3D numerical reconstruction of the hyperthermia induced temperature distribution in human sarcomas using DE-MRI measured tissue perfusion: validation against non-invasive MR temperature measurements.

Essential to the success of optimized thermal treatment during hyperthermia is accurate modelling. Advection of energy due to blood perfusion significantly affects the temperature. Without accurate estimates of the magnitude of the local tissue blood perfusion, accurate estimates of the temperature distribution can not be made. It is shown here that the blood mass flow rate per unit volume of tissue in the Pennes' bio-heat equation can be modelled using a relative perfusion index (RPI) determined with dynamic-enhanced magnetic resonance imaging (DE-MRI). Temperature distributions in two patients treated with hyperthermia at Duke University Medical Center for high-grade leg tissue sarcomas are modelled, and the resultant temperatures are compared to measured temperatures using a non-invasive MR thermometry technique. Significant correlations are found between the DE-MRI perfusion images, the MR temperature images, and the numerical simulation of the temperature field. The correlation between DE-MRI measured values and advective heat loss in tissue is used to scale the perfusion distribution, thereby allowing the continuum model to account for the local thermal impact of vasculature in the tumour. Large vessels in tumour and neighbouring healthy tissue need to be taken into account in order to accurately describe the complete temperature distribution.