Magnetic resonance spectroscopy with real-time correction of motion and frequency drift, and real-time shimming

摘要

Disclosed are MR Spectroscopy and MR Spectroscopic Imaging (MRSI) methods comprising the sequential steps of water suppression, spatial prelocalization and spatial-spectral encoding, wherein the water suppression is modified to additionally measure and correct the frequency drift, the change in magnetic field inhomogeneity in the volume of interest, and the object movement. By inserting between the water suppression RF pulse and the dephasing gradient pulses either a phase sensitive MRI encoding module, or a 1D, 2D or 3D high-speed MRSI encoding module with simultaneous acquisition of the decaying water signal it is possible to measure frequency drift, magnetic field inhomogeneity and object movement. This information is used to dynamically change the synthesizer frequency of the scanner, the shim settings and to rotate the encoded k-space. In the preferred implementation this information is computed in real-time during the ongoing scan and via feedback loop downloaded to the acquisition control unit to update the aforementioned parameters before the subsequent data acquisition.