Aims: 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. Methods and 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 (R 2 = 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). Conclusion: Haemorrhage in reperfused MI produces MRI signal voids, which may hamper tracking of iron oxide-labelled cells.

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European Heart Journal
Department of Cardiology

van den Bos, E.J, Baks, T, Moelker, A.D, Kerver, W, van Geuns, R.J.M, van der Giessen, W.J, … Wielopolski, P.A. (2006). Magnetic resonance imaging of haemorrhage within reperfused myocardial infarcts: Possible interference with iron oxide-labelled cell tracking?. European Heart Journal, 27(13), 1620–1626. doi:10.1093/eurheartj/ehl059