Effects of Vascular Perfusion on Coagulation Size in Radiofrequency Ablation of Ex Vivo Perfused Bovine Livers

Abstract

The model reproduced the cooling effect of perfused tissue during RFA. The ablation areas produced under perfusion conditions had smaller diameters despite longer exposure times and higher energy deposition.

Ex situ quantification of the cooling effect of liver vessels on radiofrequency ablation

“…The second cooling effect is caused by larger liver vessels that limit both the size and shape of the RF lesion [11]. This local effect is difficult to predict, since it is dependent on the vessel anatomy of the individual patient.…”

Effect of Change in Portal Venous Blood Flow Rates on the Performance of a 2.45-GHz Microwave Ablation Device

“…The consensus from those experiments is that blood vessels larger than 3-4 mm adjacent to or embedded within ablation zones cause substantial local "heat sink effect" on radiofrequency ablation zones but little to no effect on microwave ablation zones created by using either 915-MHz or 2.45-GHz devices (14)(15)(16)(17)(18)(19)(20)(21). Also, temporary occlusion of regional or global hepatic blood flow causes an increase in the overall size of ablation zones created by radiofrequency and microwave ablation devices (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)13,17,22,23). The studies of the change in hepatic blood flow within the normal physiological range have demonstrated as much as a threefold decrease in radiofrequency ablation zone volume as hepatic blood flow reaches upper physiological rates (11,25) but little to no effect of physiological fluctuations in hepatic blood flow on ablation zone volume created by 915-MHz microwave ablation devices (25).…”

Electro-physiological parameters of hepatic radiofrequency ablation—a comparison of an in vitro versus an in vivo porcine liver model

“…About 1.5 kJ/ml is needed to transfer vital tissue into a necrosis without perfusion [13]. It is also described that, under perfusion, much more energy is transferred during RFA and the volume of necrosis is smaller [14,15]. How much energy is really needed under physiological perfusion is not known.…”