title: Real-time cardiovascular magnetic resonance at 1.5 T using balanced SSFP and 40 ms resolution.
abstract: BACKGROUND
  While cardiovascular magnetic resonance (CMR) commonly employs ECG-synchronized cine acquisitions with balanced steady-state free precession (SSFP) contrast at 1.5 T, recent developments at 3 T demonstrate significant potential for T1-weighted real-time imaging at high spatiotemporal resolution using undersampled radial FLASH. The purpose of this work was to combine both ideas and to evaluate a corresponding real-time CMR method at 1.5 T with SSFP contrast.
  
  
  METHODS
  Radial gradient-echo sequences with fully balanced gradients and at least 15-fold undersampling were implemented on two CMR systems with different gradient performance. Image reconstruction by regularized nonlinear inversion (NLINV) was performed offline and resulted in real-time SSFP CMR images at a nominal resolution of 1.8 mm and with acquisition times of 40 ms.
  
  
  RESULTS
  Studies of healthy subjects demonstrated technical feasibility in terms of robustness and general image quality. Clinical applicability with access to quantitative evaluations (e.g., ejection fraction) was confirmed by preliminary applications to 27 patients with typical indications for CMR including arrhythmias and abnormal wall motion. Real-time image quality was slightly lower than for cine SSFP recordings, but considered diagnostic in all cases.
  
  
  CONCLUSIONS
  Extending conventional cine approaches, real-time radial SSFP CMR with NLINV reconstruction provides access to individual cardiac cycles and allows for studies of patients with irregular heartbeat.
authors.affiliation: Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, 37070, Göttingen, Germany. jfrahm@gwdg.de.
authors.forename: Dirk
authors.initials: D
authors.lastname: Voit
authors.forename: Shuo
authors.initials: S
authors.lastname: Zhang
authors.forename: Christina
authors.initials: C
authors.lastname: Unterberg-Buchwald
authors.forename: Jan M
authors.initials: JM
authors.lastname: Sohns
authors.forename: Joachim
authors.initials: J
authors.lastname: Lotz
authors.forename: Jens
authors.initials: J
authors.lastname: Frahm
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D004562:Electrocardiography; D005240:Feasibility Studies; D005260:Female; D006339:Heart Rate; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D011237:Predictive Value of Tests; D012016:Reference Values; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left; D055815:Young Adult
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