Determination of changes in tumor blood perfusion after hydralazine treatment by dynamic paramagnetic-enhanced magnetic resonance imaging

Magnetic resonance imaging, using the paramagnetic chelate gadopentetate dimeglumine as a perfusing agent, was used to investigate the effect of the vasoactive drug hydralazine on tumor blood perfusion. The method requires measurements of the magnetic resonance image intensity changes with time on a pre-selected region of interest in the tumor image, immediately following intravenous injection of gadopentetate dimeglumine. The present study showed that the initial slope of the intensity-time curve can be used, to a first approximation, to infer tumor blood perfusion. With the dynamic imaging technique, it was demonstrated that, in the KHT sarcoma implanted intramuscularly in the hind leg of C3H/HeN mice, intraperitoneal administration of hydralazine reduced the volume-averaged tumor blood perfusion in a dose-dependent manner. The intrinsically high spatial resolution of magnetic resonance imaging allows a detailed study of the heterogeneous nature of tumor blood perfusion. The potential applications of this imaging technique to study the differential effects of hydralazine on perfusion between tumor and normal tissues will be discussed. The clinical utility of the technique should be promising because of its non-invasive nature.