Dependency of ultrasonic Nakagami images on the mechanical properties of scattering medium

Nakagami images based on backscattered statistics have been demonstrated to complement the ultrasonic B-scan technique for evaluating the arrangements and concentrations of scatterers in the scattering medium. This study explores the relationship between Nakagami images and the mechanical properties of the scattering medium. Experiments were performed on phantoms with various stiffnesses and scatterer concentrations. A commercial supersonic shear imaging system was used to measure the shear modulus of each phantom. The ultrasonic backscattered signals from the phantoms were acquired using a single-element ultrasound scanner for Nakagami imaging. The Nakagami images were compared with the supersonic shear images to explore the dependency of the Nakagami parameter on the medium stiffness. The brightness of the shading in the Nakagami image increased with increasing stiffness of the phantom. For the scattering medium with a low scatterer concentration (8 scatterers.mm^-3), the average Nakagami parameter increased from 0.35 to 0.46 when the average shear modulus increased from 11.7 to 167.6 kPa. The average Nakagami parameter measured in the medium with a high scatterer concentration (32 scatterers.mm^-3) increased from 0.8 to 0.89 when the shear modulus increased from 12.3 to 174.5 kPa. This study demonstrates that the features of Nakagami images depend on the stiffness of the scattering medium.