Quantitative MRI maps are believed to strongly correlate with myelin and and ferritin content. Recently, a model combining prior information from non-MRI quantitative techniques was proposed for the quantification of myelin and ferritin based on relaxometry information $$$R_1$$$ and $$$R_2^*$$$ in post mortem human brain samples. Here, we propose four different simple linear models for tentatively obtaining semi-quantitative information using simultaneous quantitative acquisitions under in vivo conditions. Three of the four model are relatively consistent, but do not agree with previously published measurements. A fourth model, although not validated, is compatible with previous works.