A Rod-Like Acoustic Radiation Force in Ultrasound-Based Elastography: A Simulation Study

Many groups have dedicated to develop elasticity-imaging methods that induce tissue displacements by an acoustic radiation force (ARF). In this paper, we employ a latest model, 2-D CMUT array transducer, to generate a rod-like radiation force. Compared to spot-like force excitation, the rod-like focal force excitation has the following advantages in future practice: First, it can extend the displacement field; further, a rod-like excitation induces a shear wave field in a preferential propagation direction, which will help to measure the elastic properties in the anisotropic tissues, such as biceps and cardiac muscles. The 2-D array transducer is lateral focused at several depths with no elevational focalization by setting the delay time between the elements. The shape of rod-like focus has a length of about 16mm along the elevational direction. The uniformity and the width of the rod-like focal region at each focal depth is explored in our simulation study. Simulated results show that both the nonuniformity and the width of the focal region will increase with the focal depth. The standard deviation (SD) of the normalized pressure in the focal region will also increase with the focal depth. When the focal depth is relative near (<25mm), both the uniformity and the width of the focal region reach a satisfactory level (SD < 0.12, width< 3.2mm).