Feasibility of the single-bolus strategy for measuring the partition coefficient of Gd-DTPA in patients with myocardial infarction: Independence of image delay time and maturity of scar

The partition coefficient of Gd-DTPA (lambda) is elevated in infarcted relative to normal myocardium. Although MRI following an infusion of Gd-DTPA allows for the quantification of X, infarct imaging is more routinely performed using a bolus. In this study we sought to determine how image delay time and time postinfarction influence the estimation of X by the bolus strategy. Both infusion and bolus imaging were performed twice in the same group of patients (N = 9): once at 3-4 weeks and again 6 months after reperfusion therapy for myocardial infarction (MI). Bolus estimates of X were compared with those calculated after 60 min infusion, and comparisons were repeated at 6 months. The X of infarcted myocardium was significantly greater than that of normal tissue, irrespective of either the technique used or the time postinfarction (P < 0.0001, for each). The concordance (R.) between bolus and infusion estimates of lambda was > 0.83 for all image delays > 4 min postinjection, and R-c at 2 min (0.78 +/- 0.04) was significantly less than R-c determined for longer image delay times (P = 0.009). R-c did not change with time postinfarction (P = 0.604). Thus, the bolus strategy can be used to provide estimates of lambda that are stable from 1-6 months postinfarction and independent of image delay time.