Evaluation of internal and shell stiffness in the differential diagnosis of breast non-mass lesions by shear wave elastography

Abstract

Background: The diagnostic specificity of conventional ultrasound for breast non-mass lesions (NMLs) is low at approximately 21%-43%. Shear wave elastography (SWE) can distinguish benign from malignant lesions by evaluating the internal and peripheral stiffness. SWE has good reproducibility and high diagnostic efficacy. However, there are very few independent studies on the diagnostic value of SWE in breast NMLs.

Aim: To determine the value of SWE in the differential diagnosis of breast NMLs.

Methods: This study enrolled a total of 118 patients with breast NMLs who underwent SWE examinations in the Beijing Shijitan Hospital Affiliated to Capital Medical University and The Second Hospital of Shandong University from January 2019 to January 2020. The internal elastic parameters of the lesions were recorded, including maximum (Emax), mean (Emean) and minimum elastic values and the standard deviation. The following peripheral parameters were noted: Presence of a "stiff rim" sign; Emax, and Emean elasticity values within 1 mm, 1.5 mm, 2 mm, 2.5 mm and 3 mm from the edge of NMLs. The receiver operating characteristic curve of each parameter was drawn, and the areas under the curve were calculated.

Results: Emax, Emean and elastic values, and the standard deviation of the internal elastic values in malignant NMLs were significantly higher than those in benign NMLs (P < 0.05). The percentage with the "stiff rim" sign in malignant NMLs was significantly higher than that in the benign group (P < 0.05), and Emax and Emean at the shell of 1 mm, 1.5 mm, 2 mm, 2.5 mm and 3 mm in the malignant group were all higher than those in the benign group (P < 0.05). Of the surrounding elasticity values, Emax of the shell at 2.5 mm in malignant NMLs had maximum areas under the curve of 0.900, and the corresponding sensitivity and specificity were 94.57% and 85.86%, respectively.

Conclusion: The "stiff rim" sign and multiple quantitative elastic values within and around the lesion had good diagnostic performance in the differential diagnosis of breast NMLs. Emax in peripheral tissue had better diagnostic efficiency than other parameters.

Keywords: Breast tumor; Diagnosis; Non-mass lesions; Shear wave elastography; Stiff rim sign; Ultrasound.

Figure 1

Mass-velocity dynamic dual pattern. Homogeneous green background is shown on the left image. The “stiff rim” sign (a ring of red and orange round the lesions) is shown on the right image. RLB index: Reliable index.

Figure 2

Gray-scale-velocity dual pattern. The traced line of the outer edge (white circle) of the NMLs and the shell at 2.5 mm (pink circle) can be seen on the left image. A “stiff rim” of red and orange can also be seen on the right image. Mean, maximum, and minimum elastic values and the standard deviation were 33.80 kPa, 92.869 kPa, 6.23 kPa and 14.41 kPa, respectively, for internal elasticity, and 81.15 kPa, 167.97 kPa, 5.03 kPa and 28.05 kPa, respectively, for the shell at 2.5 mm. The pathology result was infiltrating ductal carcinoma. A: The area within the lesion. Shell: The area around the lesion. Emax: Maximum; Emean: Mean; Min: Minimum; Esd: Elastic values and the standard deviation.

Figure 3

Gray-scale-velocity dual pattern. This shows the traced line of the outer edge (white circle) of the NMLs and the shell at 2.5 mm (pink circle) on the left image, and no “stiff rim” on the right image. Mean, maximum, minimum elastic values and the standard deviation were 17.03 kPa, 40.89 kPa, 3.23 kPa and 6.93 kPa, respectively, for internal elasticity, and 12.74 kPa, 37.00 kPa, 2.51 kPa and 7.90 kPa, respectively, for the shell at 2.5 mm. The pathology result was adenosis. A: The area within the lesion; Shell: The area around the lesion. Emax: Maximum; Emean: Mean; Min: Minimum; Esd: Elastic values and the standard deviation.

Figure 4

Receiver operating characteristic curves for internal and peripheral elasticity parameters of the shell at 1 mm, 1.5 mm, 2 mm, 2.5 mm, and 3 mm, respectively. A: Receiver operating characteristic curves for internal elasticity parameters maximum (Emax), mean (Emean), minimum (Emin) elastic values and the standard deviation (Esd), the area under the curve (AUC) was 0.707, 0.626, 0.425 and 0.687, respectively; B: Emax and Emean of the shell at 1 mm (as E1max and E1mean), AUC was 0.795 and 0.647 respectively; C: Emax and Emean of the shell at 1.5 mm (as E1.5max and E1.5mean), AUC was 0.789 and 0.692, respectively; D: Emax and Emean of the shell at 2 mm (as E2max and E2mean), AUC was 0.826 and 0.704, respectively. E: Emax and Emean of the shell at 2.5 mm (as E2.5max and E2.5mean), AUC was 0.900 and 0.746, respectively; F: Emax and Emean of the shell at 3 mm (as E3max and E3mean), AUC was 0.881 and 0.734, respectively. Emax: Maximum; Emean: Mean; Min: Minimum; Esd: Elastic values and the standard deviation; AUC: The area under the curve.