Quantitative multi-parametric relaxometry MRI (e.g., T1, T2, and T1ρ mapping) can demonstrate longitudinal brain changes and enhance lesion contrasts against normal appearing matters in multiple sclerosis. Conventional methods that quantify these relaxation parameters are time-consuming and subject to motion, thus challenging for clinical practice. We present a novel approach that simultaneously quantifies T1, T2, and T1ρ with whole brain coverage in 9min, using the recently developed Multitasking framework that models the multidimensional image as a low-rank tensor. This technique is validated on healthy volunteers. We also demonstrate the feasibility of lesion characterization on relapsing remitting multiple sclerosis patients.