1. A method for producing a magnetic resonance image (MRI) of a hemodynamic parameter in tissues, the steps comprising: a) performing a contrast-enhanced magnetic resonance study of the tissues in which a series of MRI images are acquired as a contrast agent flows through the tissues; b) forming a time course NMR image data set with the acquired MRI images, the time course NMR image data set providing a plurality of time course voxel studies which indicate the magnitude of NMR signals produced during the study at voxels throughout the tissues; automatically producing an, arterial input function (AIF) by selecting one of the time course voxel studies based on an analysis of the NMR signals produced during the study; d) calculating a hemodynamic parameter for each voxel using the corresponding time course voxel study and the AIF produced in step c); and e) producing an image in which the brightness of pixels therein is modulated by the hemodynamic parameters calculated in step d).