Can transcranial Doppler really detect reduced cerebral perfusion states?

Area of Science:

• Neurology
• Vascular Medicine
• Medical Imaging

Background:

• Cerebral atherosclerosis and arteriolosclerosis are common in patients with hypertension or diabetes.
• Assessing reduced brain perfusion in these patients is crucial for managing cerebrovascular disease risk.

Purpose of the Study:

• To evaluate the utility of transcranial Doppler ultrasonography (TCD) in detecting reduced brain perfusion states.
• To assess TCD's ability to identify hemodynamic abnormalities in patients with hypertension or diabetes and suspected cerebral atherosclerosis/arteriolosclerosis.

Main Methods:

• Blood flow velocity in the middle cerebral artery and cerebrovascular vasodilator responses to carbon dioxide were measured using TCD in 22 patients.
• Positron emission tomography (PET) was used to measure cerebral blood flow and oxygen metabolism for comparison.
• Patients had or did not have carotid artery occlusive disease and minor stroke.

Main Results:

• TCD-measured blood flow velocity strongly correlated with PET-measured ipsilateral cerebral blood flow across multiple brain regions and the entire hemisphere.
• Relative changes in TCD-measured blood flow velocity and cerebrovascular resistance correlated closely with regional mean transit time.
• TCD variables did not correlate with PET-measured hemispheric oxygen metabolism.

Conclusions:

• Transcranial Doppler ultrasonography is valuable for detecting cerebral hemodynamic abnormalities in patients at risk for cerebrovascular disease.
• TCD is not suitable for assessing impairments in cerebral metabolism.
• TCD aids in identifying reduced perfusion states in patients with hypertension or diabetes.