Phosphorus-31: A table-top method for 3D B₁-field amplitude and phase measurements

A novel method of high-spatial-resolution, 3D B₁-field distribution measurements is presented. The method is independent of the MR-scanner, and it allows for automated acquisitions of complete maps of all magnetic field vector components for both proton and heteronuclear MR coils of arbitrary geometrical shapes. The advantage of the method proposed here, compared with methods based on measurements with an MR-scanner, is that a complete image of both receive and transmit B₁-fields, including the phase of the B₁-field, can be acquired. The B₁ field maps obtained in this manner can be used for absolute quantification of metabolites in MRS experiments, as well as for intensity compensations in imaging experiments, both of which are important concepts in biological and medical MR applications. Another use might be in coil development and testing. A comparison with B₁ field magnitude maps obtained with an MR-scanner was included to validate the accuracy of the proposed method.