title: User-initialized active contour segmentation and golden-angle real-time cardiovascular magnetic resonance enable accurate assessment of LV function in patients with sinus rhythm and arrhythmias.
abstract: BACKGROUND
  Data obtained during arrhythmia is retained in real-time cardiovascular magnetic resonance (rt-CMR), but there is limited and inconsistent evidence to show that rt-CMR can accurately assess beat-to-beat variation in left ventricular (LV) function or during an arrhythmia.
  
  
  METHODS
  Multi-slice, short axis cine and real-time golden-angle radial CMR data was collected in 22 clinical patients (18 in sinus rhythm and 4 patients with arrhythmia). A user-initialized active contour segmentation (ACS) software was validated via comparison to manual segmentation on clinically accepted software. For each image in the 2D acquisitions, slice volume was calculated and global LV volumes were estimated via summation across the LV using multiple slices. Real-time imaging data was reconstructed using different image exposure times and frame rates to evaluate the effect of temporal resolution on measured function in each slice via ACS. Finally, global volumetric function of ectopic and non-ectopic beats was measured using ACS in patients with arrhythmias.
  
  
  RESULTS
  ACS provides global LV volume measurements that are not significantly different from manual quantification of retrospectively gated cine images in sinus rhythm patients. With an exposure time of 95.2 ms and a frame rate of > 89 frames per second, golden-angle real-time imaging accurately captures hemodynamic function over a range of patient heart rates. In four patients with frequent ectopic contractions, initial quantification of the impact of ectopic beats on hemodynamic function was demonstrated.
  
  
  CONCLUSIONS
  User-initialized active contours and golden-angle real-time radial CMR can be used to determine time-varying LV function in patients. These methods will be very useful for the assessment of LV function in patients with frequent arrhythmias.
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg 421, 7th Floor, Rm 103, Philadelphia, PA, 1903, USA. fcont@seas.upenn.edu.
authors.forename: Francisco
authors.initials: F
authors.lastname: Contijoch
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA. witschey@mail.med.upenn.edu.
authors.forename: Walter R T
authors.initials: WR
authors.lastname: Witschey
authors.affiliation: Cardiovascular Division, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA. kellyrog@seas.upenn.edu.
authors.forename: Kelly
authors.initials: K
authors.lastname: Rogers
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA. hannahr395@gmail.com.
authors.forename: Hannah
authors.initials: H
authors.lastname: Rears
authors.affiliation: NHLBI, NIH, Bethesda, MD, USA. michael.hansen@nih.gov.
authors.forename: Michael
authors.initials: M
authors.lastname: Hansen
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA. pauly2@mail.med.upenn.edu.
authors.forename: Paul
authors.initials: P
authors.lastname: Yushkevich
authors.affiliation: Department of Surgery, University of Pennsylvania, Philadelphia, PA, 1903, USA. Joseph.Gorman@uphs.upenn.edu.
authors.forename: Joseph
authors.initials: J
authors.lastname: Gorman
authors.affiliation: Department of Surgery, University of Pennsylvania, Philadelphia, PA, 1903, USA. robert.gorman@uphs.upenn.edu.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Gorman
authors.affiliation: Cardiovascular Division, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA. Yuchi.Han@uphs.upenn.edu.
authors.forename: Yuchi
authors.initials: Y
authors.lastname: Han
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000503:physiopathology; D055424:Cardiac-Gated Imaging Techniques; D016022:Case-Control Studies; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012984:Software; D013997:Time Factors; D014584:User-Computer Interface; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000503:physiopathology; D016277:Ventricular Function, Left