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Reperfused myocardial infarctions on T1- and susceptibility-enhanced MRI: evidence for loss of compartmentalization of contrast media.

4 Saeed M, Wendland MF, Masui T, Higgins CB.

Assessment of myocardial salvage after ischemia and reperfusion using magnetic resonance imaging and spectroscopy.

3 Wolfe CL, Moseley ME, Wikstrom MG, Sievers RE, Wendland MR, Dupon JW, Finkbeiner WE, Lipton MJ, Parmley WW, Brasch RC.

Physiological basis of myocardial contrast enhancement in fast magnetic resonance images of 2-day-old reperfused canine infarcts.

2 Judd RM, Lugo-Olivieri CH, Arai M, Kondo T, Croisille P, Lima JAC, Mohan V, Becker LC, Zerhouni EA.

Regional heterogeneity of human myocardial infarcts demonstrated by contrast-enhanced MRI: potential mechanisms.

1 Lima JAC, Judd RM, Bazille A, Schulman SP, Atalar E, Zerhouni EA.

These regional differences in time constants also indicate the extent and severity of myocardial injury.

The extent of regions with abnormal time constants correlated well with triphenyltetrazolium chloride–determined infarct size ( r=.94, y=0.95 x+4.17, P<.001).Ĭonclusions In contrast-enhanced magnetic resonance images of acute, reperfused rabbit infarcts, differential image intensity is primarily due to regional differences in contrast agent wash-in and washout time constants. In addition, spatial maps of washout time constants were produced. Microsphere flows in the infarct rim and core were 42.9±4.0% and 12.0☑.6% of normal myocardium and correlated well with washout time constants ( r=.86, y=0.77 x−0.002, P<.001), suggesting that these time constants index the severity of microvascular damage. There were marked differences in Gd-DTPA wash-in and washout time constants (wash-in, 0.8☐.1, 2.1☐.2, and 16.3☒.4 minutes, P<.001 washout, 1.6☐.1, 4.8☐.5, and 31.1☓.3 minutes, P<.001) in normal, infarct rim, and infarct core regions, respectively, resulting in differential enhancement of these regions. Regional blood flow was also measured by use of radioactive microspheres in all rabbits. T1-weighted spin-echo images were acquired continuously during step changes in perfusate Gd-DTPA concentration. Methods and Results Thirteen rabbits underwent in situ coronary artery occlusion and reperfusion followed by isolated perfusion with cardioplegic solution. This study was designed to evaluate possible mechanisms and to relate altered enhancement patterns to myocardial perfusion and viability. The precise mechanisms that lead to these altered enhancement patterns are unknown. Customer Service and Ordering Informationīackground Contrast medium–enhanced magnetic resonance images of acute, reperfused infarcts have shown hypoenhanced and hyperenhanced regions in areas of injured myocardium.Stroke: Vascular and Interventional Neurology.

Journal of the American Heart Association (JAHA).

Circ: Cardiovascular Quality & Outcomes.

Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB).