Evaluation of extracellular volume fraction thresholds corresponding to myocardial late-gadolinium enhancement using cardiac magnetic resonance.

To establish extracellular volume fraction (ECV) thresholds corresponding to myocardial lesion detected by late-gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) imaging. Fifty-six patients with myocardial infarction or hypertrophic cardiomyopathy underwent LGE, pre- and post-contrast modified Look-Locker inversion recovery (MOLLI) sequences on a 3-T CMR system. Short-axis MOLLI images generated ECV maps of left ventricular (LV) walls. The LGE areas were semi-automatically determined by different signal threshold techniques. The areas of elevated ECV were measured using ECV thresholds of 28-48%. The LGE areas were compared with the areas of elevated ECV at the corresponding LV levels. The myocardial areas of LGE and elevated ECVs showed a strong and positive correlation (P < 0.01). The LGE threshold, set at two standard deviations above the mean signal from the remote myocardium, corresponded well with the area of ECV >32%. When using the full width at half-maximum (FWHM) technique, the LGE area corresponded well with the area of ECV >42 or 44%. By applying particular ECV thresholds, myocardial ECV maps can define myocardial status equivalent to LGE, and definite ECV thresholds may be useful for the straightforward evaluation of myocardial phenotypes.