Improved visualization of endocardial borders with Short-Lag Spatial Coherence imaging of fundamental and harmonic ultrasound data

Abstract

Endocardial border visualization, a common task in echochardiography, is typically challenged by the presence of acoustic clutter. This study investigates endocardial border visibility in co-registered fundamental and harmonic data when utilizing the Short-Lag Spatial Coherence (SLSC) beamformer, a clutter reduction approach that we developed. Individual channel echo data were acquired from the left ventricle of 12 volunteers, after informed consent and IRB approval, to create matched image quadruplets of fundamental and harmonic B-mode and SLSC images. Contrast-to-noise ratios (CNR) were measured, and three cardiologists rated the visibility of endocardial segments in randomly ordered cine loops. The statistical significance of visibility ratings was determined with a Holm-Bonferroni correction at a significance level, α = 0.05. CNR increased approximately twofold in fundamental and harmonic SLSC images compared to fundamental and harmonic B-mode images. Fundamental and Harmonic SLSC imaging offered the greatest benefits when fundamental B-mode image quality was poor. Improvements in endocardial segment visibility in short-axis views ranged from 1628% (α = 0.05) compared to fundamental B-mode images, while improvements in the apical four chamber views ranged from 2235% (α = 0.05) compared to fundamental and harmonic B-mode images. Results suggest that SLSC and HSCI have the potential to increase endocardial border visualization and thereby improve cardiac assessments of poor-quality B-mode images.