Imalytics Preclinical can provide functionality for MRI relaxometry. It requires a 4D data set, i.e. 3D images at multiple time points (e.g. echo times). Relaxometry works by curve fitting, i.e. a parameterized curve is fitted to a measurement vector and the parameters are found by a cost function consisting of the squared residuum. During fitting, a small magnitude penalty (0.001*measurements²*R²) is added to the cost term to make the solution more stable.