Duplex Ultrasonographic Insonation and Visualization of Intracerebral Arteries

Abstract

Until now, clinical, noninvasive interrogation of intracranial vessels has con sisted only of insonation via transcranial Doppler. Such devices have utilized a 2.0 MHz, continuous wave probe with Doppler spectral waveform display. Clinical application of these techniques has required precise location of cranial "windows" and has been hampered by the extreme anatomic variability of both cranial bony structures and intracerebral arteries. The lack of simultaneous in tracranial arterial visualization has limited the clinical applicability of transcranial Doppler technology.

Recently, the authors have utilized a 2.25 MHz curved phased array probe with a pulsed Doppler to image and insonate simultaneously the intracerebral arteries. Colorflow imaging of both near- and far-field regions is the necessary first step for vessel localization and identification. Once this is accomplished, the image of each artery in turn is amplified and gray scale tuning is employed to permit direct visualization of the arterial walls and lumen. Pulsed Doppler waveform analysis is performed simultaneously and along the entire visible ar tery length. In this manner the arteries of both right and left hemispheres are examined in detail.

We have found the duplex technique to be superior to the use of Doppler alone in the examination of intracerebral vessels. The ability to visualize and insonate simultaneously eliminates the uncertainty caused by anatomic varia tion. These advantages, long applied to the evaluation of peripheral vessels, are now available for use in the diagnosis of intracranial arterial disease.