Daniel L. Shefchik1, Andrew S. Nencka1, Andrzej Jesmanowicz1, James S. Hyde1
1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States
The accelerated gradient-recalled echo, asymmetric spin-echo pulse sequence was developed to produce relaxivity maps with the same EPI readouts used in functional studies. The sequence had the ability to calculate T1, T2 and T2* voxel-wise relaxivity maps from a single excitation utilizing echo pairs. These echo pair calculations led to systematic errors due to low SNR for T2 and T2* echo pairs and the inaccuracy of the flip angles. A new non-linear model was developed which greatly increase the accuracy of the EPI collected relaxivity maps, while maintaining the ability to provide precise dynamic time series T2 and T2* maps.