Comparison of the effects of hydralazine on tumor and normal tissue blood perfusion by MRI.

Abstract

The differential effects on blood perfusion of the vasodilator hydralazine (HYD) between tumor and normal muscle have been measured using the dynamic enhanced-magnetic resonance imaging (DE-MRI) technique. DE-MRI is a noninvasive method of determining blood perfusion in tumors and normal tissues using the MR contrast agent Gd-DTPA. Hydralazine is currently being used in an attempt to increase tumor response to bioreductive agents and to hyperthermia. We show that a dose of 1.2 mg/kg HYD causes an increase in tumor perfusion while doses > or = 2.5 mg/kg cause a decrease in tumor perfusion. The latter was accompanied by a dose-dependent increase in normal muscle perfusion consistent with the "steal effect." This study demonstrates the sensitivity of the DE-MRI technique and its capability of providing estimates of blood perfusion in normal and tumor tissue as well as in smaller regions of a solid tumor. Such features would make it clinically useful in the study of tumor response to radiation therapy and chemotherapy in patients.