title: Artifact-suppressed optimal three-dimensional T1- and T2*-weighted dual-echo imaging.
abstract: To develop a new artifact-suppressed optimal three-dimensional (3D) T1- and T2*-weighted dual-echo imaging.
  
  
  
  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 T1and 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.
  
  
  
  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 T1and 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.
  
  
  
  The proposed 3D dual-echo sequence provided optimal T1and 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.
authors.affiliation: MRI Laboratory, Department of Bio and Brian Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea.
authors.forename: Won-Joon
authors.initials: WJ
authors.lastname: Do
authors.affiliation: MRI Laboratory, Department of Bio and Brian Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea.|Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea.
authors.forename: Ki Hwan
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Seung Hong
authors.initials: SH
authors.lastname: Choi
authors.affiliation: MRI Laboratory, Department of Bio and Brian Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea. sunghongpark@kaist.ac.kr.
authors.forename: Sung-Hong
authors.initials: SH
authors.lastname: Park
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods; D017352:Echo-Planar Imaging / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
keywords: CODEA; T1; T2*; dual echo sequence; echo-specific k-space reordering