Artifact-suppressed optimal three-dimensional T1- and T2*-weighted dual-echo imaging

Abstract

Purpose: To develop a new artifact-suppressed optimal three-dimensional (3D) T1- and T2*-weighted dual-echo imaging. Methods: We optimized flip angles for 3D T1- and T2*-weighted imaging by conventional dual-echo in vivo experiments and computer simulations, and then implemented a dual-echo sequence with an echo-specific k-space reordering scheme to satisfy the optimal flip angles for both T1 and T2* contrast. We also proposed two strategies to suppress ringing artifacts induced by the abrupt flip angle jumps in the proposed dual echo sequence: (i) implementing smooth transition regions and (ii) discarding the k-space regions of the abrupt flip angle jumps as dummy phase-encoding steps. Results: The optimal flip angles measured from experiments were different between T1- and T2*-weighted contrast, in agreement with simulations. The echo-specific k-space reordered dual-echo sequence showed optimal T1 and T2* contrast simultaneously, but also showed ringing artifacts because of high flip-angle changes between k-space regions. The two proposed strategies effectively suppressed the ringing artifacts. Conclusion: The proposed 3D dual-echo sequence provided optimal T1 and T2* contrast simultaneously with no artifacts and thus is potentially applicable to routine clinical applications for simultaneous high resolution T1- and T2*-weighted imaging. Magn Reson Med 76:1504–1511, 2016. © 2015 International Society for Magnetic Resonance in Medicine.