Development of a method to image blood flow beneath the skull or tissue using ultrasonic speckle reflections

The interest of our study is the in-vivo transcranial visualization of blood flow without removal of the skull. The strong attenuation, scattering, and distortion by the skull bones (or other tissues) make it difficult to use currently existing methods. However, blood flow can still be detected by using the ultrasonic speckle reflections from the blood cells and platelets (or contrast agents) moving with the blood. The methodology specifically targets these random temporal changes, imaging the flowing region and eliminating static components. This process analyzed over multiple exposures allows an image of the blood flow to be obtained, even with negative acoustic effects of the skull in play. Experimental results show this methodology is able to produce both 2D and 3D images of the flowing region, and eliminates those regions of static acoustic sources as predicted. Images produced of the flowing region are found to agree with the physical size of the vessel analogues, and also found to provide a qualitative measure on the amount of flow through the vessels.