title: Evaluation of left ventricular ejection fraction using through-time radial GRAPPA.
abstract: BACKGROUND
  The determination of left ventricular ejection fraction using cardiovascular magnetic resonance (CMR) requires a steady cardiac rhythm for electrocardiogram (ECG) gating and multiple breathholds to minimize respiratory motion artifacts, which often leads to scan times of several minutes. The need for gating and breathholding can be eliminated by employing real-time CMR methods such as through-time radial GRAPPA. The aim of this study is to compare left ventricular cardiac functional parameters obtained using current gold-standard breathhold ECG-gated functional scans with non-gated free-breathing real-time imaging using radial GRAPPA, and to determine whether scan time or the occurrence of artifacts are reduced when using this real-time approach.
  
  
  METHODS
  63 patients were scanned on a 1.5T CMR scanner using both the standard cardiac functional examination with gating and breathholding and the real-time method. Total scan durations were noted. Through-time radial GRAPPA was employed to reconstruct images from the highly accelerated real-time data. The blood volume in the left ventricle was assessed to determine the end systolic volume (ESV), end diastolic volume (EDV), and ejection fraction (EF) for both methods, and images were rated for the presence of artifacts and quality of specific image features by two cardiac readers. Linear regression analysis, Bland-Altman plots and two-sided t-tests were performed to compare the quantitative parameters. A two-sample t-test was performed to compare the scan durations, and a two-sample test of proportion was used to analyze the presence of artifacts. For the reviewers´ ratings the Wilcoxon test for the equality of the scores' distributions was employed.
  
  
  RESULTS
  The differences in EF, EDV, and ESV between the gold-standard and real-time methods were not statistically significant (p-values of 0.77, 0.82, and 0.97, respectively). Additionally, the scan time was significantly shorter for the real-time data collection (p<0.001) and fewer artifacts were reported in the real-time images (p<0.01). In the qualitative image analysis, reviewers marginally preferred the standard images although some features including cardiac motion were equivalently rated.
  
  
  CONCLUSIONS
  Real-time functional CMR with through-time radial GRAPPA performed without ECG-gating under free-breathing can be considered as an alternative to gold-standard breathhold cine imaging for the evaluation of ejection fraction in patients.
authors.affiliation: Radiology, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, USA. gunhildaandal@yahoo.no.|Haraldsplass Deaconess Hospital, Bergen, Norway. gunhildaandal@yahoo.no.
authors.forename: Gunhild
authors.initials: G
authors.lastname: Aandal
authors.affiliation: Cardiology, MetroHealth Medical Center at Case Western University, Cleveland, OH, USA. lilnadig@yahoo.co.in.
authors.forename: Vidya
authors.initials: V
authors.lastname: Nadig
authors.affiliation: Case Western Reserve University School of Medicine, Cleveland, OH, USA. vxy16@case.edu.
authors.forename: Victoria
authors.initials: V
authors.lastname: Yeh
authors.affiliation: Radiology, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, USA. Prabhakar.Rajiah@UHhospitals.org.
authors.forename: Prabhakar
authors.initials: P
authors.lastname: Rajiah
authors.affiliation: Division of Cardiovascular Medicine, Harrington Heart & Vascular Institute, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH, USA. Trevor.Jenkins@UHhospitals.org.
authors.forename: Trevor
authors.initials: T
authors.lastname: Jenkins
authors.affiliation: Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, OH, USA. axs879@case.edu.
authors.forename: Abdus
authors.initials: A
authors.lastname: Sattar
authors.affiliation: Radiology, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, USA. mag46@case.edu.|Biomedical Engineering, Case Western Reserve University, Room 309 Wickenden Building 2071 Martin Luther King Jr. Drive, Cleveland, OH, 44106-7207, USA. mag46@case.edu.
authors.forename: Mark
authors.initials: M
authors.lastname: Griswold
authors.affiliation: Radiology, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, USA. vxg46@case.edu.|Biomedical Engineering, Case Western Reserve University, Room 309 Wickenden Building 2071 Martin Luther King Jr. Drive, Cleveland, OH, 44106-7207, USA. vxg46@case.edu.
authors.forename: Vikas
authors.initials: V
authors.lastname: Gulani
authors.affiliation: Radiology, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, USA. Robert.Gilkeson@UHhospitals.org.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Gilkeson
authors.affiliation: Biomedical Engineering, Case Western Reserve University, Room 309 Wickenden Building 2071 Martin Luther King Jr. Drive, Cleveland, OH, 44106-7207, USA. nes30@case.edu.
authors.forename: Nicole
authors.initials: N
authors.lastname: Seiberlich
mesh_terms: D016477:Artifacts; D062485:Breath Holding; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D004562:Electrocardiography; D006339:Heart Rate; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015588:Observer Variation; D009820:Ohio; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left