- Oral presentation
- Open Access
Reperfusion hemorrhage following PCI – quantification with T2* imaging and impact on area at risk assessment
© O'Regan et al; licensee BioMed Central Ltd. 2009
- Published: 28 January 2009
- Percutaneous Primary Coronary Intervention
- Microvascular Obstruction
- Late Enhancement
- Myocardial Edema
- Myocardial Salvage
Occlusion of a coronary artery leads to myocardial tissue edema in the vascular bed downstream of the vessel. The extent of hyperintense edema on T2-weighted images allows the area at risk (AAR) from ischemic injury to be retrospectively determined. However, reperfusion of severely ischemic myocardium also leads to interstitial hemorrhage and this may be an important marker for irreversible microvascular damage.
We assessed the feasibility of using T2* mapping to quantify regions of myocardial hemorrhage following percutaneous primary coronary intervention (PPCI) for acute myocardial infarction. We also hypothesized that myocardial hemorrhage would lead to an underestimate of the AAR on T2-weighted imaging using conventional signal threshold criteria.
Fifteen patients who had recently undergone PPCI within the previous 7 days were imaged. Left ventricular function was assessed with conventional cine sequences. Myocardial edema was imaged with a T2-weighted STIR sequence. Myocardial haemorrhage was imaged with a black-blood multiecho T2* sequence using navigator respiratory-gating. Microvascular obstruction (MVO) and late enhancement were imaged at 1 minute and 15 minute delays respectively using a 3 dimensional inversion-recovery sequence.
The area of myocardial edema on the T2 STIR images was measured with a boundary detection tool. This was compared to a conventional signal intensity threshold method using 2, 3 and 5 standard deviations (sd) above the mean of remote normal myocardium. A salvage index was calculated as the proportion of the AAR that did not show late enhancement. T2*-mapping of the left ventricle was performed using a threshold of 20 ms to define the presence of hemorrhage.
Our findings demonstrate the feasibility of using T2* mapping to quantify myocardial hemorrhage following infarct reperfusion. Hemorrhage is frequently observed and is associated with large infarcts where MVO is present and is an indicator of poor myocardial salvage. Hemorrhage in the core of the infarct causes signal loss on T2-weighted imaging and boundary-detection is required to reliably assess the AAR.
Studies using CMR to determine the AAR and myocardial salvage should use boundary detection methods for quantification as arbitrary signal thresholds are unreliable when hemorrhage is present. Post-reperfusion hemorrhage can be assessed with T2*-mapping and may provide an imaging marker of poor myocardial salvage.
This article is published under license to BioMed Central Ltd.