title: Measurement of Myocardial T1ρ with a Motion Corrected, Parametric Mapping Sequence in Humans.
abstract: OBJECTIVE
  To develop a robust T1ρ magnetic resonance imaging (MRI) sequence for assessment of myocardial disease in humans.
  
  
  METHODS
  We developed a breath-held T1ρ mapping method using a single-shot, T1ρ-prepared balanced steady-state free-precession (bSSFP) sequence. The magnetization trajectory was simulated to identify sources of T1ρ error. To limit motion artifacts, an optical flow-based image registration method was used to align T1ρ images. The reproducibility and accuracy of these methods was assessed in phantoms and 10 healthy subjects. Results are shown in 1 patient with pre-ventricular contractions (PVCs), 1 patient with chronic myocardial infarction (MI) and 2 patients with hypertrophic cardiomyopathy (HCM).
  
  
  RESULTS
  In phantoms, the mean bias was 1.0 ± 2.7 msec (100 msec phantom) and 0.9 ± 0.9 msec (60 msec phantom) at 60 bpm and 2.2 ± 3.2 msec (100 msec) and 1.4 ± 0.9 msec (60 msec) at 80 bpm. The coefficient of variation (COV) was 2.2 (100 msec) and 1.3 (60 msec) at 60 bpm and 2.6 (100 msec) and 1.4 (60 msec) at 80 bpm. Motion correction improved the alignment of T1ρ images in subjects, as determined by the increase in Dice Score Coefficient (DSC) from 0.76 to 0.88. T1ρ reproducibility was high (COV < 0.05, intra-class correlation coefficient (ICC) = 0.85-0.97). Mean myocardial T1ρ value in healthy subjects was 63.5 ± 4.6 msec. There was good correspondence between late-gadolinium enhanced (LGE) MRI and increased T1ρ relaxation times in patients.
  
  
  CONCLUSIONS
  Single-shot, motion corrected, spin echo, spin lock MRI permits 2D T1ρ mapping in a breath-hold with good accuracy and precision.
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Berisha
authors.affiliation: Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Joyce
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Shahid
authors.affiliation: Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Yuchi
authors.initials: Y
authors.lastname: Han
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Walter R T
authors.initials: WR
authors.lastname: Witschey
mesh_terms: D000328:Adult; D016477:Artifacts; D062485:Breath Holding; D002312:Cardiomyopathy, Hypertrophic / Q000473:pathology; D005260:Female; D005682:Gadolinium / Q000008:administration & dosage; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009038:Motion; D009203:Myocardial Infarction / Q000473:pathology*; D009206:Myocardium / Q000473:pathology*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results
chemical_list: D005682:Gadolinium