ANISOTROPIC PROPERTIES OF BREAST TISSUE MEASURED BYACOUSTIC RADIATION FORCE IMPULSE QUANTIFICATION

The goal of our study was to investigate the anisotropy of normal breast glandular and fatty tissue with acoustic radiation force impulse (ARFI) quantification. A total of 137 breasts in 137 women were enrolled. These breasts were divided into the duct-apparent group and the duct-inapparent group, divided into the ligament-apparent group and the ligament-inapparent group. Shear wave velocity (SWV) in the radial (SWVr) and anti-radial (SWVa-r) directions was measured. The elastic anisotropy of glandular tissue and fatty tissue was evaluated as the ratio between SWVr and SWVa-r. The SWV ratio was 1.30 +/- 0.45 for glandular tissue and 1.27 +/- 0.53 for fatty tissue in the total group. In glandular tissue, the SWV ratio of the duct-apparent group was higher than that of the duct-inapparent group (p = 0.011). In both glandular and fatty tissue, the SWV ratio was higher in the ligament-apparent group than in the ligament-inapparent group (p < 0.05 for both). SWVr was higher than SWVa-r in both glandular tissue and fatty tissue in all groups ( p, 0.05 for all) except in breast fatty tissue in the ligament-inapparent group (p = 0.913). It is concluded that both breast glandular tissue and fatty tissue exhibited anisotropy of elastic behavior. To improve the diagnostic power of elastography in breast lesions, the elastic anisotropy of glandular tissue and fatty tissue should be taken into account in calculating strain ratio or elasticity ratio. (C) 2016 World Federation for Ultrasound in Medicine & Biology.