# Speckle-Tracking Echocardiography in Dogs: Evaluating Imaging Parameters and Methodological Variability in Global Longitudinal Strain Assessment

## TL;DR

This study examines how technical factors affect the accuracy of heart function measurements in dogs using 2D-STE and compares two analysis methods.

## Contribution

The study identifies key factors influencing GLS measurements and evaluates the reliability of two 2D-STE methods in dogs.

## Key findings

- Foreshortening and heart rate variability significantly affect GLS measurements in dogs.
- 2D strain and AFI methods show good correlation but cannot be used interchangeably due to systematic bias.
- Observer variability is low, with coefficients of variation below 9% for both methods.

## Abstract

Two-dimensional speckle-tracking echocardiography (2D-STE) is a valuable tool for assessing myocardial function by measuring myocardial deformation. This prospective cohort study investigates 2D-STE. The first part of this study evaluated the influence of heart rate, frame rate, foreshortening, zoom, and transducer frequency upon global longitudinal strain (GLS) in 16 healthy dogs. The second part of the study compared GLS values obtained with GE Healthcare’s two 2D-STE methods: quantitative analysis of the 2D strain (2D strain) and automated function imaging (AFI) in 10 dogs. Our findings demonstrate that foreshortening of the left ventricle (p < 0.01, Cohen’s d: 0.52, CI: −17.81 to −24.83) and heart rate variation (p = 0.02, Cohen’s d: 0.72, CI: −18.07 to −26.23) significantly affect the GLSA4C in dogs, which should be considered in clinical and research applications. There was a good correlation between the 2D strain and AFI-obtained 2D-STE parameters, as well as low interobserver variability (between an experienced and a novice observer). However, due to systemic bias, the 2D strain and AFI should not be used interchangeably.

Two-dimensional speckle-tracking echocardiography (2D-STE) is an advanced imaging technique that offers quantitative insights into myocardial function by analyzing the motion of speckles created during ultrasound–tissue interactions. This study aims to evaluate the reliability of 2D-STE by examining the impact of key technical parameters on global longitudinal strain (GLS) measurement accuracy and comparing two speckle-tracking analysis methods provided by GE Healthcare: quantitative analysis of the 2D strain (2D strain) and automated function imaging (AFI). The prospective study consisted of two cohorts. In the first cohort, including 16 healthy dogs, the influence of frame rate, heart rate variation, zoom, transducer frequency, and image foreshortening on speckle-tracking values was assessed. In the second cohort, which included 10 healthy dogs, 2D-STE parameters were obtained with the 2D strain and AFI to assess agreement between the methods and observer variability. Our findings indicate that foreshortening (p < 0.01, Cohen’s d: 0.52, CI: −17.81 to −24.83) and heart rate variability (p = 0.02, Cohen’s d: 0.72, CI: −18.07 to −26.23) significantly affect speckle-tracking measurements. While zoom, frame rate, and frequency did not show a significant impact. Additionally, while the 2D strain and AFI exhibited a strong correlation, a significant systematic bias was identified, with AFI underestimating strain values compared to the 2D strain. Intra- and inter-observer coefficients of variation (CV) were below 9% for both methods, supporting their reliability. These findings emphasize the need to optimize image acquisition and selection criteria, which enhances the accuracy and reliability of the speckle-tracking analysis.