title: Postreperfusion myocardial technetium-99m-sestamibi defect corresponds to area at risk: experimental results from an ischemia-reperfusion porcine model.
abstract: BACKGROUND
  Technetium-99m-sestamibi (MIBI) is the most frequently used myocardial perfusion tracer in patients with ischemic heart disease. In patients with acute ST-elevation myocardial infarction, we previously found that the defect in myocardial MIBI uptake was the same in patients injected with MIBI before primary angioplasty and in patients injected immediately after successful treatment. Thus, reperfusion may not be followed by increased uptake of MIBI. Instead, the MIBI defect after reperfusion may reflect the area at risk (AAR) defined by MIBI injected before treatment. We intended to investigate whether myocardial imaging with MIBI administered after reperfusion reflects myocardial perfusion or rather the ischemic AAR.
  
  
  METHODS
  In 12 pigs, left anterior descending coronary artery was totally occluded for 45 min with an angioplasty balloon. After a 2-h reperfusion, MIBI was injected intravenously, and (153)Gd-microspheres were injected in left atrium. AAR and infarct size (IS) were determined by histochemical staining. MIBI and microsphere distribution were evaluated by counting the sliced left ventricle on a gamma camera. Defects were defined as uptake less than 45% of maximum uptake.
  
  
  RESULTS
  The mean±S.D. defect size as a fraction of left ventricle was for MIBI 21%±5.5%, AAR 25%±6.3%, IS 13%±3.9% and microspheres defect size 7.3%±5.5%. MIBI defect size overestimated IS (P=.0005) and microspheres defect size (P=.0001), but it was not significantly different from AAR (P=.30).
  
  
  CONCLUSIONS
  In a porcine model of myocardial infarction after 45 min of ischemia, MIBI administered 120 min after reperfusion delineates AAR.
authors.affiliation: Clinical Institute, Aarhus University, DK-8000 Aarhus C, Denmark. runa.poulsen@ki.au.dk
authors.forename: Runa Hyldgaard
authors.initials: RH
authors.lastname: Poulsen
authors.forename: Hans Erik
authors.initials: HE
authors.lastname: Bøtker
authors.forename: Michael
authors.initials: M
authors.lastname: Rehling
mesh_terms: D000818:Animals; D016477:Artifacts; D001692:Biological Transport; D004195:Disease Models, Animal; D005260:Female; D008863:Microspheres; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D015424:Reperfusion / Q000009:adverse effects*; D015427:Reperfusion Injury / Q000000981:diagnostic imaging* / Q000378:metabolism; D015203:Reproducibility of Results; D012306:Risk; D013552:Swine; D017256:Technetium Tc 99m Sestamibi / Q000737:chemistry / Q000378:metabolism
chemical_list: D017256:Technetium Tc 99m Sestamibi