Clinical utility of non-gated 4-min delayed dual-energy CT for myocardial extracellular volume quantification

Objectives: To develop and validate the myocardial extracellular volume (ECV) obtained from non-electrocardiography (ECG)-gated delayed CT images acquired 4 min post-contrast infusion (4-min-non-ECG-ECV) compared with the ECV obtained from ECG-gated delayed CT images acquired 10 min post-contrast infusion (Conv-ECV). Methods: We retrospectively analysed 29 patients (males: 21) after a comprehensive CT protocol of both 4-min-non-ECG-ECV and Conv-ECV on a dual-layer CT scanner. The mean volume of contrast medium administered was 90 ± 11.8 mL, and the average heart rate during the CT examinations was 74.2 ± 18.2 bpm. Two independent observers calculated the respective 4-min-non-ECG-ECV and Conv-ECV. We determined the correlation between the ECV obtained by the 2 methods and conducted a Bland-Altman analysis to identify systematic errors and determine the limits of agreement (LOA) between the 4-min-non-ECG-ECV and Conv-ECV values. Results: The respective median ECV values for observer 1 were 27.3 for 4-min-non-ECG-ECV and 26.5 for Conv-ECV; for observer 2, they were 27.8 and 27.1. The correlation between the methods was 0.97 for both observers (P <. 01). The Bland-Altman plots for observers 1 and 2 demonstrated a minor bias (-0.2% and -0.5%, respectively), with the 95% LOA ranges at -4.4% to 4.0% and -5.0% to 4.0%, respectively. Conclusion: The 4-min-non-ECG-ECV provided ECV values comparable to those obtained by Conv-ECV. Advances in knowledge: Myocardial ECV quantification is feasible using a non-gated, 4-min delayed dual-energy CT scan with an already established CT acquisition method. This approach achieves ECV accuracy comparable to that of the conventional CT-ECV calculation method (gated 10-min delayed imaging) while enhancing clinical efficacy and diagnostic throughput.