title: Myocardial T1 and T2 mapping at 3 T: reference values, influencing factors and implications.
abstract: BACKGROUND
  Myocardial T1 and T2 mapping using cardiovascular magnetic resonance (CMR) are promising to improve tissue characterization and early disease detection. This study aimed at analyzing the feasibility of T1 and T2 mapping at 3 T and providing reference values.
  
  
  METHODS
  Sixty healthy volunteers (30 males/females, each 20 from 20-39 years, 40-59 years, 60-80 years) underwent left-ventricular T1 and T2 mapping in 3 short-axis slices at 3 T. For T2 mapping, 3 single-shot steady-state free precession (SSFP) images with different T2 preparation times were acquired. For T1 mapping, modified Look-Locker inversion recovery technique with 11 single shot SSFP images was used before and after injection of gadolinium contrast. T1 and T2 relaxation times were quantified for each slice and each myocardial segment.
  
  
  RESULTS
  Mean T2 and T1 (pre-/post-contrast) times were: 44.1 ms/1157.1 ms/427.3 ms (base), 45.1 ms/1158.7 ms/411.2 ms (middle), 46.9 ms/1180.6 ms/399.7 ms (apex). T2 and pre-contrast T1 increased from base to apex, post-contrast T1 decreased. Relevant inter-subject variability was apparent (scatter factor 1.08/1.05/1.11 for T2/pre-contrast T1/post-contrast T1). T2 and post-contrast T1 were influenced by heart rate (p < 0.0001, p = 0.0020), pre-contrast T1 by age (p < 0.0001). Inter- and intra-observer agreement of T2 (r = 0.95; r = 0.95) and T1 (r = 0.91; r = 0.93) were high. T2 maps: 97.7% of all segments were diagnostic and 2.3% were excluded (susceptibility artifact). T1 maps (pre-/post-contrast): 91.6%/93.9% were diagnostic, 8.4%/6.1% were excluded (predominantly susceptibility artifact 7.7%/3.2%).
  
  
  CONCLUSIONS
  Myocardial T2 and T1 reference values for the specific CMR setting are provided. The diagnostic impact of the high inter-subject variability of T2 and T1 relaxation times requires further investigation.
authors.forename: Florian
authors.initials: F
authors.lastname: von Knobelsdorff-Brenkenhoff
authors.forename: Marcel
authors.initials: M
authors.lastname: Prothmann
authors.forename: Matthias A
authors.initials: MA
authors.lastname: Dieringer
authors.forename: Ralf
authors.initials: R
authors.lastname: Wassmuth
authors.forename: Andreas
authors.initials: A
authors.lastname: Greiser
authors.forename: Carsten
authors.initials: C
authors.lastname: Schwenke
authors.forename: Thoralf
authors.initials: T
authors.lastname: Niendorf
authors.forename: Jeanette
authors.initials: J
authors.lastname: Schulz-Menger
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D002138:Calibration; D055424:Cardiac-Gated Imaging Techniques; D004562:Electrocardiography; D005240:Feasibility Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000592:standards*; D019028:Magnetic Resonance Imaging, Cine / Q000592:standards*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D013997:Time Factors; D016277:Ventricular Function, Left; D055815:Young Adult