Color duplex ultrasonography of the intracranial vertebro-basilar system: improved imaging by echo signal enhancement

Abstract

Transcranial colour-coded duplex sonography allows differentiation of both vertebral arteries and the proximal basilar artery by transoccipital insonation. However, imaging is often incomplete. Therefore the aim of this study was to show to what extent imaging of vertebrobasilar arteries can be improved with the use of the echosignal enhancing agent Levovist (LV) in normal subjects without vascular abnormalities or occlusive disease. In 30 subjects extracranial Doppler and duplex sonography has been used to exclude hypoplasia and proximal or distal obstructions of the vertebral arteries. The intracranial vertebral arteries and the basilar artery were then examined before and after fractionated injection of LV (300 mg/ml, 4 g) by means of colour-coded transoccipital duplex sonography including videorecording. Without LV only 17 of 90 possible segments could be imaged completely (basilar artery and both vertebral arteries in 30 subjects). After LV 72 of 90 possible segments could be demonstrated. The confluence of the vertebral arteries could be localised in 22 of 30 subjects by means of LV. The average depth was 6.7 cm (5.5 to 8 cm). Additionally branches of the main arterial trunks could be imaged. The basilar artery could be followed up to a depth of 10 cm. In most cases the distal part of the basilar artery could not be evaluated not even by means of LV enhancement. Imaging of the vertebrobasilar arteries including the proximal basilar artery could be definitely improved by means of echosignal enhancing Levovist. Imaging of the distal basilar artery was not satisfactory. The confluence of the vertebral arteries could not be precisely localised in all cases due to the course of the arteries.