title: Cardiovascular magnetic resonance myocardial feature tracking detects quantitative wall motion during dobutamine stress.
abstract: BACKGROUND
  Dobutamine stress cardiovascular magnetic resonance (DS-CMR) is an established tool to assess hibernating myocardium and ischemia. Analysis is typically based on visual assessment with considerable operator dependency. CMR myocardial feature tracking (CMR-FT) is a recently introduced technique for tissue voxel motion tracking on standard steady-state free precession (SSFP) images to derive circumferential and radial myocardial mechanics.We sought to determine the feasibility and reproducibility of CMR-FT for quantitative wall motion assessment during intermediate dose DS-CMR.
  
  
  METHODS
  10 healthy subjects were studied at 1.5 Tesla. Myocardial strain parameters were derived from SSFP cine images using dedicated CMR-FT software (Diogenes MRI prototype; Tomtec; Germany). Right ventricular (RV) and left ventricular (LV) longitudinal strain (EllRV and EllLV) and LV long-axis radial strain (ErrLAX) were derived from a 4-chamber view at rest. LV short-axis circumferential strain (EccSAX) and ErrSAX; LV ejection fraction (EF) and volumes were analyzed at rest and during dobutamine stress (10 and 20 μg · kg⁻¹· min⁻¹).
  
  
  RESULTS
  In all volunteers strain parameters could be derived from the SSFP images at rest and stress. EccSAX values showed significantly increased contraction with DSMR (rest: -24.1 ± 6.7; 10 μg: -32.7 ± 11.4; 20 μg: -39.2 ± 15.2; p < 0.05). ErrSAX increased significantly with dobutamine (rest: 19.6 ± 14.6; 10 μg: 31.8 ± 20.9; 20 μg: 42.4 ± 25.5; p < 0.05). In parallel with these changes; EF increased significantly with dobutamine (rest: 56.9 ± 4.4%; 10 μg: 70.7 ± 8.1; 20 μg: 76.8 ± 4.6; p < 0.05). Observer variability was best for LV circumferential strain (EccSAX ) and worst for RV longitudinal strain (EllRV) as determined by 95% confidence intervals of the difference.
  
  
  CONCLUSIONS
  CMR-FT reliably detects quantitative wall motion and strain derived from SSFP cine imaging that corresponds to inotropic stimulation. The current implementation may need improvement to reduce observer-induced variance. Within a given CMR lab; this novel technique holds promise of easy and fast quantification of wall mechanics and strain.
authors: King's College London British Heart Foundation Centre of Excellence, London, UK. andreas_schuster@gmx.net
authors: Andreas
authors: A
authors: Schuster
authors: Shelby
authors: S
authors: Kutty
authors: Asif
authors: A
authors: Padiyath
authors: Victoria
authors: V
authors: Parish
authors: Paul
authors: P
authors: Gribben
authors: David A
authors: DA
authors: Danford
authors: Marcus R
authors: MR
authors: Makowski
authors: Boris
authors: B
authors: Bigalke
authors: Philipp
authors: P
authors: Beerbaum
authors: Eike
authors: E
authors: Nagel
mesh_terms: D000328:Adult; D002316:Cardiotonic Agents; D004280:Dobutamine; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D015588:Observer Variation; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D013318:Stroke Volume; D016277:Ventricular Function, Left; D055815:Young Adult
chemical_list: D002316:Cardiotonic Agents; D004280:Dobutamine