Abstract
BackgroundUltrasound shear-wave elastography (SWE) may increase specificity of breast lesion assessment with ultrasound, but elasticity measurements may change with transducer orientation, defined as anisotropy. In this study, we aimed to observe the anisotropy of SWE of breast lesions, and its correlation with clinical and histopathological findings.MethodsThis retrospective study was approved by institutional review board. From June 2014 to June 2015, a total of 276 women (mean age, 48.75 ± 12.12 years) with 276 breast lesions (174 malignant, 102 benign) were enrolled for conventional ultrasound and SWE before surgical excision. Elasticity modulus in the longest diameter and orthogonal diameter were recorded, including maximum elasticity (Emax), mean elasticity (Emean), standard deviation (Esd) and ratio between mean elasticity of lesion and normal fatty tissue (Eratio). Anisotropy coefficients including anisotropic difference (AD) and anisotropy factors (AF) were calculated, and correlations with malignancy, tumor size, palpability, movability, lesion location and histopathology were analyzed.ResultsThe average Emax, Emean, Esd and Eratio of the longest diameter were significantly higher than orthogonal diameter (P < 0.05). AUCs of ADs and AFs were inferior to quantitative parameters (P < 0.001), with AUCs of AFs superior to ADs (P < 0.001). ADs showed no significant correlation with malignancy, palpability, movability, distance from nipple and skin, and histopathological patterns. ADmean was significantly higher in inner half than outer half of the breast (P = 0.034). Higher AFs were significantly correlated with larger lesion size (P = 0.042), palpability (P < 0.05), shorter distance from nipple and skin (P < 0.05) and higher suspicion for malignancy (P < 0.001). AFs were significantly higher in IDC than DCIS (P < 0.05), higher in Grade II/III than Grade I IDC (P < 0.001), and correlated with ER/PR(+) (P < 0.05).ConclusionsAF of SWE was an indicator for malignancy and more aggressive breast cancer.
Highlights
Ultrasound shear-wave elastography (SWE) may increase specificity of breast lesion assessment with ultrasound, but elasticity measurements may change with transducer orientation, defined as anisotropy
Except for 32 (11.6%) lesions detected by Quantitative elasticity of two orthogonal planes Both by considering the total lesions together and the benign group alone, the average Maximal elasticity (Emax), Mean elasticity (Emean), Standard deviation of elasticity (Esd) and Eratio were significantly higher in View A than View B (P < 0.05)
Emax and Emean were significantly higher in View A than View B (P < 0.05), without significant difference for Esd and Eratio Figs. 1, 2
Summary
Ultrasound shear-wave elastography (SWE) may increase specificity of breast lesion assessment with ultrasound, but elasticity measurements may change with transducer orientation, defined as anisotropy. In other studies, two orthogonal planes were obtained routinely, either radial/antiradial planes or transverse/longitudinal planes [10, 12], and diagnostic performance was improved by combining conventional ultrasound with two-view SWE (two orthogonal planes) compared with combining with single-view SWE (single transducer orientation) [12]. In terms of ultrasound elastograpy, anisotropy could be defined as different imaging features with the change of orientation of the transducer, resulting in different measurements of elasticity when assessing along different axes. Zhou et al has demonstrated the anisotropy of elasticity of normal breast glandular and fatty tissue by comparing measurements of radial and antiradial planes [13]. Anisotropy of other quantitative parameters such as Emax, Esd and Eratio has not been analyzed yet [15]
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