Real time 3D ultrasound imaging of the brain

We tested the feasibility of real time 3D ultrasound imaging in the brain with a 2.5 MHz 2D array using a Volumetrics Model 1 scanner. In a human subject, the scans produced simultaneous transcranial axial, coronal and saggital image planes and real time volume rendered images of the gross anatomy of the brain. In a transcranial sheep model we obtained real time 3D color flow Doppler scans of cerebral vessels as well as perfusion images using bolus injection of contrast agents into the internal carotid artery. Our long term goal includes phase aberration correction of the skull using the 2D array. Phase aberration measurements have been made from both polymer castings of the temporal bone region and of a fixed human parietal bone. Severe aberration data from the skull bone indicates a significant potential improvement in image quality yet to be realized in real time transcranial sonography. Using the multi-lag least-squares cross-correlation method, we have corrected an electronically aberrated 3D scan, leading to an increase in contrast-to speckle ratio (CSR) and contrast in a cyst phantom.