title: Mechanisms for overestimating acute myocardial infarct size with gadolinium-enhanced cardiovascular magnetic resonance imaging in humans: a quantitative and kinetic study.
abstract: OBJECTIVE
  It remains controversial whether cardiovascular magnetic resonance imaging with gadolinium only enhances acutely infarcted or also salvaged myocardium. We hypothesized that enhancement of salvaged myocardium may be due to altered extracellular volume (ECV) and contrast kinetics compared with normal and infarcted myocardium. If so, these mechanisms could contribute to overestimation of acute myocardial infarction (AMI) size.
  
  
  RESULTS
  Imaging was performed at 1.5T ≤ 7 days after AMI with serial T1 mapping and volumetric early (5 min post-contrast) and late (20 min post-contrast) gadolinium enhancement imaging. Infarcts were classified as transmural (>75% transmural extent) or non-transmural. Patients with non-transmural infarctions (n = 15) had shorter duration of symptoms before reperfusion (P = 0.02), lower peak troponin (P = 0.008), and less microvascular obstruction (P < 0.001) than patients with transmural infarcts (n = 22). The size of enhancement at 5 min was greater than at 20 min (18.7 ± 12.7 vs. 12.1 ± 7.0%, P = 0.003) in non-transmural infarctions, but similar in transmural infarctions (23.0 ± 10.0 vs. 21.9 ± 9.9%, P = 0.21). ECV of salvaged myocardium was greater than normal (39.5 ± 5.8 vs. 24.1 ± 3.1%) but less than infarcted myocardium (50.5 ± 6.0%, both P < 0.001). In kinetic studies of non-transmural infarctions, salvaged and infarcted myocardium had similar T1 at 4 min but different T1 at 8-20 min post-contrast.
  
  
  CONCLUSIONS
  The extent of gadolinium enhancement in AMI is modulated by ECV and contrast kinetics. Image acquisition too early after contrast administration resulted in overestimation of infarct size in non-transmural infarctions due to enhancement of salvaged myocardium.
authors.affiliation: Laboratory for Advanced Cardiovascular Imaging, National Heart, Lung, and Blood Institute, Department of Health and Human Services, National Institutes of Health, Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA Department of Medicine B, The Heart Center, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Sophia
authors.initials: S
authors.lastname: Hammer-Hansen
authors.affiliation: Laboratory for Advanced Cardiovascular Imaging, National Heart, Lung, and Blood Institute, Department of Health and Human Services, National Institutes of Health, Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: W Patricia
authors.initials: WP
authors.lastname: Bandettini
authors.affiliation: Laboratory for Advanced Cardiovascular Imaging, National Heart, Lung, and Blood Institute, Department of Health and Human Services, National Institutes of Health, Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: Li-Yueh
authors.initials: LY
authors.lastname: Hsu
authors.affiliation: Laboratory for Advanced Cardiovascular Imaging, National Heart, Lung, and Blood Institute, Department of Health and Human Services, National Institutes of Health, Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA Department of Medicine and Radiology, Division of Cardiovascular Medicine, University of Kentucky, Lexington, KY, USA.
authors.forename: Steve W
authors.initials: SW
authors.lastname: Leung
authors.affiliation: Laboratory for Advanced Cardiovascular Imaging, National Heart, Lung, and Blood Institute, Department of Health and Human Services, National Institutes of Health, Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: Sujata
authors.initials: S
authors.lastname: Shanbhag
authors.affiliation: Laboratory for Advanced Cardiovascular Imaging, National Heart, Lung, and Blood Institute, Department of Health and Human Services, National Institutes of Health, Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Mancini
authors.affiliation: Laboratory for Advanced Cardiovascular Imaging, National Heart, Lung, and Blood Institute, Department of Health and Human Services, National Institutes of Health, Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: Anders M
authors.initials: AM
authors.lastname: Greve
authors.affiliation: Department of Medicine B, The Heart Center, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Køber
authors.affiliation: Department of Medicine B, The Heart Center, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Jens Jakob
authors.initials: JJ
authors.lastname: Thune
authors.affiliation: Laboratory for Advanced Cardiovascular Imaging, National Heart, Lung, and Blood Institute, Department of Health and Human Services, National Institutes of Health, Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Kellman
authors.affiliation: Laboratory for Advanced Cardiovascular Imaging, National Heart, Lung, and Blood Institute, Department of Health and Human Services, National Institutes of Health, Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA araia@nih.gov.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Arai
mesh_terms: D000368:Aged; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000145:classification / Q000175:diagnosis* / Q000628:therapy; D018579:Patient Selection; D011237:Predictive Value of Tests; D018570:Risk Assessment; D012307:Risk Factors; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA
keywords: acute myocardial infarction; cardiovascular magnetic resonance imaging; extracellular volume; gadolinium enhancement; gadolinium kinetics