A Comparative Study of Strain and Shear-Wave Elastography in an Elasticity Phantom

Abstract

OBJECTIVE. The purpose of this study was to assess the diagnostic accuracy of strain and shear-wave elastography for determining targets of varying stiffness in a phantom. The effect of target diameter on elastographic assessments and the effect of depth on shear-wave velocity were also investigated. MATERIALS AND METHODS. We examined 20 targets of varying diameters (2.5-16.7 mm) and stiffnesses (8, 14, 45, and 80 kPa) with a 4-9-MHz linear-array transducer. Targets were evaluated 10 times with three different methods-shear-wave elastography, strain ratio, and strain histogram analysis-yielding 600 evaluations. AUCs were calculated for data divided between different stiffnesses. A 1.5-6-MHz curved-array transducer was used to assess the effect of depth (3.5 vs 6 cm) on shear-wave elastography in 80 scans. Mixed model analysis was performed to assess the effect of target diameter and depth. RESULTS. Strain ratio and strain histogram AUCs were higher than the shear-wave velocity AUC (p < 0.001) in data divided as 80 versus 45, 14, and 8 kPa. In data divided as 80 and 45 versus 14 and 8 kPa, the methods were equal (p = 0.959 and p = 1.000, respectively). Strain ratios were superior (p = 0.030), whereas strain histograms were not significantly better (p = 0.083) than shear-wave elastography in data divided as 80, 45, and 14 versus 8 kPa. Target diameter had an effect on all three methods (p = 0.001). Depth had an effect on shear-wave velocity (p = 0.001). CONCLUSION. The ability to discern different target stiffnesses varies between shear-wave and strain elastography. Target diameter affected all methods. Shear-wave elastography is affected by target depth.

Elastography and diffusion-weighted MRI in patients with rectal cancer

“…The rectal tumours in the present study had a mean diameter of 4.1 cm, which is considerably larger than the lesions in the phantom study by Carlsen et al, 19 and we could not find a relation between size and stiffness in rectal cancer.…”

“…Another limitation is that shear wave elastography is affected by target depth. 19 We did not use the short, direct contact elastography by ERUS, but the external transgluteal window, which gives a longer distance between the transducer and the target. Also, we did not perform an interobserver and intraobserver study of the patients.…”

“…According to a new phantom study by Carlsen et al, 19 the lesion diameter has a significant effect on shear wave elastography, and ARFI displays limitation as to discrimination of stiffness in very small lesions. The rectal tumours in the present study had a mean diameter of 4.1 cm, which is considerably larger than the lesions in the phantom study by Carlsen et al, 19 and we could not find a relation between size and stiffness in rectal cancer.…”

Clinical acceptance testing and scanner comparison of ultrasound shear wave elastography

“…These tasks could be faced by many clinical imaging physicists nowadays. Systemic differences were shown among different transducers and vendors, which were similarly observed in the literature 18, 21, 22…”

Strain sonoelastography of inflammatory myopathies: comparison with clinical examination, magnetic resonance imaging and pathologic findings

“…13,14 Quantitative shear-wave imaging technique has problem with the linear probe because it is affected by target depth. 15 Shear wave does not allow sufficient elastogram in proximal thigh muscles, which are the most commonly involved site of IM. 12,[16][17][18][19] Although IM have been previously studied using conventional ultrasonography and MRI, there are only a few studies in the literature that have attempted to use SSE in IM.…”