The overall effects of intravenous Gd-DTPA on tissue signal in intracranial tumors are complex depending on dose, time of administration, pulse sequence, and tissue structure. Ultrahigh speed EPI permits the kinetics of tissue enhancement in intracranial tumors to be studied during the "wash-in" equilibrium and "wash-out" phases. Ongoing studies employing dynamic scanning have shown it to be a valuable adjunct to a morphological study of tumors, providing an assessment of vascularity which is important in planning resection; and demonstrating areas with maximal breakdown of the blood-brain barrier which are most suitable for stereotactic biopsy. There are grounds for anticipating that the analysis of the temporal profile of enhancement may allow discrimination between different tumor types and provide information on factors which relate to the malignant potential of a single type.