The tissue composition of the brain can be related to different contrast sources in quantitative MRI. Notably, T1 and T2* strongly correlate with myelin and iron. However, other components may play a role in contrast generation. In particular, the hyaluronan component of the extracellular matrix has been recently proposed as a possible important contributor to MRI contrast. Here, we quantify the bulk contribution of hyaluronan to quantitative relaxation maps. This is obtained by characterizing the evolution of the relevant MRI parameters over time during the enzymatic digestion of the hyaluronan.