Duplex ultrasonographic insonation and visualization of intracerebral arteries.

Until now, clinical, noninvasive interrogation of intracranial vessels has consisted only of insonation via transcranial Doppler. Such devices have utilized a 2.0 MHz, continuous wave probe with Doppler spectral waveform display. Clincial aapplication 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 intracranial arterial visualization has limited the clinical pplicability 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 perfomred simultaneously and along the entire visible artery 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 on intracerebral vessels. The ability to visualize and insonate simultaneously eliminates the uncertainty caused by anatomic variation. These advantages, long applied to the evaluation of peripheral vessels, are now available for use in the diagnosis of intracranial arterial disease.

Comparison of duplex ultrasonography and ascending contrast venography in the diagnosis of venous thrombosis.

The application of duplex ultrasonography to the diagnosis of venous thrombosis requires validation by comparison of the duplex findings with the results of ascending contrast venography. In this study, 2534 veins were examined by both methods with contrast venography results serving as the standard for comparison. In this setting, duplex ultrasonography proved to be 100% sensitive and 99% specific for venous thrombosis. Duplex ultrasonography is as reliable as venography in the diagnosis of venous thrombosis and has no associated risks or known complication. In addition, duplex ultrasonography provides information regarding pathologic anatomy that is comparable to the detail provided by high-quality venography. The authors conclude that duplex ultrasonography should be the diagnostic method of choice for evaluating patients with suspected venous thrombosis.