Transcranial Doppler Ultrasonography as a Diagnostic Tool for Cerebrovascular Disorders

Abstract

Imaging techniques including transcranial Doppler (TCD), magnetic resonance imaging (MRI), computed tomography (CT), and cerebral angiography are available for cerebrovascular disease diagnosis. TCD is a less expensive, non-invasive, and practically simpler approach to diagnosing cerebrovascular disorders than the others. TCD is a commonly available and inexpensive diagnostic tool. However, owing to its large operator dependency, it has a narrow application area. Cerebrovascular disease indicates a group of disorders that alter the flow of blood in the brain. The brain's functions can be temporarily or permanently impaired as a result of this change in blood flow. Timely diagnosis and treatment can restore the brain-impaired functions, resulting in a much-improved prognosis for the patients. This review summarizes the basic principles underlying the TCD imaging technique and its utility as a diagnostic tool for cerebrovascular disease.

Keywords: TCD; blood flow; cerebrovascular disease; neurological condition; non-invasive.

FIGURE 1

Panel (A) indicates ultrasonic probes, with blue arrows indicating TCD and yellow arrows indicating Transcranial color-coded sonography (TCCS). Panels (B–D) show transcranial acoustic windows used in TCD evaluation, including transorbital, suboccipital, and transtemporal windows, accordingly (Bathala et al., 2013).

FIGURE 2

Measurement of the cerebral blood flow velocity (CBFV) in the MCA by TCD. The Circle of Willis and the MCA can be seen when the 2 MHz probe is positioned transtemporally. The ACA and PCA can be insonated by TCD as well (D’Andrea et al., 2016a).

FIGURE 3

Typical transtemporal window parameters used in TCD imaging (Naqvi et al., 2013).

FIGURE 4

In clinical practice, simplified algorithms for evaluating brain death, intracranial hypertension, cerebral vasospasm, and autoregulation using TCD. PI indicates pulsatility index while Vd, Vm, and Vs indicate diastolic flow, mean flow, and systolic flow velocity, accordingly (Robba and Taccone, 2019). While LR represent the lindegaard ratio, and CCA represent cerebral circulatory arrest. * The three reported images represent reverberating flow (top), systolic pikes (middle), and no flow (bottom), respectively (Robba and Taccone, 2019).