Understanding human brain structure and function organization in health, disease and development is one of the great challenges for neuroscience. Magnetic resonance imaging (MRI) is the most valuable technique for noninvasive in vivo imaging of human brain. However, the use of MRI is currently limited, due to the lack of theory that links the specific biological structures to the measured signal. In my presentation I will describe a new quantitative MRI (qMRI) method that directly measures two biophysical properties of the human brain tissue: the macromolecular tissue volume and the macromolecular physico-chemical environment. I will discuss how such quantities can be used for 1) individualize diagnostic applications and 2) mapping structure-function relations in cognitive processes such as reading.