Gadolinium Pharmacokinetics of Chronic Myocardial Infarcts: Implications for Late Gadolinium-Enhanced Infarct Imaging

Purpose: To monitor gadohnium pharmacokinetics in the hearts of patients with chronic myocardial infarcts and to determine the variability of contrast agent concentrations and accuracy of infarct detection over an hour time period. Materials and Methods: Twenty-five patients with chronic myocardial infarcts were examined. T1 measurements were performed every 2 minutes using an inversion recovery CINE balanced steady-state free precession technique. Paired differences in T1 values over time for the discrimination between the left ventricular (LV) bloodpool, viable, and infarct myocardium were statistically evaluated. The average change per 1, 5, and 10 minutes of the inversion time parameter for optimal nulling of viable myocardium was calculated. Receiver operator characteristic (ROC) curve analysis was performed to compare the performance of late gadolinium-enhanced infarct imaging at increasing delays after contrast agent administration. Results: Significantly different T1 values were reached after 10 minutes between the LV bloodpool, infarcted, and viable myocardium. The T1 difference between myocardial infarcts and the LV bloodpool increased over time, while the difference between viable myocardium and the LV bloodpool decreased. ROC curve analysis showed a decrease in performance of a fixed T1 value to discriminate between the LV bloodpool and viable myocardium over time, while there was a marked increase in the discrimination between the LV bloodpool and infarcted myocardium. Conclusion: The ability to discriminate between infarcted myocardium and the LV bloodpool improves with an increasing delay after contrast agent administration while discrimination between viable myocardium and the LV bloodpool decreases.