IMAGING OF THE ACTIVE B-1 FIELD IN-VIVO

The authors describe a method for accurate in vivo multislice imaging of the active component of the B-1 field which is based on a previousl y proposed method, which uses the signal intensity ratio of two images measured with different excitation angles, and a repetition time TR g reater than or equal to 5 T-1. The new method essentially reduces repe tition and scan time by means of an additional compensating pulse, The suppression of T-1 effects by this pulse are verified with simulation s and measurements, Further investigations concerned the influence of slice selective excitation and magnetization transfer in multislice im aging to the B-1 field determination, The stability and accuracy of th e presented method is shown by several phantom and in vivo measurement s, With the described method the active B-1 field can be determined in vivo in 23 cross-sections in less than 6 min.