Nakasone Yutaka, Ikeda Osamu, Kawanaka Koichi, Yokoyama Koichi, Yamashita Yasuyuki
Department of Diagnostic Radiology, Kumamoto University Graduate School of Medical and Pharmaceutical Sciences, Honjo Kumamoto, Japan.
Acta Radiol. 2012 Oct 1;53(8):852-6. doi: 10.1258/ar.2012.110530. Epub 2012 Sep 7.
Radiofrequency ablation (RFA) is susceptible to the cooling effect of flowing blood. The reduced efficacy of RFA in large tumors reflects the in vivo biophysiological limitations imposed by perfusion-mediated vascular cooling.
To compare the effects of RFA alone and of RFA combined with occlusion of the arterial blood supply on the tissue temperature, coagulation diameter, and histological changes in the acute phase.
The temperature at roll-off, the coagulated tissue diameter, and histologic tissue changes were compared in normal porcine kidneys subjected in situ to two pigs each were subjected to RFA alone (four kidneys) or to RFA plus balloon occlusion of the renal artery (four kidneys). The tissue temperature was measured at three sites: area I, the center of the RFA field; area II, the ischemic field 1 cm distant from the edge of the RFA field; and area III, the normal kidney. Tissue samples were stained with hematoxylin and eosin (H&E). Cell viability in the ablated zone was determined by nicotinamide adenine dinucleotide (NADH) staining of frozen sections.
The tissue temperatures achieved by RFA in areas I, II, and III were 101°C, 58°C, and 40°C with and 92°C, 44°C, and 38°C without balloon occlusion, respectively. The maximal coagulation diameter was 31 mm with and 23 mm without occlusion. The coagulation diameter was significantly larger and the temperature in area II was significantly higher in kidneys subjected to RFA with renal artery occlusion. H&E staining showed preservation of the normal renal parenchymal structure outside the thermal lesion and an increase in eosinophilic cells with indistinct cell borders and nuclei within the thermal lesion. H&E and NADH staining demonstrated a sharp demarcation between the ablation and normal tissue area and showed that in area II the addition of balloon occlusion did not produce histologic changes different from those in kidneys subjected to RFA alone.
A technique that combines RFA and partial renal artery occlusion may be useful in treatment of the non-resectable renal tumors with sizes appropriate for RF ablation.
射频消融（RFA）易受血流冷却效应的影响。RFA在大肿瘤中的疗效降低反映了灌注介导的血管冷却所带来的体内生物生理限制。
比较单纯RFA以及RFA联合动脉血供阻断对急性期组织温度、凝固直径和组织学变化的影响。
对正常猪肾进行原位实验，比较脱靶温度、凝固组织直径和组织学变化。每组两只猪，分别接受单纯RFA（四个肾脏）或RFA加肾动脉球囊阻断（四个肾脏）。在三个部位测量组织温度：区域I，RFA区域中心；区域II，距RFA区域边缘1 cm的缺血区域；区域III，正常肾脏。组织样本用苏木精和伊红（H&E）染色。通过对冰冻切片进行烟酰胺腺嘌呤二核苷酸（NADH）染色来确定消融区内的细胞活力。
在有和没有球囊阻断的情况下，RFA在区域I、II和III所达到的组织温度分别为101°C、58°C和40°C以及92°C、44°C和38°C。最大凝固直径在有阻断时为31 mm，无阻断时为23 mm。肾动脉阻断的肾脏凝固直径明显更大，区域II的温度明显更高。H&E染色显示热损伤外正常肾实质结构保存，热损伤内嗜酸性细胞增多，细胞边界和细胞核不清晰。H&E和NADH染色显示消融区与正常组织区域之间有明显界限，且显示在区域II，加用球囊阻断并未产生与单纯接受RFA的肾脏不同的组织学变化。
将RFA与部分肾动脉阻断相结合的技术可能有助于治疗大小适合射频消融的不可切除肾肿瘤。
