title: Temporal and spatial characteristics of the area at risk investigated using computed tomography and T1-weighted magnetic resonance imaging.
abstract: OBJECTIVE
  Cardiovascular magnetic resonance (CMR) imaging can measure the myocardial area at risk (AAR), but the technique has received criticism for inadequate validation. CMR commonly depicts an AAR that is wider than the infarct, which in turn would require a lateral perfusion gradient within the AAR. We investigated the presence of a lateral perfusion gradient within the AAR and validated CMR measures of AAR against three independent reference standards of high quality.
  
  
  RESULTS
  Computed tomography (CT) perfusion imaging, microsphere blood flow analysis, T1-weighted 3T CMR and fluorescent microparticle pathology were used to investigate the AAR in a canine model (n = 10) of ischaemia and reperfusion. AAR size by CMR correlated well with CT (R(2) = 0.80), microsphere blood flow (R(2) = 0.80), and pathology (R(2) = 0.74) with good limits of agreement [-0.79 ± 4.02% of the left ventricular mass (LVM) vs. CT; -1.49 ± 4.04% LVM vs. blood flow and -1.01 ± 4.18% LVM vs. pathology]. The lateral portion of the AAR had higher perfusion than the core of the AAR by CT perfusion imaging (40.7 ± 11.8 vs. 25.2 ± 17.7 Hounsfield units, P = 0.0008) and microsphere blood flow (0.11 ± 0.04 vs. 0.05 ± 0.02 mL/g/min, lateral vs. core, P = 0.001). The transmural extent of MI was lower in the lateral portion of the AAR than the core (28.2 ± 10.2 vs. 17.4 ± 8.4% of the wall, P = 0.001).
  
  
  CONCLUSIONS
  T1-weighted CMR accurately quantifies size of the AAR with excellent agreement compared with three independent reference standards. A lateral perfusion gradient results in lower transmural extent of infarction at the edges of the AAR compared with the core.
authors.affiliation: National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: Jesper
authors.initials: J
authors.lastname: van der Pals
authors.affiliation: National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: Sophia
authors.initials: S
authors.lastname: Hammer-Hansen
authors.affiliation: National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: Sonia
authors.initials: S
authors.lastname: Nielles-Vallespin
authors.affiliation: National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), 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: National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: Joni
authors.initials: J
authors.lastname: Taylor
authors.affiliation: National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: Shawn
authors.initials: S
authors.lastname: Kozlov
authors.affiliation: National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), 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: National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), Building 10, Room B1D416, MSC 1061, 10 Center Drive, Bethesda, MD 20892-1061, USA.
authors.forename: Marcus Y
authors.initials: MY
authors.lastname: Chen
authors.affiliation: National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), 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: D000818:Animals; D003287:Contrast Media; D004195:Disease Models, Animal; D004285:Dogs; D005434:Flow Cytometry; D007091:Image Processing, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008863:Microspheres; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000000981:diagnostic imaging; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: CT; MRI; area at risk; myocardial infarction; myocardial ischaemia; myocardial perfusion