BIR-4-S2 ADIABATIC RF PULSES, USE THEREFOR AND METHOD OF CREATING THE SAME

摘要

Adiabatic RF pulses are very useful in MRI when precise flip angles are needed. Unfortunately, adiabatic pulses suffer from a long application time and a high SAR. In this article, we introduce a new concept to modify the usual adiabatic pulse into a "pseudo-adiabatic" pulse having a shorter application time and lower SAR. For example, a BIR-4 of 32 ms of application time and a relative SAR of 20 will be transformed into a BIR-4-S1 of 1 ms and relative SAR of 1. The new pulse obtained stays insensitive for a large B1 range but loses its slice selectivity to become a 3D pulse. Experimental results are presented to illustrate the sensitivity to B1 and B0.