['There is no simple, cost effective bedside method available for measuring global cerebral blood flow (CBF) rapidly and repeatedly.', 'Based on the ultrasound technique a device was developed to measure flow volume per unit of time in the internal carotid artery. The system utilizes dual beam, angle-independent Doppler technology, and employs simultaneous sampling and full spectrum determination. The aim of this study was to evaluate this device in comparison with cerebral blood flow measurements using the well established Xenon(133) clearance technique.', '10 patients suffering from SAH were included. 20 measurements were performed. CBF was measured employing the Xenon(133) clearance technique. Velocity profiles across the ICA were obtained with the high-resolution FlowGuard Doppler ultrasound flow system (Cardiosonix Ltd., Israel). According to the statistical analysis the ICA flow correlated significantly to the mean rCBF15 index of the hemisphere (p<0.0001).'] Does internal carotid artery volume flow correlate to rCBF measurements?