title: Effect of free-breathing on left ventricular rotational mechanics in healthy subjects and patients with duchenne muscular dystrophy.
abstract: Cardiovascular magnetic resonance imaging exams can be performed during free-breathing. This may be especially important for boys with Duchenne muscular dystrophy (DMD) given their frequently limited breath-hold abilities. The impact of the respiratory compensation method on quantitative measurements of left ventricular (LV) rotational mechanics is incompletely understood. The purpose of this study was to evaluate differences in LV rotational mechanics acquired during breath-holding (BH), free-breathing with averaging (AVG), and free-breathing with respiratory bellows gating (BEL).
  
  
  
  LV short-axis tagged images from healthy subjects (N = 16) and DMD patients (N = 5) were acquired with BH, AVG, and BEL. LV twist and circumferential-longitudinal shear (CL-shear) angle were measured using the Fourier Analysis of STimulated echoes (FAST) method.
  
  
  
  Peak LV twist estimates using BEL were significantly lower compared with BH in both healthy subjects (10.2 ± 3.6 ° versus 12.9 ± 2.3 °, P = 0.003) and patients with DMD (8.6 ± 3.6 ° versus 10.5 ± 3.6 °, P = 0.004). AVG results were in between BEL and BH. No significant differences in CL-shear were detected between BEL and BH.
  
  
  
  Breath-holding directly affects estimates of peak LV twist, but not CL-shear. Using a free-breathing strategy for the evaluation of cardiac function is important for intrasubject longitudinal studies, intersubject comparisons, and multicenter trials for patients with DMD. Magn Reson Med 77:864-869, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Radiological Sciences, University of California, Los Angeles, California, USA.|Biomedical Physics Interdepartmental Program, University of California, Los Angeles, California, USA.
authors.forename: Meral L
authors.initials: ML
authors.lastname: Reyhan
authors.affiliation: Department of Radiological Sciences, University of California, Los Angeles, California, USA.|Department of Bioengineering, University of California, Los Angeles, California, USA.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Radiological Sciences, University of California, Los Angeles, California, USA.|Biomedical Physics Interdepartmental Program, University of California, Los Angeles, California, USA.|Department of Biostatistics, University of California, Los Angeles, California, USA.
authors.forename: Hyun J
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Medicine (Pediatric Cardiology), University of California, Los Angeles, California, USA.
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Halnon
authors.affiliation: Department of Radiological Sciences, University of California, Los Angeles, California, USA.|Biomedical Physics Interdepartmental Program, University of California, Los Angeles, California, USA.
authors.forename: J Paul
authors.initials: JP
authors.lastname: Finn
authors.affiliation: Department of Radiological Sciences, University of California, Los Angeles, California, USA.|Biomedical Physics Interdepartmental Program, University of California, Los Angeles, California, USA.|Department of Bioengineering, University of California, Los Angeles, California, USA.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Ennis
mesh_terms: D000328:Adult; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D020388:Muscular Dystrophy, Duchenne / Q000000981:diagnostic imaging*; D015656:Respiratory Mechanics / Q000502:physiology*; D055815:Young Adult
keywords: Duchenne muscular dystrophy; free-breathing; shear angle; tagging; torsion; twist