A Preliminary Analysis on 3D Shear Wave Elastography With Laboratory X-Ray Source

Elastography is a technique to assess the elastic properties of tissues and is currently used for diagnostics. In shear wave elastography, the elastic properties of tissue are estimated by finding propagation velocities of shear waves induced by external stimuli. Ultrasound imaging, magnetic resonance imaging, and X-ray imaging can be used to measure tissue displacements caused by shear waves. X-ray imaging may enable assessment of elastic properties at deep locations with high spatial resolution due to its short wavelength. We demonstrated three-dimensional X-ray elastography on an agarose gel sample. Firstly, we took projection images of the sample at a vibration frequency of 100 Hz with a detector frame rate of 10,000 fps while rotating the sample at π rad/s. Next, three-dimensional images were reconstructed from projection images which were taken at the same phases of the vibration. Totally 100 three-dimensional images were reconstructed. The displacements were then calculated by a non-rigid registration method. Finally, we obtained storage and loss moduli by using an algebraic inversion of the differential equation method, which derives the elastic moduli from differential wave equations.