Four-dimensional speckle tracking for strain imaging in mice

The prevalence of medical imaging in diagnosing structural heart diseases (SHDs) has increased the use of indices like global longitudinal strain (GLS) to assess cardiac dysfunction. However, GLS, often estimated using B-mode echocardiography, does not capture the complexity of cardiac motion and is challenged by the rapid heart motion in small animal models like mice. We hypothesize that four-dimensional (4D) ultrasound imaging with a high-frequency transducer can provide a complete spatiotemporal description of cardiac motion. In this study, following the reconstruction of a mouse-specific left ventricle (LV), the iterative closest point algorithm, we estimated 4D displacements and strains. The proposed methodology was validated against speckle-tracking-derived displacements in synthetic images. Our methodology offers a rigorous protocol to quantify spatiotemporal cardiac motion, promoting the adoption of regional strain markers in clinical settings.