Large blood vessel cooling in heated tissues: a numerical study

Area of Science:

• Biomedical Engineering
• Thermal Medicine
• Computational Fluid Dynamics

Background:

• Large blood vessels create steep temperature gradients, hindering effective tissue heating during hyperthermia treatments.
• Accurate modeling of heat transfer in vascularized tissues is crucial for optimizing thermal therapies.

Purpose of the Study:

• To model blood vessel cooling effects on tissue temperature during hyperthermia using a finite difference scheme.
• To investigate the influence of microvascular heat transfer models and perfusion on thermal profiles near large vessels.

Main Methods:

• Utilized a finite difference scheme to solve coupled heat transfer and fluid flow equations, implicitly modeling heat exchange with large blood vessels.
• Modeled microvascular heat transfer using either an effective conductivity or a heat sink approach.
• Calculated tissue temperature profiles near thermally significant vessels under various perfusion conditions.

Main Results:

• Increased microvascular perfusion reduced the cooling effect of large blood vessels.
• The effective conductivity model predicted more efficient heating of blood and adjacent tissues compared to the heat sink model for equivalent perfusion.
• Optimal hyperthermia strategies are dependent on the microvascular model used; localized heating near vessels was more effective with the bioheat transfer equation (BHTE) than the effective thermal conductivity equation (ETCE).

Conclusions:

• Reducing blood flow in large vessels is the most effective method to mitigate localized cooling and improve hyperthermia efficacy.
• The choice of microvascular heat transfer model significantly impacts the prediction of heating effectiveness and optimal treatment strategies.