Shear-wave elastography of partly cystic breast lesions, does it always help

Purpose: To investigate range of pathological findings in partly cystic in ultrasound and to evaluate role of SWE in differential diagnosis Methods and Materials: Out of 567 cases,72 breast lesions with partly cystic appearance in B-mode, SWE images were also obtained and correlated with pathological results which was available in 65 patients. Qualitative and quantitative tissue elasticity were displayed with color-coded map and color scale ranging from 0kPa (dark blue; soft) to180kPa (red; stiff).Quantitative elasticity values were measured by drawing a Q box over the stiffest portion and another box on adjacent normal breast tissue. Maximum color and presence of a stiff rim was recorded. Maximum and mean stiffness, also ratio of lesion stiffness to surrounding tissue were compared using Mann Whitney U test. Results: lesions with cystic components including 29complicated cysts, 29complex solid cystic masses, 3intracystic masses, and 11clusters of micro cysts. Pathologic results included 5 invasive carcinomas (two IDC with medullary features, one medullary carcinoma, one papillary carcinoma) 57nonhigh risk and4high-risk (fibrocystic changes with atypical ductal hyperplasia, or atypical ductal papillomatosis and papillary lesion) benign pathologies. All clusters of micro cysts were low-risk benign lesions except one case with high risk pathology, atypical ductal papillomatosis. Mean and maximum stiffness and stiffness ratio were not significantly different between the benign and malignant groups. (P=0.606, 0.391 and, 0.213 respectively) Conclusion: In complex solid cystic masses, SWE is less helpful in differentiating benign and malignant masses. This can be explained by the fact that many partly cystic cancers are medullary, mucinous or papillary which are usually softer in consistency. Other mass features need to be considered before downgrading a partly cystic mass based on stiffness values.