Monitoring of Monocyte Recruitment in Reperfused Myocardial Infarction with Intramyocardial Hemorrhage and Microvascular Obstruction by Combined Fluorine-19 and Proton Cardiac MRI
Background—Monocytes and macrophages are indispensable in the healing process of myocardial infarction (MI). However, the spatiotemporal distribution of monocyte infiltration and its correlation to prognostic indicators of reperfused MI have not been well described.
Methods and Results—With combined fluorine-19/proton-MRI (19F/1H-MRI), we non-invasively visualized the spatiotemporal recruitment of monocytes in vivo in a rat model of reperfused MI. Blood monocytes were labeled by intravenous injection of 19F-perfluorocarbon (PFC) emulsion one day post-MI. The distribution patterns of monocyte infiltration were correlated to the presence of microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH). In vivo 19F/1H-MRI performed in series revealed that monocyte infiltration was spatially inhomogeneous in reperfused MI areas. In absence of MVO, monocyte infiltration was more intense in MI regions with serious ischemia-reperfusion injuries indicated by severe IMH. However, monocyte recruitment was significantly impaired in MVO areas, which was accompanied by severe IMH. Compared to MI with isolated IMH, MI with MVO resulted in significantly worse pump function of left ventricle (LV) 28 days post-MI.
Conclusions—Monocyte recruitment was inhomogeneous in reperfused MI tissue. It was highly reduced in MVO areas defined by MRI. The impaired monocyte infiltration in MVO regions might be related to delayed healing and worse functional outcomes in the long term. Therefore, monocyte recruitment in MI with MVO could be a potential diagnostic and therapeutic target monitored non-invasively and longitudinally by 19F/1H-MRI in vivo.
- microvascular obstruction
- myocardial infarction
- magnetic resonance imaging
- Received February 20, 2013.
- Revision received July 6, 2013.
- Accepted August 5, 2013.