Consiglieri Luisa, dos Santos Icaro, Haemmerich Dieter
Department of Mathematics and CMAF, University of Lisboa, Av Prof Gama Pinto 2, 1649-003 Lisboa, Portugal.
Phys Med Biol. 2003 Dec 21;48(24):4125-34. doi: 10.1088/0031-9155/48/24/010.
Ablative therapies such as radio-frequency (RF) ablation are increasingly used for treatment of tumours in liver and other organs. Often large vessels limit the extent of the thermal lesion, and cancer cells close to the vessel survive resulting in local tumour recurrence. Accurate estimates of the heat convection coefficient h for large vessels will help improve ablation techniques, and are required for estimation of thermal lesion dimensions in simulations. Previous estimates of h did not consider that only part of the vessel is heated, and assumed uniform temperature distribution at the vessel wall. An analytical relationship between the heat convection coefficient, blood velocity and temperature is formulated. The heat convection coefficient evaluated will assist both simulations and design of proper protocols for in vivo measurements. The mathematical model developed in this work describes the exchange of heat between a solid surface and a moving fluid and it is based on energy and motion equations for Navier-Stokes fluids. A particular case of a laminar blood flow in the portal vein is studied when a portion of its surface is heated. The results show that heating a larger portion of the vessels reduces convective heat loss, which may result in more effective ablation strategies.
诸如射频（RF）消融之类的消融疗法越来越多地用于治疗肝脏和其他器官中的肿瘤。大血管常常会限制热损伤的范围，靠近血管的癌细胞得以存活，从而导致局部肿瘤复发。准确估算大血管的热对流系数h将有助于改进消融技术，并且在模拟中估算热损伤尺寸时也是必需的。先前对h的估算没有考虑到只有部分血管被加热，并且假定血管壁温度分布均匀。本文推导了热对流系数、血流速度和温度之间的解析关系。所评估出的热对流系数将有助于模拟以及设计合适的体内测量方案。本研究建立的数学模型描述了固体表面与流动流体之间的热交换，它基于纳维-斯托克斯流体的能量和运动方程。研究了门静脉中部分表面被加热时层流血流的一种特殊情况。结果表明，加热更大比例的血管会减少对流热损失，这可能会产生更有效的消融策略。
