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Noninvasive measurements of infarct size after thrombolysis with a necrosis-avid MRI contrast agent
1Departments of Cardiology and Radiology, University Hospitals Leuven, Belgium.
Background:
Gadophrin-2 is a new MRI contrast agent with high affinity for necrotic myocardium. The aim of the study was to evaluate whether noninvasive measurements of infarct size after thrombolysis are possible with gadophrin-2-enhanced MRI.
Methods And Results:
Coronary artery thrombosis was induced in 3 groups of dogs by the copper-coil technique. Thrombolytic therapy together with aspirin and heparin was initiated after 90 minutes of occlusion. One day (group A), 2 days (group B), or 6 days (group C) after infarction, gadophrin-2 was injected intravenously (50 micromol. kg-1). In vivo T1-weighted segmented turbo-FLASH, in vivo T2-weighted segmented half-Fourier turbo spin echo (HASTE), and T1- and T2-weighted spin-echo MRI of the excised heart were performed 24 hours after gadophrin-2 injection. Regions of strong enhancement were observed on T1-weighted images. Planimetry of short-axis MR images and of corresponding triphenyltetrazolium chloride (TTC)-stained left ventricular (LV) slices showed a close correlation between the enhanced areas and TTC-negative areas for both in vivo (r2=0.98, P<0.0001; mean difference, 0.9+/-2.0% [SD] of the LV volume [LVV]) and postmortem (r2=0.99, P<0.0001; mean difference, 0.9+/-1.4% of LVV) measurements. T2-weighted images overestimated the infarct size by 8.1+/-5.4% of LVV. The mean infarct size was 10.8+/-11.6% of LVV (group A), 22.4+/-11.7% (group B), and 5.1+/-9.3% (group C).
Conclusions:
In this animal model, in vivo gadophrin-2-enhanced MRI could precisely determine infarct size after thrombolytic therapy. This technique may be very useful for the noninvasive evaluation of infarct size after reperfusion for AMI.
Insights
Gadophrin-2 enhanced MRI accurately measured infarct size in a canine model after thrombolysis. This noninvasive technique shows promise for evaluating myocardial infarction (MI) size post-reperfusion.
Area of Science:
- Cardiovascular Imaging
- Medical Diagnostics
- Pharmacology
Background:
- Gadophrin-2 is a novel MRI contrast agent with high affinity for necrotic myocardium.
- Assessing infarct size noninvasively after thrombolysis is crucial for patient management.
Purpose of the Study:
- To evaluate the efficacy of gadophrin-2-enhanced MRI for noninvasive infarct size measurement after thrombolytic therapy.
- To correlate MRI-derived infarct size with histopathological findings.
Main Methods:
- Coronary artery thrombosis induced in dogs, followed by thrombolytic therapy.
- Gadophrin-2 administered intravenously at different time points post-infarction.
- In vivo and ex vivo MRI (T1-weighted, T2-weighted) performed 24 hours post-contrast.
- Comparison with triphenyltetrazolium chloride (TTC)-stained myocardial slices.
Main Results:
- Strong contrast enhancement observed on T1-weighted MRI correlated closely with TTC-negative infarct areas.
- In vivo measurements showed high correlation (r2=0.98) and minimal difference (0.9+/-2.0% LVV) compared to postmortem analysis.
- T2-weighted images overestimated infarct size, while T1-weighted images provided precise quantification.
Conclusions:
- Gadophrin-2-enhanced MRI precisely determined infarct size in an animal model post-thrombolysis.
- This noninvasive MRI technique holds significant potential for evaluating myocardial infarction size after reperfusion therapy for acute myocardial infarction (AMI).