Methods of radio frequency magnetic field mapping

摘要

Methods for measuring B1 values in an MRI sample space, generating B1 maps and using B1 maps to correct B1 profiles are disclosed.

主权项

1. A method for measuring B1 for an MRI sample space comprising:
(a) providing a uniform object in the sample space; (b) generating an excitation pulse, the excitation pulse comprising a low flip angle and an RF pulse duration; (c) acquiring a signal from the excitation pulse wherein the signal is spatially encoded with a phase encode gradient; (d) measuring the intensity of the acquired signal; (e) repeating steps (b) to (d) while varying the phase encode gradient to obtain a phase encoded data set; (f) applying a Fourier transform to the phase encoded data set to generate an MRI image for the specific pulse duration; (g) varying the RF pulse duration and repeating steps (b) to (f); (h) calculating at least two ratios of the signal intensity to at least two different RF pulse durations; and (i) calculating a first slope using at least two of the ratios calculated in step (h), wherein the slope is dependent on B12 for a first location in the object.