title: Creating hemodynamic atlases of cardiac 4D flow MRI.
abstract: Hemodynamic atlases can add to the pathophysiological understanding of cardiac diseases. This study proposes a method to create hemodynamic atlases using 4D Flow magnetic resonance imaging (MRI). The method is demonstrated for kinetic energy (KE) and helicity density (Hd).
  
  
  
  Thirteen healthy subjects underwent 4D Flow MRI at 3T. Phase-contrast magnetic resonance cardioangiographies (PC-MRCAs) and an average heart were created and segmented. The PC-MRCAs, KE, and Hdwere nonrigidly registered to the average heart to create atlases. The method was compared with 1) rigid, 2) affine registration of the PC-MRCAs, and 3) affine registration of segmentations. The peak and mean KE and Hdbefore and after registration were calculated to evaluate interpolation error due to nonrigid registration.
  
  
  
  The segmentations deformed using nonrigid registration overlapped (median: 92.3%) more than rigid (23.1%, P < 0.001), and affine registration of PC-MRCAs (38.5%, P < 0.001) and affine registration of segmentations (61.5%, P < 0.001). The peak KE was 4.9 mJ using the proposed method and affine registration of segmentations (P = 0.91), 3.5 mJ using rigid registration (P < 0.001), and 4.2 mJ using affine registration of the PC-MRCAs (P < 0.001). The mean KE was 1.1 mJ using the proposed method, 0.8 mJ using rigid registration (P < 0.001), 0.9 mJ using affine registration of the PC-MRCAs (P < 0.001), and 1.0 mJ using affine registration of segmentations (P = 0.028). The interpolation error was 5.2 ± 2.6% at mid-systole, 2.8 ± 3.8% at early diastole for peak KE; 9.6 ± 9.3% at mid-systole, 4.0 ± 4.6% at early diastole, and 4.9 ± 4.6% at late diastole for peak Hd. The mean KE and Hdwere not affected by interpolation.
  
  
  
  Hemodynamic atlases can be obtained with minimal user interaction using nonrigid registration of 4D Flow MRI.
  
  
  
  2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1389-1399.
authors.affiliation: Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.|Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.
authors.forename: Merih
authors.initials: M
authors.lastname: Cibis
authors.affiliation: Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.|Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.
authors.forename: Mariana
authors.initials: M
authors.lastname: Bustamante
authors.affiliation: Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Jonatan
authors.initials: J
authors.lastname: Eriksson
authors.affiliation: Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.|Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.|Division of Clinical Physiology, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Carl-Johan
authors.initials: CJ
authors.lastname: Carlhäll
authors.affiliation: Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.|Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.
authors.forename: Tino
authors.initials: T
authors.lastname: Ebbers
mesh_terms: D000328:Adult; D000792:Angiography; D003971:Diastole; D005260:Female; D006321:Heart / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D057446:Hydrodynamics; D007700:Kinetics; D008279:Magnetic Resonance Imaging; D008297:Male; D008858:Microscopy, Phase-Contrast; D012016:Reference Values; D013318:Stroke Volume; D013599:Systole; D016277:Ventricular Function, Left; D055815:Young Adult
keywords: 4D Flow MRI; cardiac flow; helicity density; hemodynamic atlas; kinetic energy; nonrigid registration