Reperfused myocardial infarction: Contrast-enhanced 64-section CT in comparison to MR imaging

Purpose: To prospectively compare 64-section multidetector computed tomography (CT) and cardiac magnetic resonance (MR) imaging for the early assessment of myocardial enhancement and infarct size after acute reperfused myocardial infarction (MI). Materials and Methods: The study was HIPAA compliant and was approved by the institutional review board. All participants gave written informed consent. Twenty-one patients (18 men; mean age, 60 years ± 13 [standard deviation]) were examined with 64-section multidetector CT and cardiac MR imaging 5 days or fewer after a first reperfused MI. Multidetector CT was performed during the first pass of contrast material to assess myocardial perfusion and detect microvascular obstruction (no reflow). In 15 patients, a second scan was performed 7 minutes later to assess total infarct size by using delayed hyperenhancement. Early hypoenhancement and delayed hyperenhancement were compared between multidetector CT and cardiac MR imaging with Pearson correlation coefficient and Bland-Altman analysis. Results: Early hypoenhancement was recognized on all multidetector CT and cardiac MR images. Delayed hyperenhancement was observed with cardiac MR imaging at all examinations and with multidetector CT at 11 of 15 examinations. While signal intensity differences between hypoperfused and normal myocardium were comparable for first-pass multidetector CT and cardiac MR imaging, cardiac MR imaging had a far better contrast-to-noise ratio (CNR) for delayed acquisitions than did CT (P < .001). Hypoenhanced areas (as a percentage of left ventricular mass) at first-pass multidetector CT (11% ± 6) correlated well with those at first-pass cardiac MR imaging (7% ± 4, R² = 0.72). Delayed-enhancement multidetector CT (13% ± 9) correlated well with delayed-enhancement cardiac MR imaging (15% ± 7, R² = 0.55). Quantification of delayed hypoenhancement (n = 12) had very good correlation between multidetector CT (4% ± 4) and cardiac MR imaging (3% ± 2) (R² = 0.85). Conclusion: Early and late hypoenhancement showed good CNR and correlated well between multidetector CT and cardiac MR imaging.