title: Identification of chronic myocardial infarction with extracellular or intravascular contrast agents in magnetic resonance imaging.
abstract: OBJECTIVE
  To determine whether extracellular or intravascular contrast agents could detect chronic scarred myocardium in magnetic resonance imaging (MRI).
  
  
  METHODS
  Eighteen pigs underwent a 4 week ligation of 1 or 2 diagonal coronary arteries to induce chronic myocardial infarction. The hearts were then removed and perfused in a Langendorff apparatus. Eighteen hearts were divided into 2 groups. The hearts in groups I (n=9) and II (n=9) received the bolus injection of Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA, 0.05 mmol/kg) and gadolinium- based macromolecular agent (P792, 15 micromol/kg), respectively. First pass T2* MRI was acquired using a FLASH sequence. Delayed enhancement T1 MRI was acquired with an inversion recovery prepared TurboFLASH sequence.
  
  
  RESULTS
  Wash-in of both agents resulted in a sharp and dramatic T2* signal loss of scarred myocardium similar to that of normal myocardium. The magnitude and velocity of T2* signal recovery caused by wash-out of extracellular agents in normal myocardium was significantly less than that in scarred myocardium. Conversely, the T2* signal of scarred and normal myocardium recovered to plateau rapidly and simultaneously due to wash-out of intravascular agents. At the following equilibrium, extracellular agent-enhanced T1 signal intensity was significantly greater in scarred myocardium than in normal myocardium, whereas there was no significantly statistical difference in intravascular agent-enhanced T1 signal intensity between scarred and normal myocardium.
  
  
  CONCLUSIONS
  After administration of extracellular agents, wash-out T2* first-pass and delayed enhanced T1 MRI could identify scarred myocardium as a hyperenhanced region. Conversely, scarred myocardium was indistinguishable from normal myocardium during first-pass and the steady state of intravascular agents.
authors.affiliation: Institute for Biodiagnostics, National Research Council, Winnipeg, Manitoba, Canada.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Hong-yu
authors.initials: HY
authors.lastname: Liu
authors.forename: Hang
authors.initials: H
authors.lastname: Lv
authors.forename: Bo
authors.initials: B
authors.lastname: Xiang
authors.forename: Marco
authors.initials: M
authors.lastname: Gruwel
authors.forename: Boguslaw
authors.initials: B
authors.lastname: Tomanek
authors.forename: Roxanne
authors.initials: R
authors.lastname: Deslauriers
authors.forename: Gang-hong
authors.initials: GH
authors.lastname: Tian
mesh_terms: D000818:Animals; D002908:Chronic Disease; D003287:Contrast Media; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging; D009203:Myocardial Infarction / Q000473:pathology*; D009206:Myocardium / Q000473:pathology; D013552:Swine
chemical_list: D003287:Contrast Media