Speckletracking

Speckle-tracking, also known as speckle-tracking echocardiography in its most common form, is an imaging analysis technique that uses natural acoustic markers, or speckles, within ultrasound images to quantify tissue motion and deformation. By tracking the movement of these speckles frame by frame, software derives displacement fields and computes strain and strain rate, providing a measure of how tissue deforms during the cardiac cycle or under other dynamic conditions. The method can be applied in two dimensions and, with newer systems, in three dimensions.

In practice, speckle-tracking begins with standard ultrasound frame sequences, often of the heart. A region of interest is defined, and the software follows the pattern of speckle patterns within that region across frames using correlation-based or feature-tracking algorithms. From the resulting displacement data, directional strains are calculated, typically including longitudinal, circumferential, and radial components, with global and regional summaries. Time curves of strain and strain rate can be produced for functional assessment. 2D speckle-tracking is the most widely used, while 3D methods offer more complete spatial information at the cost of higher data requirements.

Applications of speckle-tracking are most prominent in cardiology, where it is used to evaluate myocardial deformation, detect subclinical dysfunction, and characterize regional function beyond conventional measures like ejection fraction. It also has research and clinical use in other tissues, such as liver or skeletal muscle, and in vascular studies, where tissue mechanics are of interest.

Advantages include relative angle independence compared with Doppler-based measures and the ability to extract regional and global deformation from standard B-mode images. Limitations involve dependence on image quality and frame rate, vendor-specific algorithms with limited cross-vendor comparability, and susceptibility to out-of-plane motion in 2D tracking. Reproducibility and interpretation can vary with technology and experience.