J Korean Soc Med Ultrasound.  1998 Dec;17(4):365-373.

Semi-quantitative Assessment of Collateral Flow Through the Circle of Willis by Contrast-enhanced Transcranial Doppler Ultrasonography(TCD): Comparison with Digital Subtraction Angiography(DSA)

• Lee YJ
• Chung TS
• Joo JY
• Lee MS

Abstract

PURPOSE: The preoperative evaluation of the collal flow through the circle of Willis is necessary for the certain cases such as intracranial aneurysms or head and neck tumors which sometimes need ligation of internal carotid artery. So we intended to evaluate collateral flow through the circle of Willis semi-quantitatively by transcranial Doppler ultrasonography (TCD) using Levovist(R) for the purpose of replacing invasive digital subtraction abgiography(DSA). MATERIALS & METHODS: Twenty-two TCD examinations with bolus injection of Levovist (Schering AG, Germany) on 20 patients with central nervous system diseases were undertaken with color Doppler machine(128XP/10, Acuson, USA). All of them had taken DSA. We compared the results of TCD with those of DSA in finding out the presence and the amount of collateral flow through the circle of Willis. We also compared the change(minimal decrease, marked decrease, complete loss) of color Doppler signal intensities(SI) with decrease ( < or > or =65%) of mean middle cerebral artery (MCA) flow velocity before and during compression of ipsilateral common carotid artery (CCA) on TCD.
RESULTS
TCD coincided with DSA in finding out the presence of collateral flow through anterior communicating artery (AcoA) except 2 patients with extremely poor transmittance of acoustic window. TCD, however, could not detect collateral flow through posterior communicating artery (PcoA) execpt 1 patient with fetal type PcoA. TCD depicted 4 cases with insufficient amount of collateral flow from 12 cases which showed good collateral flow through AcoA in DSA. On TCD, the cases with minimal decrease of color Doppler SI(n=8) during compression of ipsilateral CCA also showed decrease of mean MCA flow velocity less than 65% which means sufficient amount of collateral flow.
CONCLUSION
Semi-quantitative assessment of the amount of collateral flow could be done by checking the changes of mean flow velocity and color Doppler SI of MCA by TCD, and TCD can replace DSA for the functional evaluation of collateral flow through the circle of Willsi.

MeSH Terms

Acoustics
Arteries
Carotid Artery, Common
Carotid Artery, Internal
Central Nervous System Diseases
Circle of Willis*
Head
Humans
Intracranial Aneurysm
Ligation
Middle Cerebral Artery
Neck
Ultrasonography, Doppler, Transcranial