Characteristic values of MR examinations of cerebral perfusion with high spatial and temporal resolution

Purpose: Different parameters for the evaluation of perfusion studies with dynamic MR-measurements after the administration of paramagnetic contrast agent were compared. Method: An echo planar imaging (EPI) sequence was developed that allows dynamic multi-slice data acquisition. Evaluations of the measurements were performed by calculating parameter maps. Phenomenological quantities such as maximal signal reduction and time to peak as well as derived quantities such as approximations of the regional cerebral blood volume were used as parameters. Patients with a low grade astrocytoma, with an acute cerebral infarction and with stenoses of the carotid arteries were examined. Results: On comparison of the derived parameters with the phenomenological parameters no major differences were found in qualitative comparisons of the parameter maps. The comparison of relative parameter values in selected regions within the datasets of 20 patients show a high correspondence between phenomenological and derived parameter values. Conclusions: Using EPI measurement techniques with high temporal resolution, parameter maps of simple values like maximal signal reduction and time-to-peak are sufficient to visualize relative differences of perfusion within the selected slices. However, the calculation of relative rCBV and rCBF values might be helpful for the detailed characterization of signal courses in selected regions.