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

An optimized multislice data acquisition scheme for phase acquisition of co mposite echoes (PACE) imaging is presented. This new scheme uses a repetiti on time equal to the mixing time and an appropriate phase cycling scheme, w hich 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 met hod. Moreover, T-1 values can be obtained directly from phase images withou t 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 f ast PACE technique compared with a conventional two point method in multisl ice acquisition mode, although precision was limited at high T-1 values. T- 1 and T-1sat measurements in brain tissue of eight healthy volunteers confi rmed the stability of the fast PACE technique in a clinical setting. (C) 19 99 Wiley-Liss, Inc.