A magnetic resonance imaging (MRI) system and method (a) acquires k-space data for a patient ROI over a predetermined band of RF frequencies using RF excitation pulses having respectively corresponding RF frequencies incrementally offset from a nuclear magnetic resonant (NMR) Larmor frequency for free nuclei over a predetermined range of different offset frequencies in which target macromolecule responses are expected and to process such acquired data into spectral data for voxels in the ROI; (b) analyzes the acquired spectral data to provide spectral peak width data corresponding to tissue values in the ROI for macromolecules participating in magnetization transfer contrast (MTC) effects producing said spectral data; and (c) stores and/or displays data representative of tissue values of the ROI which values are different for different tissues.