Evaluation of tumor blood perfusion by dynamic MRI and CT in patients undergoing thermoradiotherapy

In 18 patients who were treated with combined regional hyperthermia and radiation for recurrent pelvic tumors, blood flow related data were obtained using dynamic computed tomography and dynamic magnetic resonance imaging. The enhancement of contrast material (delta HU) and Gadolinium DTPA (delta SI) over baseline in the early phase (15-30 s) after bolus injection is dependent upon perfusion. With both methods significant differences in global perfusion have been observed between tumor center and tumor periphery. With regard to the mean perfusion values we are able to separate high, medium and low perfused pelvic tumors. Flow rates expressed as delta HU for dynamic CT and delta SI for dynamic MRI show a significant inverse correlation with the achieved steady state temperatures above baseline. Values of enhancement of contrast material higher than 15-35 delta HU or 300-700 delta SI indicate flow rates which were limiting in achieving steady state temperatures higher than 3 degrees C above baseline (core temperature).