RF signals provide additional information on embolic events recorded during TCD monitoring

Transcranial Doppler ultrasound (TCD) is commonly used to detect embolic signals in the cerebral circulation. However, current techniques to discriminate between signals from emboli and artifacts are subjective and ambiguous. The radiofrequency (RF) signal provides an extra dimension to the information available from conventional TCD systems that may help to interpret complex events. Artifacts generated by healthy volunteers and embolic signals recorded from a flow phantom were used to characterize the appearance of the two types of event. Characteristics of events, recorded during and immediately after carotid endarterectomy surgery, were compared with those from known sources. Additional information was provided by the RF signal on events recorded during TCD monitoring thus aiding classification. The RF signal may have a role as a "gold standard" for embolus detection.