title: Assessment of myocardial injury after reperfused infarction by T1ρ cardiovascular magnetic resonance.
abstract: BACKGROUND
  The evolution of T1ρ and of other endogenous contrast methods (T2, T1) in the first month after reperfused myocardial infarction (MI) is uncertain. We conducted a study of reperfused MI in pigs to serially monitor T1ρ, T2 and T1 relaxation, scar size and transmurality at 1 and 4 weeks post-MI.
  
  
  METHODS
  Ten Yorkshire swine underwent 90 min of occlusion of the circumflex artery and reperfusion. T1ρ, T2 and native T1 maps and late gadolinium enhanced (LGE) cardiovascular magnetic resonance (CMR) data were collected at 1 week (n = 10) and 4 weeks (n = 5). Semi-automatic FWHM (full width half maximum) thresholding was used to assess scar size and transmurality and compared to histology. Relaxation times and contrast-to-noise ratio were compared in healthy and remote myocardium at 1 and 4 weeks. Linear regression and Bland-Altman was performed to compare infarct size and transmurality.
  
  
  RESULTS
  Relaxation time differences between infarcted and remote myocardial tissue were ∆T1 (infarct-remote) = 421.3 ± 108.8 (1 week) and 480.0 ± 33.2 ms (4 week), ∆T1ρ = 68.1 ± 11.6 and 74.3 ± 14.2, and ∆T2 = 51.0 ± 10.1 and 59.2 ± 11.4 ms. Contrast-to-noise ratio was CNRT1= 7.0 ± 3.5 (1 week) and 6.9 ± 2.4 (4 week), CNRT1ρ= 12.0 ± 6.2 and 12.3 ± 3.2, and CNRT2= 8.0 ± 3.6 and 10.3 ± 5.8. Infarct size was not significantly different for T1ρ, T1 and T2 compared to LGE (p = 0.14) and significantly decreased from 1 to 4 weeks (p < 0.01). Individual infarct size changes were ∆T1ρ = -3.8%, ∆T1 = -3.5% and ∆LGE = -2.8% from 1 - 4 weeks, but there was no observed change in infarct size for T2 or histologically.
  
  
  CONCLUSIONS
  T1ρ was highly correlated with alterations left ventricle (LV) pathology at 1 and 4 weeks post-MI and therefore it may be a useful method endogenous contrast imaging of infarction.
authors.affiliation: Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA.|Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Rutger H
authors.initials: RH
authors.lastname: Stoffers
authors.affiliation: Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA.
authors.forename: Marie
authors.initials: M
authors.lastname: Madden
authors.affiliation: Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Shahid
authors.affiliation: Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Francisco
authors.initials: F
authors.lastname: Contijoch
authors.affiliation: Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Solomon
authors.affiliation: Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: Pilla
authors.affiliation: Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Gorman
authors.affiliation: Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Gorman
authors.affiliation: Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA. witschey@mail.med.upenn.edu.
authors.forename: Walter R T
authors.initials: WRT
authors.lastname: Witschey
mesh_terms: D000818:Animals; D001706:Biopsy; D002921:Cicatrix / Q000000981:diagnostic imaging* / Q000473:pathology; D003287:Contrast Media / Q000008:administration & dosage; D004195:Disease Models, Animal; D016014:Linear Models; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008536:Meglumine / Q000008:administration & dosage / Q000031:analogs & derivatives; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000473:pathology*; D009942:Organometallic Compounds / Q000008:administration & dosage; D011237:Predictive Value of Tests; D059629:Signal-To-Noise Ratio; D013318:Stroke Volume; D034421:Sus scrofa; D013997:Time Factors; D016277:Ventricular Function, Left
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C064572:gadobenic acid; D008536:Meglumine