Measurement of the gadopentetate dimeglumine partition coefficient in human myocardium in vivo: Normal distribution and elevation in acute and chronic infarction

PURPOSE: To establish a method for measuring the partition coefficient (λ) of gadopentetate dimeglumine in humans in vivo, evaluate the spatial and intersubject variation in the λ of normal myocardium, and compare these values on a regional basis with λ values of acute and chronic infarcted myocardium. MATERIALS AND METHODS: Twelve healthy subjects and patients with acute (n = 5) or chronic (n = 5) myocardial infarction underwent magnetic resonance imaging at 1.5 T. Look-Locker images were acquired at four short-axis levels to measure myocardial and blood longitudinal relaxation time at baseline and after a 30-40-minute infusion of gadopentetate dimeglumine. λ was calculated as ΔR1_M/ΔR1_B, where M = myocardium, and B = blood. RESULTS: The magnitude of the estimated λ in normal myocardium was uniform over the entire myocardium at 0.56 mL/g ± 0.10 (SD). The λ values in patients with acute (0.91 mL/g ± 0.11, P <.001) or chronic (λ = 0.78 mL/g ± 0.09, P <.001) infarction were significantly elevated, as compared with those in healthy subjects. A 20% elevation in λ, as compared with the mean value of a corresponding normal circumferential segment, allowed identification of chronically (sensitivity, 88%; specificity, 96%) or acutely (sensitivity, 100%; specificity, 98%) infarcted segments. CONCLUSION: Quantification of the λ in vivo allows differentiation between normal and acutely or chronically infarcted myocardium, with high sensitivity and specificity.