Imaging of the active B1 field in vivo

Abstract

The authors describe a method for accurate In vivo muttislice imaging of the active component of the B₁ field which is based on a previously proposed method, which uses the signal intensity ratio of two images measured with different excitation angles, and a repetition time TR≥ 5 T₁ The new method essentially reduces repetition and scan time by means of an additional compensating pulse. The suppression of T₁ effects by this pulse are verified with simulations and measurements. Further investigations concerned the influence of slice selective excitation and magnetization transfer in multislice imaging to the B₁ field determination. The stability and accuracy of the presented method is shown by several phantom and in vivo measurements. With the described method the active B₁ field can be determined in vivo in 23 cross-sections in less than 6 min.