Diagnostic accuracy of shear wave elastography for prediction of breast malignancy in patients with pathological nipple discharge

Abstract

Objectives: Pathological nipple discharge (PND) may indicate malignant breast lesions. As the role of shear wave elastography (SWE) in predicting these malignant lesions has not yet been evaluated, we aim to evaluate the diagnostic value of SWE for this condition.

Design: Prospective diagnostic accuracy study comparing a combination of qualitative and quantitative measurements of SWE (index test) to a ductoscopy and microdochectomy for histological diagnosis (reference test).

Setting: Fuzhou General Hospital of Nanjing military command.

Participants: A total of 379 patients with PND were finally included from January, 2011 to March 2014, after we screened 1084 possible candidates. All participants were evaluated through SWE, with qualitative parameters generated by Virtual Touch tissue imaging (VTI) and quantitative parameters generated by Virtual Touch tissue quantification (VTQ). All the patients were consented to receive a ductoscopy and microdochectomy for histological diagnosis, and the results were set as a reference test.

Outcome measures: Sensitivity and specificity of the combined VTI and VTQ of the SWE for detection of malignancy in patients with PND.

Results: The 379 participants presented with 404 lesions. The results of pathological examination showed that 326 (80.7%) of the 404 lesions were benign and the other 78 (19.3%) were malignant. An area under the curve of elasticity score, VTQm and VTQc, were 0.872, 0.825 and 0.857, respectively, with the corresponding cut-off point as 2.50, 2.860 m/s and 3.015 m/s, respectively. After a combination of these measurements, the sensitivity, specificity, and positive and negative predictive value (PPV and NPV), were 89.7%, 72.1%, 43.5% and 96.7%, respectively. The sensitivity analysis showed 82% of the sensitivity and 96.8% of the specificity, in which patients with no pathological findings in ductoscopy were excluded.

Conclusions: Ultrasonographic elastography is sensitive for patients with PND and could be used as a triage test before ductoscopy examination. Studies for further improvement of diagnostic sensitivity are warranted.

Keywords: ONCOLOGY.

Figure 1

Flow chart of this study. * There were 379 participants presenting 404 lesions. In the results, we counted the number of lesions instead of the patients. The index test is shear wave elastography on the basis of B-mode ultrasound. The reference test is ductoscopy and subsequent microdochectomy if pathological changes were found in ductoscopy.

Figure 2

The image of a 45-year-old patient with invasive ductal carcinoma. The left picture showing a B-mode ultrasonography locating the region of interest (ROI). The right picture showing the elastography of the breast lesion, with a blue colour indicating a harder tissue and a red colour indicated a softer tissue.

Figure 3

The image of a 41-year-old patient with fibroadenoma. B-mode ultrasonography at the left showing the location of the region of interest (ROI). An elastography picture on the right shows the elasticity of the fibroadenoma.

Figure 4

The receiver-operating-characteristics (ROC) curve of elasticity score, VTQm and VTQc. VTQm, virtual touch quantification at margin of a lesion. VTQc, virtual touch quantification at the centre of a lesion. The figure shows the area under the curve (AUC), specificity and sensitivity of Elasticity score, VTQm and VTQc. A cut-off point of 2.50 was selected for elasticity score yielding a sensitivity of 0.872 (95% CI 0.795 to 0.940), a specificity of 0.736 (95% CI 0.660 to 0.805) and an AUC of 0.854. A cut-off point of 2.860 m/s was selected for VTQm yielding a sensitivity of 0.731 (95% CI 0.628 to 0.821), a specificity of 0.742 (95% CI 0.673 to 0.805) and an AUC of 0.825. Additionally, a cut-off point of 3.015 m/s was calculated for VTQc with a sensitivity of 0.731 (95% CI 0.628 to 0.821), a specificity of 0.698 (95% CI 0.616 to 0.761) and an AUC of 0.857.