2090662 Shear Wave Elastography - Four Essential Color Map Patterns To Rule Out Breast Malignancy

Abstract

Shear wave elastography (SWE) is a non-invasive imaging technique which provides quantitative tissue elasticity data on breast lesions in addition to conventional ultrasonography (US). The aims of this study are to define the simple color map patterns to rule out malignancy, and evaluate the relationship between SWE findings and biological features of the breast carcinoma in Asian population. This is a retrospective, single center study which included 103 women (age range, 21-91 years) with 104 solid breast lesions identified during routine US performed between June 2013 and May 2014. All breast lesions were subsequently confirmed either by cytological or histological examinations. Obtained SWE images were classified into four patterns: No color on elastography image (pattern 1), vague longitudinal artifact inside the lesion (pattern 2), positive findings only at the surrounding area (pattern 3), and positive findings both at the boundary and inside the lesion (pattern 4). Eligible lesions were then evaluated for the mean quantitative elasticity values in regions of interest (ROI) placed over the stiffest area and the fat area to obtain the tumor/fat SWE ratio (TFSWR). Among the 104 lesions, 44 were malignant and 60 were benign. Color map patterns 1, 2, 3, and 4 were observed in 32, 19, 18, 35 cases respectively. Both patterns 1 and 2 lesions were 100% benign, whereas patterns 3 and 4 included 72% and 89% malignancies respectively. The results for combined US and SWE yielded 100% sensitivity, 85% specificity, 83% positive predictive value, 100% negative predictive value. The mean TFSWR was 18.4±9.7 vs 3.2±5.8 (p<0.001) for malignant and benign lesions. No malignant lesion showed TFSWR of higher than 5, whereas 9 (15%) benign lesions were present within. The TFSWR and hormone receptor status, HER2 status, histological grade, invasive size, lymph node status were not statistically relevant. In addition to conventional US, SWE color map patterns of 1 and 2, and TFSWR of less than 5 excluded all the breast malignancies. SWE results were not associated with any of the biological features of breast carcinoma in Asian population.