Extracellular volume fraction determined by equilibrium contrast-enhanced dual-energy CT as a diagnostic indicator in patients with renal masses

Purpose: This study aimed to evaluate the feasibility of equilibrium contrast-enhanced dual-energy computed tomography (DECT) compared with tumor single-energy CT (SECT) to calculate the extracellular volume (ECV) fraction for differentiation between benign and malignant renal masses. Methods: The sample included 77 patients with renal masses who underwent DECT between March 2019 and July 2021. Unenhanced and 120-kVp equivalent images were used to calculate tumor SECT-derived ECV fractions. Iodine density images were obtained from equilibrium-phase DECT for calculating DECT-derived ECV fractions. Relationships between SECT- and DECT-derived ECV fractions were examined by Pearson correlation analysis. Consistency between the SECT- and DECT-derived ECV fractions was evaluated using the intraclass correlation coefficient and Bland–Altman analyses. The discrimination performance of ECV for malignant and benign renal masses was compared using the independent sample t-test and receiver operating characteristic curve analysis. Results: The SECT- and DECT-derived ECV fractions were strongly correlated ( r = 0.756, P < 0.001). The Bland–Altman plot of the SECT- and DECT-derived ECV fractions revealed a small bias (−1.6%). The ECV fraction was significantly higher for malignant renal masses than for benign masses (SECT, P < 0.001; DECT, P < 0.001). The area under the curve of DECT-ECV and SECT-ECV was 0.948 and 0.921, respectively. The sensitivity of DECT-ECV and SECT-ECV was 93.65% and 90.48%, respectively, while the specificity was 85.71% and 85.71%, respectively. Conclusions: Our findings show good correlation between DECT-ECV and SECT-ECV. The ECV fraction determined by equilibrium contrast-enhanced DECT is a potential new imaging marker for differentiating malignant from benign renal masses.