Can measuring perilesional tissue stiffness and stiff rim sign improve the diagnostic performance between benign and malignant breast lesions?

To evaluate tissue stiffness values around breast lesions and stiff rim sign for the differentiation of benign and malignant lesions. A total of 192 patients (mean age, 44.6 ± 13.6 years) with 199 breast lesions were included in this retrospective study. All lesions were pathologically proven by US-guided core needle biopsy (CNB), Mammotome biopsy, or surgery. We first observed the presence or absence of a stiff rim sign, which was defined as a red or orange halo around the breast lesion. The shell around the breast lesion on SWE was then automatically drawn by machine, with a width of 1 mm, 2 mm, and 3 mm. The elasticity moduli of the lesion and surrounding tissue were recorded, including maximum elasticity (Emax), mean elasticity (Emean), minimum elasticity (Emin), and elasticity ratio (shell/lesion ratio). The optimal thresholds of elasticity moduli were calculated according to the receiver operating characteristic (ROC) curve. There were 75 malignant lesions and 124 benign ones. The average Emax and Emean of lesions and shell were significantly higher in the malignant group than in the benign group (P < 0.05). The optimal cut-off value of Emax for diagnosing malignant lesions was 101.7 kPa, with a sensitivity of 66.3% and specificity of 87.9%. The optimal cut-off value of Emean was 29.1 kPa, with a sensitivity of 65.3% and specificity of 79.8%. The stiff rim sign had the highest diagnostic performance for malignancy as compared with other elastic parameters, with an accuracy of 88.4%. However, measuring peritumoral tissue stiffness can achieve relatively high sensitivity, whereas specificity was not improved significantly. The stiffness of tissue surrounding breast malignancies was significantly higher than the surrounding benign lesions. Stiff rim sign has the potential to improve the diagnostic performance of breast lesions.