Shearwave Elasticity Measurements of Breast Fat

Background: The fatty tissue of the breast is commonly used as a reference for assessing relative strain, but its normal variation has not been documented. The aim of this study was to measure the elasticity of breast fat in kilo Pascals using shearwave elastography (SWE) in women of different ages. SWE was performed on 1000 women in the multicenter BE1 study of breast masses; measurements of the subcutaneous fat adjacent to the lesion in kPa were made using SWE on a prototype of the Aixplorer system (Supersonic Imagine, Aix-en-Provence, France). The values were compared with the patients age and with the type of pathology (benign or malignant). The mean age of the patients was 52.1 years (SD + /-;14.8, range 21.2 to; 95.3). The mean elasticity value was 14.1 kPa (SD +/-10.92, range 0.03 to 130.8). The mean values ranked against the patients age by decade were: 20-30: 11.6; 30-40: 12.1; 40-50: 14; 60-70: 15.5; 70-80: 14.2; over 80: 17 kPa. The slight trend to a higher value with age was significant (p 0.001). Fat in the patients with benign masses had a mean elasticity of 13.1 kPa while in the malignant group the mean value was 15.9kPa. This is the first quantitative assessment of the stiffness of breast fatty tissue. The elasticity varied little with age or pathology, supporting the use of fat stiffness as a comparator. The BE1 study was supported by SuperSonic Imagine, Aix-en-Provence, France.