Transcranial Doppler sonography: anatomical landmarks and normal velocity values

Area of Science:

• Neuroimaging
• Vascular Neurology
• Ultrasound Technology

Background:

• Intracranial occlusive disease and flow abnormalities were previously difficult to diagnose with ultrasound.
• The development of transcranial Doppler sonography (TCD) has opened new possibilities for studying the intracranial vasculature.

Purpose of the Study:

• To establish anatomical landmarks and flow characteristics of intracranial vessels for accurate TCD interpretation.
• To provide normative data for TCD measurements in healthy individuals and patients.

Main Methods:

• Data were collected from carotid and vertebral angiograms, CT scans of the Circle of Willis, MRI scans, cadaver studies, and TCD measurements in volunteers and patients.
• Insonation depths and mean flow velocities of specific intracranial arteries were measured and analyzed.

Main Results:

• Specific insonation depths were identified for key intracranial artery segments (e.g., internal carotid artery bifurcation, MCA M1-segment, basilar artery).
• Normal mean flow velocities were established for several major intracranial arteries, showing a decrease with age.
• Vertebrobasilar data from imaging correlated well with in vivo TCD findings.

Conclusions:

• The study provides essential anatomical and hemodynamic data for accurate TCD examinations.
• Established criteria aid in identifying intracranial vessel segments and differentiating normal from pathological flow.
• These findings are crucial for training new TCD users and improving diagnostic accuracy for cerebrovascular diseases.