title: Myocardium at risk can be determined by ex vivo T2-weighted magnetic resonance imaging even in the presence of gadolinium: comparison to myocardial perfusion single photon emission computed tomography.
abstract: OBJECTIVE
  Determination of the myocardium at risk (MaR) and final infarct size by cardiac magnetic resonance imaging (CMR) enables calculation of salvaged myocardium in acute infarction. T2-weighted imaging is performed prior to the administration of gadolinium, since gadolinium affects T2 tissue properties. This is, however, difficult in an ex vivo model since gadolinium must be administered for determination of infarct size by CMR. We aimed to test the ability of ex vivo T2-weighted imaging to assess MaR using myocardial perfusion single photon emission computed tomography (SPECT) as reference and to investigate whether MaR could be assessed by ex vivo T2-weighted imaging after injection of gadolinium.  Materials and methods In 18 domestic pigs, the left anterior descending artery was occluded for either 30 or 40 min, followed by 4 h of reperfusion. After explantation of the hearts, myocardial perfusion SPECT and T2-weighted imaging were performed for determination of MaR, either with or without gadolinium. Infarct size was determined by T1-weighted imaging and by triphenyl tetrazolium chloride (TTC) staining.
  
  
  RESULTS
  T2-weighted imaging agreed with myocardial perfusion SPECT, both with and without gadolinium (r(2)= 0.70, P < 0.01) with a bias of 2.6 ± 5.1% (P = 0.04). Infarct size was 15.4 ± 5.3 and 22.1 ± 5.6% with TTC and T1-weighted imaging, respectively (P = 0.008) in nine pigs who had both infarct measures.
  
  
  CONCLUSIONS
  T2-weighted CMR imaging can be used to determine MaR in an ex vivo experimental model, both with and without the presence of gadolinium. Thus, CMR alone can be used to assess myocardial salvage in experimental studies.
authors: Department of Clinical Physiology, Skåne University Hospital and Lund University, Lund, Sweden.
authors: Joey F A
authors: JF
authors: Ubachs
authors: Henrik
authors: H
authors: Engblom
authors: Sasha
authors: S
authors: Koul
authors: Mikael
authors: M
authors: Kanski
authors: Patrik
authors: P
authors: Andersson
authors: Jesper
authors: J
authors: van der Pals
authors: Marcus
authors: M
authors: Carlsson
authors: David
authors: D
authors: Erlinge
authors: Håkan
authors: H
authors: Arheden
mesh_terms: D000465:Algorithms; D000818:Animals; D003287:Contrast Media; D005682:Gadolinium; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012984:Software; D013552:Swine; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D003287:Contrast Media; D005682:Gadolinium