• Yuesong Yang, Warren D Foltz, John J Graham, Jay S Detsky, Alexander J Dick, and Graham A Wright.
• Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada. ysyang@sri.utoronto.ca
• J Magn Reson Imaging. 2007 Dec 1; 26 (6): 1486-92.

PurposeTo investigate a T1 and T2 preparation pulse sequence to evaluate microvascular obstruction (MO) in a porcine model of reperfused acute myocardial infarction (AMI).Materials And MethodsA total of 14 pigs with reperfused AMI underwent MRI examinations at baseline and three to four hours after reperfusion. MRI scans included a left ventricular functional study, T1 and T2 measurement on a 1.5T MRI system. At reperfusion, first-pass myocardial perfusion (FPMP) images were obtained after bolus injection of gadopentetate dimeglumine followed by an intravenous drip. Delayed contrast-enhanced MRI (DE-MRI) and T1 measurements were performed 30 and 45 minutes, respectively, after the bolus, during a constant infusion of gadopentetate dimeglumine.ResultsIn 11 pigs MO was hypoenhanced in FPMP and DE-MRI. In later T1 preparation difference images postcontrast, MO was hyperenhanced while delayed hyperenhanced (DHE) regions appeared dark. MO areas on DE-MRI and T1 images were comparable. T1 reduction (%) postcontrast in MO was small compared to measurements from DHE regions (P < 0.0001) and similar to those from control segments (P = 0.66). Precontrast T1 and T2 values at reperfusion from MO and DHE regions were larger than in control regions.ConclusionUsing T1 preparation under a constant gadopentetate dimeglumine (Gd-DTPA) infusion, delayed imaging at 30 to 45 minutes demonstrates MO as a positive contrast with larger T1 values. Elevated T1 and T2 values in MO precontrast may also help to differentiate them from both control and DHE regions.(c) 2007 Wiley-Liss, Inc.

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