Magnetic resonance imaging of haemorrhage within reperfused myocardial infarcts: possible interference with iron oxide-labelled cell tracking?
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.
van den Bos
Ewout J
EJ
Cardiovascular Research School Coeur, Experimental Cardiology, Thoraxcenter, Erasmus MC University Medical Center, Dr Molewaterplein 40, 3015 GD Rotterdam, The Netherlands.
Baks
Timo
T
Moelker
Amber D
AD
Kerver
Wendy
W
van Geuns
Robert-Jan
RJ
van der Giessen
Willem J
WJ
Duncker
Dirk J
DJ
Wielopolski
Piotr A
PA
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
D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide