title: Myocardial tagging and strain analysis at 3 Tesla: comparison with 1.5 Tesla imaging.
abstract: OBJECTIVE
  To determine whether imaging at 3 T could improve and prolong the tag contrast compared to images acquired at 1.5 T in normal volunteers, and whether such improvement would translate into the ability to perform strain measurements in diastole.
  
  
  METHODS
  Normal volunteers (N = 13) were scanned at 1.5 T (GE Signa CV/i) and 3.0 T (GE VH/i). An ECG-triggered, segmented k-space, spoiled-gradient-echo grid-tagged sequence was used during cine acquisition. Tag contrast was determined by the difference of the mean signal intensity (SI) of the tagline to the mean SI of the myocardium divided by the standard deviation (SD) of the noise (CNR(tag)). Matched short-axis (SA) slices were analyzed. Strain measurements were performed on images using a 2D strain analysis software program (harmonic phase (HARP)).
  
  
  RESULTS
  The average CNR(tag) over the cardiac cycle was superior at 3 T compared to 1.5 T for all slices (3 T: 23.4 +/- 12.1, 1.5 T: 9.8 +/- 8.4; P < 0.0001). This difference remained significant at cycle initiation, end-systole, and the end R-R interval (at cycle termination: 3 T = 14.0 +/- 11.0 vs. 1.5 T = 4.4 +/- 3.5; P < 0.01). Strain measures were obtainable only in early systole for 1.5 T images, but were robust throughout the entire R-R interval for 3 T images.
  
  
  CONCLUSIONS
  Imaging at 3 T had a significant benefit for myocardial tag persistence through the cardiac cycle. The improvement allowed strain analysis to be performed into diastole.
authors.affiliation: Department of Medicine, Mayo Clinic and Foundation, Rochester, Minnesota, USA.
authors.forename: V Uma
authors.initials: VU
authors.lastname: Valeti
authors.forename: Wookjin
authors.initials: W
authors.lastname: Chun
authors.forename: Donald D
authors.initials: DD
authors.lastname: Potter
authors.forename: Philip A
authors.initials: PA
authors.lastname: Araoz
authors.forename: Kiaran P
authors.initials: KP
authors.lastname: McGee
authors.forename: James F
authors.initials: JF
authors.lastname: Glockner
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Christian
mesh_terms: D000328:Adult; D005260:Female; D006321:Heart / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction