Use of Transcranial Doppler in the Outpatient Ultrasound Lab

Abstract

The objective of this chapter is to elucidate the many ways a dedicated outpatient neurovascular ultrasound lab (NVUL) with carotid duplex and transcranial Doppler (TCD) services benefits patient care for both primary and recurrent stroke prevention and treatment. This chapter also highlights the unique clinical and investigative tools for translational and basic research in neurovascular physiology and neuroscience generally that the NVUL offers. While many peripheral vascular labs can provide “cerebrovascular exams,” this usually means only carotid duplex exams are being offered. In the United States, TCD services are typically available only in specially staffed and dedicated neurovascular ultrasound labs attached to comprehensive stroke centers. Alongside these in-hospital labs, however, it is the outpatient neurovascular lab that has an additional role to play in secondary stroke prevention. For the outpatient returning for follow-up after their transient ischemic attack (TIA) or stroke, the dedicated outpatient NVUL provides an integrated cerebrovascular and neurovascular ischemic assessment by having carotid duplex exams performed at the same time and in the same place as the outpatient’s TCD exam. TCD is a noninvasive imaging modality that can often replace or surpass the utility of functional MRI for some basic and clinical research purposes at cheaper cost. For many research purposes needing the embolic and continuous monitoring tools of TCD, the outpatient facility is ideally situated when considering logistical and resource requirements for patient access and operational costs (especially in academic medical centers affiliated with hospitals). A case study illustrating the combined use of carotid duplex and TCD. Discussion of current trends in cryptogenic stroke and ESUS research and interventions by referencing the MOST-Cancer trial concluded in 2020. Discussion of other current research trends in neuroscience where TCD has been applied and demonstrates unique utility.