Transcranial functional shear wave elastography

Abstract

Many functional imaging modalities such as EEG, fMRI, and fUS were developed, and have the potential to achieve the brain-computer interface. In addition to those conventional functional imaging modalities which measure the electrical signal or neurovascular coupling induced by brain activity, Patz et al. found evidence for the existence of a neuromechanical coupling that can be detected by elastography. This project proposes transcranial functional shear wave elastography (SWE) that images the elasticity of the human brain tissue with ultrasound noninvasively. To correct aberration induced by the skull, we introduce an aberration correction algorithm based on ray tracing which corrects the aberration for both shear wave generation and image readout. The result shows that the aberration correction can improve the SNR and contrast of shear wave images and help the reconstruction of elasticity of agar phantom which includes an aberrator and help SWE recover the elasticity of brain tissue through the aberrator such as skull. Although transcranial functional SWE still has weakness in spatial range of measurements, temporal resolution, and spatial resolution, it has the potential to be applied to BCI as the development of shear wave tracking technique and high frame rate ultrasound imaging.