Biophysical models on multi-parametric maps reveal brain tissue changes in molecular environments of iron and myelin in multiple sclerosis at 3T

Motivation: Quantitative MRI is attractive for investigating pathological tissue changes, yet translation towards clinical research remains challenging. Goal(s): Our goal was to explore sensitivity of a fast quantitative multi-parametric mapping protocol combined with biophysical models at 3T to multiple sclerosis subtypes. Approach: We combined quantitative maps of magnetization transfer saturation, proton density, longitudinal and transverse relaxation rates with relaxivity approaches to disentangle water and macromolecular tissue driven changes and to identify MRI biomarkers of focal and diffuse demyelination or inflammation. Results: We found significant alterations in white matter and lesions of surrogates for myelin and iron compared to controls and worsening with disease severity. Impact: A fast quantitative multi-parameter mapping protocol combined with biophysical models based on in vivo relaxivity approaches in multiple sclerosis at 3T is sensitive to brain tissue alterations in patients, suggesting disease-specific demyelination and inflammation. An association with disability suggests disease-relevance.