Comparison of peritumoral stroma tissue stiffness obtained by shear wave elastography between benign and malignant breast lesions

Background: Aggressive breast cancers produce abnormal peritumoral stiff areas, which can differ between benign and malignant lesions and between different subtypes of breast cancer. Purpose: To compare the tissue stiffness of the inner tumor, tumor border, and peritumoral stroma (PS) between benign and malignant breast masses by shear wave elastography (SWE). Material and Methods: We enrolled 133 consecutive patients who underwent preoperative SWE. Using OsiriX commercial software, we generated multiple 2-mm regions of interest (ROIs) in a linear arrangement on the inner tumor, tumor border, and PS. We obtained the mean elasticity value (E-mean) of each ROI, and compared the E mean between benign and malignant tumors. Odds ratios (ORs) for prediction of malignancy were calculated. Subgroup analyses were performed among tumor subtypes. Results: There were 85 malignant and 48 benign masses. The E-mean of the tumor border and PS were significantly different between benign and malignant masses (P < 0.05 for all). ORs for malignancy were 1.06, 1.08, 1.05, and 1.04 for stiffness of the tumor border, proximal PS, middle PS, and distal PS, respectively (P < 0.05 for all). Malignant masses with a stiff rim were significantly larger than malignant masses without a stiff rim, and were more commonly associated with the luminal B and triple negative subtypes. Conclusion: Stiffness of the tumor border and PS obtained by SWE were significantly different between benign and malignant masses. Malignant masses with a stiff rim were larger in size and associated with more aggressive pathologic subtypes.