title: Inter-study reproducibility of cardiovascular magnetic resonance tagging.
abstract: BACKGROUND
  The aim of this study is to determine the test-retest reliability of the measurement of regional myocardial function by cardiovascular magnetic resonance (CMR) tagging using spatial modulation of magnetization.
  
  
  METHODS
  Twenty-five participants underwent CMR tagging twice over 12 ± 7 days. To assess the role of slice orientation on strain measurement, two healthy volunteers had a first exam, followed by image acquisition repeated with slices rotated ±15 degrees out of true short axis, followed by a second exam in the true short axis plane. To assess the role of slice location, two healthy volunteers had whole heart tagging. The harmonic phase (HARP) method was used to analyze the tagged images. Peak midwall circumferential strain (Ecc), radial strain (Err), Lambda 1, Lambda 2, and Angle α were determined in basal, mid and apical slices. LV torsion, systolic and early diastolic circumferential strain and torsion rates were also determined.
  
  
  RESULTS
  LV Ecc and torsion had excellent intra-, interobserver, and inter-study intra-class correlation coefficients (ICC range, 0.7 to 0.9). Err, Lambda 1, Lambda 2 and angle had excellent intra- and interobserver ICC than inter-study ICC. Angle had least inter-study reproducibility. Torsion rates had superior intra-, interobserver, and inter-study reproducibility to strain rates. The measurements of LV Ecc were comparable in all three slices with different short axis orientations (standard deviation of mean Ecc was 0.09, 0.18 and 0.16 at basal, mid and apical slices, respectively). The mean difference in LV Ecc between slices was more pronounced in most of the basal slices compared to the rest of the heart.
  
  
  CONCLUSIONS
  Intraobserver and interobserver reproducibility of all strain and torsion parameters was excellent. Inter-study reproducibility of CMR tagging by SPAMM varied between different parameters as described in the results above and was superior for Ecc and LV torsion. The variation in LV Ecc measurement due to altered slice orientation is negligible compared to the variation due to slice location.
  
  
  BACKGROUND
  This trial is registered as NCT00005487 at National Heart, Lung and Blood institute.
authors.forename: Sirisha
authors.initials: S
authors.lastname: Donekal
authors.forename: Bharath
authors.initials: B
authors.lastname: Ambale-Venkatesh
authors.forename: Seth
authors.initials: S
authors.lastname: Berkowitz
authors.forename: Colin O
authors.initials: CO
authors.lastname: Wu
authors.forename: Eui Young
authors.initials: EY
authors.lastname: Choi
authors.forename: Veronica
authors.initials: V
authors.lastname: Fernandes
authors.forename: Raymond
authors.initials: R
authors.lastname: Yan
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Harouni
authors.forename: David A
authors.initials: DA
authors.lastname: Bluemke
authors.forename: Joao A C
authors.initials: JA
authors.lastname: Lima
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002318:Cardiovascular Diseases / Q000175:diagnosis* / Q000208:ethnology / Q000503:physiopathology; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D015588:Observer Variation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D013314:Stress, Mechanical; D013997:Time Factors; D054159:Torsion, Mechanical; D014481:United States / Q000453:epidemiology; D016277:Ventricular Function, Left