Abstract 253: Arterial Spin Labeling MRI Quantifies the Recovery of Myocardial Perfusion During Infarct Healing in Mice
Introduction: Experimental myocardial infarction (MI) and knockout mice are used to study the roles of individual genes in MI and post-MI left ventricular (LV) remodeling. Arterial spin labeling (ASL) MRI enables the quantification of myocardial perfusion (MP), but is sensitive to variable heart rates and erratic respiratory patterns, prohibiting accurate measurement early after MI. We developed a cardio-respiratory gated (CRG) ASL method that is insensitive to these factors in order to measure MP in mice.
Methods: CRG-ASL was developed on a 7T MR system. Reperfused MI was induced in 7 mice via 1 hour coronary occlusion. MRI was performed at baseline (BSL) and at 1, 7, & 14 days post-MI. In addition to ASL, cine MRI assessed LV structure and function, and late gadolinium-enhancement (LGE) quantified infarct size.
Results: At BSL, MP by ASL was 4.9±0.5 ml/g·min. Infarct size by LGE was 43.4±3.7% of LV mass. MP in the infarct zone decreased to 0.9±0.8 ml/g·min 1 day post-MI, and partially recovered to 2.8±0.6 and 3.5±0.4 ml/g·min on days 7 and 14 post-MI (Fig⇓). Increased LV volumes and decreased function were seen by day 14 (Table⇓).
Conclusion: CRG-ASL quantifies regional changes in MP after MI. These changes likely reflect neovascularization during infarct healing. This method, when applied to genetically-engineered mice, may elucidate the roles of individual genes in post-MI neovascularization.
This research has received full or partial funding support from the American Heart Association, Mid-Atlantic Affiliate (Maryland, North Carolina, South Carolina, Virginia & Washington, DC).