Fast multislice T1 and T(1sat) imaging using a phase acquisition of composite echoes (PACE) technique

Abstract

An optimized multislice data acquisition scheme for phase acquisition of composite echoes (PACE) imaging is presented. This new scheme uses a repetition time equal to the mixing time and an appropriate phase cycling scheme, which allows for more efficient exploitation of all composite echoes. These modifications provide true multislice capability in parallel to a reduction of the acquisition time by a factor >2 compared with the original PACE method. Moreover, T1 values can be obtained directly from phase images without the use of a lookup table. Because of the symmetrical application of the radio frequency pulses, this method is also well suited for T(1sat) imaging. Phantom studies showed a significantly better accuracy of the multislice fast PACE technique compared with a conventional two-point method in multislice acquisition mode, although precision was limited at high T1 values. T1 and T(1sat) measurements in brain tissue of eight healthy volunteers confirmed the stability of the fast PACE technique in a clinical setting.