MRI can provide multiple images of the same anatomy, each with different contrast characteristics.
Contrast is controlled by selection of imaging pulse sequence parameters.
Analysis of multi-spectral MR data is one of the most exciting and promising areas of medical image processing. Analysis of multi-spectral images may provide much more information than analysis of a single contrast image. I am currently using multi-spectral techniques to analyse images of patients with Multiple Sclerosis, and to determine the composition of atherosclerotic plaques in carotid artery specimens.