Diffusion mapping by MR fingerprinting

A magnetic resonance (MR) system comprising:

• at least one main magnet coil configured to generate a main magnetic field within an examination volume, a number of gradient coils configured to generate switched magnetic field gradients in different spatial directions within the examination volume, at least one RF coil configured to generate RF pulses within the examination volume and/or for receiving MR signals from an object (10) positioned in the examination volume, a control computer configured to control a temporal succession of RF pulses and switched magnetic field gradients based on an examination protocol, and a reconstruction unit configured to reconstruct MR images from the received MR signals, wherein the MR system is configured to:
• subject the object to an imaging sequence composed of a train of sequence blocks, each sequence block comprising at least one RF pulse, at least one switched spoiling magnetic field gradient and at least one switched readout magnetic field gradient defining a k-space sampling pattern, and having associated therewith a set of acquisition parameters including the zeroth moment of the spoiling magnetic field gradient,
• the imaging sequence including two or more types of sequence blocks, wherein each type is assigned a fixed value of the zeroth moment of the spoiling magnetic field gradient and the fixed values are pairwise coprime integer multiples of a unit spoiling gradient value,
• acquire the MR signals while varying at least the zeroth moment of the spoiling magnetic field gradient and, optionally, one or more further acquisition parameters during the course of the imaging sequence, and
• reconstruct at least one MR image, wherein at least a diffusion coefficient and, optionally, one or more further MR parameters are computed for a number of image positions from an incoherent temporal evolution of the acquired MR signals caused by the variation of the at least one acquisition parameter.