title: The use of contrast-enhanced magnetic resonance imaging to define ischemic injury after reperfusion. Comparison in normal and hypertrophied hearts.
abstract: OBJECTIVE
  Magnetic resonance imaging (MRI) was used to demonstrate the infarction size in reperfused ischemic myocardium of normal and hypertrophied hearts, and to test the hypothesis that hypertrophied hearts manifest greater susceptibility to ischemia.
  
  
  METHODS
  Normal rats (n = 11) and rats subjected to left ventricular hypertrophy (LVH) by aortic banding (n = 13) were studied. After 7 weeks, the left coronary artery was occluded for 25 minutes and reperfused for 1 hour before MRI. Electrocardiogram-gated spin-echo images were acquired before and after administration of 0.3 mmol/kg gadoteridol. To quantify the hyperintense area demarcated by gadoteridol, 3 transaxial images were acquired at different levels. Jeopardy and infarcted areas were measured in the same three slices postmortem using blue dye and triphenyltetrazolium chloride (TTC) stain, respectively.
  
  
  RESULTS
  Before administration, there was no significant difference in signal intensity between nonischemic (0.42 +/- 0.03 arbitrary units) and ischemic (0.41 +/- 0.03) myocardium in either group. After gadoteridol injection, signal intensity of the reperfused injured region was higher than that of nonischemic myocardium (1.48 +/- 0.16 vs. 0.72 +/- 0.06, P < .05). Magnetic resonance delineation of the hyperintense area persisted for at least 30 minutes. The size of the hyperintense area was larger in LVH than in control hearts (25 +/- 5% vs. 7 +/- 3% of LV surface area, P < .05) and did relate closely to the area of myocardial infarction (r = .97), but not with the jeopardy area (r = .42). On TTC staining, the infarction size also was significantly greater in LVH than in normal group (18 +/- 5% vs. 5 +/- 2% of LV surface area, P < .05). The jeopardy areas of normal and LVH hearts showed no significant difference (46 +/- 2% vs. 47 +/- 3%).
  
  
  CONCLUSIONS
  Magnetic resonance imaging confirms the concept that reperfused myocardial injury is larger in LVH than normal hearts after brief coronary occlusion. Contrast-enhanced MRI can define the size of reperfused myocardial injury. Thus, MRI is a suitable technique to assess conditions accentuating ischemic injury.
authors.affiliation: Department of Radiology, University of California, San Francisco.
authors.forename: K
authors.initials: K
authors.lastname: Lauerma
authors.forename: M
authors.initials: M
authors.lastname: Saeed
authors.forename: M F
authors.initials: MF
authors.lastname: Wendland
authors.forename: N
authors.initials: N
authors.lastname: Derugin
authors.forename: K K
authors.initials: KK
authors.lastname: Yu
authors.forename: C B
authors.initials: CB
authors.lastname: Higgins
mesh_terms: D000818:Animals; D003287:Contrast Media; D005682:Gadolinium; D006571:Heterocyclic Compounds; D017379:Hypertrophy, Left Ventricular / Q000150:complications / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015428:Myocardial Reperfusion Injury / Q000150:complications / Q000473:pathology*; D009206:Myocardium / Q000473:pathology*; D009942:Organometallic Compounds; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C062402:gadoteridol; D005682:Gadolinium