In vitro evaluation of ultrasound Doppler strain rate imaging: modification for measurement in a slowly moving tissue phantom

Abstract

Doppler strain rate imaging (SRI) was evaluated in vitro using a silicone strip phantom mimicking slowly moving tissue. A test apparatus was developed that enabled controlled strain experiments with variable strain and strain rate to be performed. SRI strain was measured at eight different calculated strains (range 5.7 to 63.4 %) at three different pump speeds with tissue velocity 0.1, 0.5 and 1.0 mm/s. The effect of varying tissue velocity and strain sample size on the measured SRI strain was elaborated. SRI strains agreed well with calculated values for strain when SRI strain was measured as the average over the whole strip cross-section and the strain sample size was 1.9 mm (mean difference = 2.78%, limits of agreement +/- 9.97% for tissue velocity 1.0 mm/s, n = 8). The variance was substantial if single central samples were used, especially for strain sample size of 0.8 mm (mean difference = -7.47%, limits of agreement +/- 20.90 for tissue velocity 0.5 mm/s, n = 24). Increasing the strain sample size to 1.9 mm removed some of the underestimation (giving mean difference of -4.46%, n = 24). We found low intra- and interobserver variation. This study indicates that, for the SRI method to give accurate estimates of strain, strain sample size should be in the region of 2 mm. Averaging over several ultrasound (US) beams increased the accuracy further.

Evaluation of ultrasound Tissue Velocity Imaging: a phantom study of velocity estimation in skeletal muscle low-level contractions

“…In addition, Doppler strain rate has earlier also been evaluated in slowly moving tissue (0.01-0.1 cm/s) using a phantom mimicking the gastric wall. However in this study the PRF was kept very low through all measurements and instead the sample size and sample geometry for calculating strain rate were tested [19]. …”

Imaging of Tissue Elasticity in Gastrointestinal Disorders

“…The accuracy of SRI was evaluated in vitro using a silicone strip phantom mimicking slowly moving tissue (Matre et al 2003) and in measuring strain in the porcine antral wall in vitro (Ahmed et al 2006). SRI demonstrated accurate measurement of radial strain of the antral wall and low intra-and inter-observer variation.…”

Ultrasonography of the Stomach

“…SRI has been validated in vivo with a silicone phantom to mimic moving tissue (Matre et al, 2003) and in an in vitro porcine model (Ahmed et al, 2006). In a study involving the artificial distension of the antrum with a barostat device, there was a significant inverse correlation between balloon pressure and gastric strain .…”