Fast multicomponent 3D‐T1ρ relaxometry

NMR relaxometry can provide information about the relaxation of the magnetization in different tissues, increasing our understanding of molecular dynamics and biochemical composition in biological systems. In general, tissues have complex and heterogeneous structures composed of multiple pools. As a result, bulk magnetization returns to its original state with different relaxation times, in a multicomponent relaxation. Recovering the distribution of relaxation times in each voxel is a difficult inverse problem; it is usually unstable and requires long acquisition time, especially on clinical scanners. MRI can also be viewed as an inverse problem, especially when compressed sensing (CS) is used. The solution of these two inverse problems, CS and relaxometry, can be obtained very efficiently in a synergistically combined manner, leading to a more stable multicomponent relaxometry obtained with short scan times. In this paper, we will discuss the details of this technique from the viewpoint of inverse problems. MR relaxometry can increase our understanding of molecular dynamics and biochemical composition of biological tissues, showing the distribution of relaxation times within specific regions of interest or voxels. This process, which usually requires a long scan time, can be combined synergistically with fast imaging, leading to a more stable multicomponent relaxometry with remarkably fast scan times. This paper discusses this joint task from the viewpoint of inverse problems.