1. A method, comprising: controlling a magnetic resonance imaging (MRI) apparatus to apply radio frequency (RF) energy to a volume according to a non-Cartesian three-dimensional (3D) pulse sequence that is configured to cause the volume to produce nuclear magnetic resonance (NMR) signals, the pulse sequence comprising a preparation phase and two or more image acquisition units per preparation phase; controlling the MRI apparatus to acquire a series of 3D data sets of NMR signals from the volume according to a non-Cartesian trajectory; controlling the MRI apparatus to reconstruct the series of 3D data sets into a corresponding series of 3D images using a 3D through-time non-Cartesian generalized auto-calibrating partially parallel acquisitions (GRAPPA) approach: producing a 3D map of at least a portion of the volume based, at least in part, on one or more members of the series of 3D images, where the 3D map is weighted with respect to a magnetic resonance (MR) parameter, and producing a quantitative value for the MR parameter for the portion of the volume based, at least in part, on the 3D map.