Leland Stanford Junior University

University of Illinois

Anh Tu Van

Roland Bammer

Bradley P Sutton

Diego Hernando

Rafael O'Halloran

Phase error in MR imaging is corrected in real time by providing adaptive RF pulses and corresponding adaptive magnetic field gradients to mitigate the effect of phase error in the imaging subject. A real time phase error map is obtained, and then adaptive RF pulses and corresponding field gradients are applied that remove the problematic effects of the phase error. Depending on details of the MR imaging mode being employed, there are several ways this removal can be done. Phase error can be cancelled by providing RF pulses that make the phase in the imaging subject uniform. Another approach is to make the adaptive RF pulses insensitive to the phase errors that are present.

Apparatus for real-time phase correction for diffusion-weighted magnetic resonance imaging using adaptive RF pulses

A method for correcting motion-induced phase errors in diffusion-weighted k-space data acquired with a magnetic resonance imaging (MRI) system is provided. The MRI system is directed to acquire the following data from an imaging volume: three-dimensional diffusion-weighted k-space data, three-dimensional diffusion-weighted navigator data, three-dimensional non-diffusion-weighted k-space data, and three-dimensional non-diffusion-weighted navigator data. Initial estimates of k-space shift values and a constant phase offset value are calculated using the three-dimensional diffusion-weighted navigator data and the three-dimensional non-diffusion-weighted navigator data. These initial k-space shift values and constant phase offset value are then updated by iteratively minimizing a cost function that relates the phase of the diffusion-weighted k-space data to the phase of the non-diffusion-weighted k-space data, as shifted by the initial k-space shift values and constant phase offset value. The diffusion-weighted k-space data is then corrected for motion-induced phase errors using the updated k-space shift values and constant phase offset value.

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Anh Tu Van