diameter was observed in kidney tumors in the presence of blood flow (7.3 mm +/- 0.6) compared with that in the other groups (P <.01). Elimination of blood flow in kidney tumors increased coagulation diameter to 10.3 mm +/- 0.6 (P <.01). After RF ablation, coagulation diameter in the subcutaneous tumor groups was the same (mean, 9.8 mm +/- 1.0) (difference not significant), regardless of tumor size or presence of blood flow.
The characteristics of tissue that surrounds tumor, including vascularity and electric conductivity, affect ablation outcome. Predominance of tissue-specific characteristics will likely result in site-specific differences in RF-induced coagulation necrosis.
在均质动物肿瘤模型中确定周围组织类型对射频（RF）消融所致凝固性坏死的影响。
在13只轻度免疫抑制的犬体内的三个组织部位（皮下、肾脏和肺）植入30个犬传染性肉瘤。25个直径为19 mm±3（均值±标准差）的肿瘤，每组5个，分为五组：（a）皮下肿瘤，（b）肾脏肿瘤，（c）有血流的肺肿瘤，（d）皮下肿瘤以及（e）无血流的肾脏肿瘤，后者通过处死动物以消除肿瘤灌注来实现。第六组包括也接受治疗的较大皮下肿瘤（平均直径，46 mm±4）。使用1 cm尖端在90℃±1下进行5分钟的射频消融。记录并比较阻抗、温度及由此产生的凝固直径。对数据进行统计学分析，包括单向方差分析以确定组织电导率（即全身阻抗）对坏死大小和组织温度的影响。使用线性回归分析比较对照组和实验组之间的阻抗变化。
观察到肿瘤凝固直径与总体基线系统阻抗之间呈线性相关性增加（R² = 0.65）。与其他组相比，肺肿瘤的射频消融导致最大的凝固直径（13.0 mm±3.5）（P <.01）。与其他组相比，有血流的肾脏肿瘤中观察到最小的凝固直径（7.3 mm±0.6）（P <.01）。消除肾脏肿瘤中的血流可使凝固直径增加至10.3 mm±0.6（P <.01）。射频消融后，皮下肿瘤组的凝固直径相同（均值，9.8 mm±1.0）（差异不显著），无论肿瘤大小或有无血流。
肿瘤周围组织的特征，包括血管分布和电导率，会影响消融结果。组织特异性特征的优势可能导致射频诱导的凝固性坏死存在部位特异性差异。
