A novel transcranial ultrasound imaging method with diverging wave.

Real time transcranial ultrasound imaging of brain can be extremely intriguing because of its numerous applications. In this study, we proposed an ultrafast transcranial ultrasound imaging technique with diverging wave (DW) transmission, which has been a promising technique to image moving objects, such as complex blood flow field and transient elastography. However, diverging waves are all unfocused waves, which makes their image quality, especially the lateral resolution and contrast, has not yet been satisfactory. Here we tried to apply the adaptive beamforming algorithms to improve both the image contrast and the lateral resolution. Simulation and phantom experiments proved that our methods can significantly improve the DW image quality. Finally, transcranial ultrasound imaging collected through temporal bone were presented and analyzed. The ultrasound frequency used in this study ranges from 2 MHz to 4 MHz, centered at 2.8 MHz. Since the wavefront was offset and distorted after passing through temporal bone, the image quality will be slightly degraded. Even then, it was demonstrated that these adaptive algorithms can significantly improve the transcranial image quality, especially the image contrast.