Measurement of Myocardial Extracellular Volume Fraction FromIodine Density Images Using Single-Source, Dual-Energy Computed Tomography: A Feasibility Study

Objective: The aims of this study were to develop and validate an iodine density method for the quantification of myocardial extracellular volume (ECV) fraction using single-source, dual-energy computed tomography. Methods: Extracellular volume measurements were carried out in 40 subjects (20 patients with heart failure, 20 control subjects) using single-source, dual-energy computed tomography. Subtraction-derived ECVs (subECVs) were computed by subtracting precontrast from delayed images. Iodine density-derived ECVs (iECVs) were calculated from iodine density images obtained from delayed images. Iodine density-derived ECVs were compared with reference subECVs. Results: A strong correlation (r = 0.896, P < 0.0001) and a small bias (-0.06%) were determined between subECVand iECV with high interobserver concordances (0.915 and 0.906, respectively). Extracellular volume measurements in patients with heart failure were higher in both subECV and iECV compared with control subjects (34.6% [SD, 5.0%] vs 29.5% [SD, 3.6%], P = 0.001, for subECV; 34.9% [SD, 4.5%] vs 29.2% [SD, 2.6%], P < 0.0001, for iECV). Conclusions: Extracellular volume analysis using iodine density is a useful tool for the noninvasive quantification of ECV in myocardial diseases.