Cardiac Imaging Identifies Edema Early After Ischemia

MRI can identify ischemia before irreversible injury takes place

THURSDAY, April 2 (HealthDay News) -- T2-weighted cardiac imaging can identify edema early after myocardial ischemia in dogs before irreversible injury has occurred, according to a study in the April 7 issue of the Journal of the American College of Cardiology.

Hassan Abdel-Aty, M.D., from the Libin Cardiovascular Institute of Alberta in Calgary, Canada, and colleagues examined whether imaging myocardial edema by state-of-the-art 1.5-T MRI could be used for earlier identification of acute myocardial ischemia in 15 dogs induced to develop ischemia by transient coronary occlusion.

The researchers found that after a mean of 28 minutes after inducing ischemia, there was an area of high T2-weighted signaling intensity that matched areas of new akinesia. The contrast-to-noise ratio between the ischemic and remote myocardium increased at this time from a mean of 1.0 to 12.8 and further increased to a mean of 15.8 after reperfusion. Myocardial water content was significantly higher in the ischemic areas and correlated with the T2 contrast-to-noise ratio. Myocardial late gadolinium enhancement (indicating necrosis, i.e., irreversible myocyte injury) and troponin elevation (a marker of myocardial injury) were not observed at this time, the report indicates.

"We provide the first evidence that T2-weighted cardiovascular MRI of edema detects acute ischemic myocyte injury before the onset of irreversible injury," Abdel-Aty and colleagues conclude. "T2-weighted cardiovascular MRI may serve as a very useful diagnostic marker in clinical settings such as unstable angina or evolving infarction."

Abdel-Aty received an educational grant from Siemens Medical Solutions, which makes the imaging system used in the study.

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