Transcranial Doppler Ultrasound: Technique and Application

Abstract

Transcranial Doppler (TCD) ultrasound provides rapid, noninvasive, real-time measures of cerebrovascular function. TCD can be used to measure flow velocity in the basal arteries of the brain to assess relative changes in flow, diagnose focal vascular stenosis, or to detect embolic signals within these arteries. TCD can also be used to assess the physiologic health of a particular vascular territory by measuring blood flow responses to changes in blood pressure (cerebral autoregulation), changes in end-tidal CO2 (cerebral vasoreactivity), or cognitive and motor activation (neurovascular coupling or functional hyperemia). TCD has established utility in the clinical diagnosis of a number of cerebrovascular disorders such as acute ischemic stroke, vasospasm, subarachnoid hemorrhage, sickle cell disease, as well as other conditions such as brain death. Clinical indication and research applications for this mode of imaging continue to expand. In this review, the authors summarize the basic principles and clinical utility of TCD and provide an overview of a few TCD research applications.

Neurovascular coupling in humans: Physiology, methodological advances and clinical implications

“…52,55,73,92,93 Lastly, often only the posterior window is suitable for insonating intracranial vessels in the elderly, due to skull thickening with advancing age. 94 Some studies have reported that 10À15% of individuals will have inadequate windows for insonating intracranial cerebral vessels; 95 as such, it may be advantageous to utilize other techniques such as NIRS (see next section) in addition to TCD for studies in the elderly or those with related cerebrovascular pathology.…”

Apixaban Inhibits Cerebral Microembolic Signals Derived from Carotid Arterial Thrombosis in Rabbits

“…Microembolic signals (MESs) in patients with carotid stenosis, myocardial infarction, atrial fibrillation, and mechanical cardiac valves are often detectable in the cerebral circulation by a transcranial Doppler (TCD; Levi et al, 1997;Purkayastha and Sorond, 2012). Clinical evidence has demonstrated that the presence of MES in the cerebral circulation is an independent predictor of the risk and prognosis of stroke (Gao et al, 2004;Markus et al, 2005) and recurrence in patients with previous stroke or transient ischemic attack (TIA) of presumed arterial origin (Valton et al, 1998).…”

Detecting peripersonal space: The promising role of ultrasonics

“…We chose Transcranial Doppler ultrasound (TCD) to monitor CBF changes because of its low cost, excellent temporal resolution and sensitivity to CBF changes within the circle of Willis and the large intracranial vessels, as shown in a variety of neurologic disorders (Purkayastha & Sorond, 2012). The variables we measured are commonly used to estimate cerebrovascular responsiveness to various stimuli (Watt, Burnfield, Truemper, Buster, & Bashford, 2012).…”

“…The variables we measured are commonly used to estimate cerebrovascular responsiveness to various stimuli (Watt, Burnfield, Truemper, Buster, & Bashford, 2012). In particular, one can estimate the distal cerebrovascular resistance by measuring the PI, which depends on multiple hemodynamic variables including the metabolic changes during cognitive tasks (thus being possible to indirectly estimate changes in brain metabolism) (D'Andrea et al., 2016; Demarin & Morovic, 2014; Kenney et al., 2016; Kim & Lee, 2015; Purkayastha & Sorond, 2012; Wolf, 2015). …”