title: Magnetic resonance imaging of haemorrhage within reperfused myocardial infarcts: possible interference with iron oxide-labelled cell tracking?
abstract: OBJECTIVE
  Magnetic resonance imaging (MRI) has been proposed as a tool to track iron oxide-labelled cells within myocardial infarction (MI). However, infarct reperfusion aggravates microvascular obstruction (MO) and causes haemorrhage. We hypothesized that haemorrhagic MI causes magnetic susceptibility-induced signal voids that may interfere with iron oxide-labelled cell detection.
  
  
  RESULTS
  Pigs (n = 23) underwent 2 h occlusion of the left circumflex artery. Cine, T2*-weighted, perfusion, and delayed enhancement MRI scans were performed at 1 and 5 weeks, followed by ex vivo high-resolution scanning. At 1 week, MO was observed in 17 out of 21 animals. Signal voids were observed on T2*-weighted scans in five out of eight animals, comprising 24 +/- 22% of the infarct area. A linear correlation was found between area of MO and signal voids (R2 = 0.87; P = 0.002). At 5 weeks, MO was observed in two out of 13 animals. Signal voids were identified in three out of seven animals. Ex vivo scanning showed signal voids on T2*-weighted scanning in all animals because of the presence of haemorrhage, as confirmed by histology. Signal voids interfered with the detection of iron oxide-labelled cells ex vivo (n = 21 injections).
  
  
  CONCLUSIONS
  Haemorrhage in reperfused MI produces MRI signal voids, which may hamper tracking of iron oxide-labelled cells.
authors.affiliation: Cardiovascular Research School Coeur, Experimental Cardiology, Thoraxcenter, Erasmus MC University Medical Center, Dr Molewaterplein 40, 3015 GD Rotterdam, The Netherlands.
authors.forename: Ewout J
authors.initials: EJ
authors.lastname: van den Bos
authors.forename: Timo
authors.initials: T
authors.lastname: Baks
authors.forename: Amber D
authors.initials: AD
authors.lastname: Moelker
authors.forename: Wendy
authors.initials: W
authors.lastname: Kerver
authors.forename: Robert-Jan
authors.initials: RJ
authors.lastname: van Geuns
authors.forename: Willem J
authors.initials: WJ
authors.lastname: van der Giessen
authors.forename: Dirk J
authors.initials: DJ
authors.lastname: Duncker
authors.forename: Piotr A
authors.initials: PA
authors.lastname: Wielopolski
mesh_terms: D000818:Animals; D003287:Contrast Media; D005290:Ferric Compounds; D006470:Hemorrhage / Q000175:diagnosis*; D018810:Magnetic Resonance Angiography / Q000592:standards*; D008833:Microcirculation; D009203:Myocardial Infarction / Q000473:pathology / Q000628:therapy*; D015425:Myocardial Reperfusion / Q000009:adverse effects*; D013552:Swine
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide