Practice Standards for Transcranial Doppler Ultrasound (TCD)

An interdisciplinary panel of experts exchanged knowledge and worked in parallel on the topic “non-imaging TCD, indications, applications and outcomes” for the American Society of Neuroimaging Practice Guidelines Committee.
Their respective expertise and perspectives contributed to illuminate the TCD method comprehensively and resulted in the article: “Practice Standards for Transcranial Doppler (TCD) Ultrasound. Part II. Clinical Indications and Expected Outcomes” published in the Journal of Neuroimaging in 2012.

TCD Clinical Applications and Procedures

This panel of experts considered existing clinical conditions for which a variety of TCD tests and monitoring are performed in clinical practice: sickle cell disease, cerebral ischemia, detection of right-to-left shunts (RLS), subarachnoid hemorrhage, brain death, and periprocedural or surgical monitoring. The following TCD-procedures are performed in routine in- and outpatient clinical practice: complete or partial TCD-examination to detect normal, stenosed, or occluded intracranial vessels, collaterals to locate an arterial obstruction and refine carotid-duplex or noninvasive angiographic findings; vasomotor reactivity testing to identify high-risk patients for first-ever or recurrent stroke; emboli detection to detect, localize, and quantify cerebral embolization in real time; RLS-detection in patients with suspected paradoxical embolism or those considered for shunt closure; monitoring of thrombolysis to facilitate recanalization and detect reocclusion; monitoring of endovascular stenting, carotid endarterectomy, and cardiac surgery to detect perioperative embolism, thrombosis, hypo- and hyper- perfusion.

The article summarizes established clinical indications, frequency of testing, and expected outcomes. In short, the article describes that TCD has been shown to provide diagnostic and prognostic information that determines patient management decisions across multiple cerebrovascular conditions and periprocedural/surgical monitoring.

The Value of TCD

Due to a continuous registration of blood flow, TCD offers an excellent temporal resolution in comparison to other neuroimaging techniques. The technique is noninvasive and easy to apply, while blood flow measurements are robust against movement artifacts. In conclusion, since its introduction fTCD has contributed substantially to the elucidation of the hemispheric organization of cognitive, motor, and sensory functions in adults and children. In summary, TCD provides a noninvasive and inexpensive (relative to angiography) monitoring modality that can be used in a variety clinical situation to provide real-time physiological information that is often unobtainable with other testing without increasing patient risks (repeated radiation doses, contrast injections) and associated costs.

Transcranial Doppler (TCD) is a physiological ultrasound test with established safety and efficacy. Although imaging devices may be used to depict intracranial flow superimposed on structural visualization, the end-result provided by imaging duplex or nonimaging TCD is sampling physiological flow variables through the spectral waveform assessment.