A fast and reproducible method to estimate left atrial volume using cardiac computed tomography

•Based on either area or diameter values, methods to assess left atrium volume on plain or unenhanced cardiac CT are accurate and reproducible.•These simple methods on orthogonal and axial planes provide better results than the biplane measurement normally used with echocardiography and cardiac MRI.•In routine, these methods represent a valid alternative to the simple maximal axial left atrium area estimate, and to the more sophisticated direct volumetric method, which requires more time and specific software. The purpose of this study was to do better than the simple maximal axial area (MAreaax) and to validate simple, fast and robust orthogonal methods for determining the left atrium volume (LAV) with cardiac CT (CCT). A total of 60 patients who underwent CTT were retrospectively included. There were 30 men and 30 women with a mean age of 59±12 (SD) years (range: 27–80 years), using four methods to assess LAV beyond the MAreaax: two orthogonal methods requiring the measurements of axial, coronal and sagittal planes of 3 diameters LAV3diam or 3 area LAV3Areas; Area-length biplane method LAVbiplane; and volumetric method LAVvolumetric using a semi-automated tool that served as the reference standard. The orthogonal methods were applied on contrast-enhanced (IV+) and unenhanced (IV-) CCT images. Comparisons were performed using Pearson correlation test (r) and Bland-Altman analysis. Inter- and intra-observer variability were assessed using intraclass correlation coefficient (ICC) with a two-way mixed-effects model. On IV+ CCT, LAVbiplane, LAV3diam-IV+, LAV3Areas-IV+ underestimated LAV (-15±1.99mL; -21±1.37mL; -15±1.98mL; all P