Intraoperative brain ultrasound: a new approach to study flow dynamics in intracranial aneurysms

The aim was to evaluate the potential of contrast-enhanced ultrasound to visualize the hemodynamics in intracranial aneurysms during neurosurgical intervention and to quantify the ultrasound data using digital particle image velocimetry (DPIV) technique. Aneurysms were scanned through the intact dura mater, preclipping and again postclipping after closure of the dura. After intravenous injection of Optison, angio-like views of the vascular tree surrounding the aneurysm, including the aneurysm sac, were obtained. Single ultrasound contrast agent microbubbles could be visualized in the aneurysm sac and the flow dynamics could be assessed in vivo. Spatial and temporal distributions of the velocity in the aneurysm and in the parent vessels were measured with DPIV using the backscattered signals from the microbubbles. Subsequently, the fluid stresses, vorticity, circulation, etc., were calculated from the velocity fields. We demonstrate in this paper that intraoperative contrast-enhanced ultrasound can be used to quantify the flow dynamics within an aneurysm.