1Electrical Engineering and Computer Science, The University of Michigan-Ann Arbor, Ann Arbor, MI, United States; 2Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, United States; 3Biomedical Engineering, The University of Michigan-Ann Arbor, Ann Arbor, MI, United States
Small tip fast recovery (STFR) imaging has been proposed recently as a potential alternative to balanced steady state free precession (bSSFP). STFR relies on a tailored tip-up RF pulse to achieve comparable signal level and image contrast as bSSFP, but with reduced banding artifacts. 2D STFR imaging can use fast 2D tailored pulses (e.g., spiral) in combination with RF-spoiling, but in many applications such as fMRI it is necessary to do 3D imaging. Designing a 3D RF pulse that accurately tailors the excitation pattern to the local B0 inhomogeneity over the entire imaging volume is a challenging and unsolved problem. Here we propose two complementary strategies for improved 3D STFR imaging: First we show that unbalanced non-RF-spoiled STFR imaging (G-STFR) is less sensitive to tip-up pulse error than the corresponding RF-spoiled sequence (RF-STFR). Second, we propose to use non-slice-selective tailored pulses for both tip-down and tip-up, and present two alternative RF pulse design algorithms.