Vertebrobasilar Transcranial Color-Coded Duplex Ultrasonography: Improvement with Echo Enhancement

Abstract

BACKGROUND AND PURPOSE: The diagnostic yield of vertebrobasilar transcranial color-coded duplex ultrasonography (US) is often hampered by insufficient acoustic penetration, anatomic variations, and vessel tortousity. The purpose of this study was to evaluate the effect of echo enhancement on vertebrobasilar transcranial color-coded duplex US.

METHODS: In 23 consecutive patients (mean age, 61.0 ± 11.1 years) with vertebrobasilar stroke, the vertebrobasilar system (P1 segment of the posterior cerebral artery [PCA], basilar head, V4 segment of the vertebral artery, and basilar artery) was examined with transcranial color-coded duplex US before and after injection of an echo-enhancer. The acoustic window was graded according to visibility of parenchymal structures, and vessel imaging was graded according to the appearance of the color mode signal. Maximum depth of the basilar color signal was recorded. All patients with an abnormal or inconclusive US finding underwent either digital subtraction angiography or MR angiography.

RESULTS: In the P1 PCA, V4 vertebral artery, basilar artery, and basilar head, image quality was insufficient in 65%, 82%, 83%, and 38%, respectively, before echo enhancement, and in 15%, 30%, 35%, and 9%, respectively, after echo enhancement. In all graded vessels, the improved image quality with echo enhancement was statistically significant. Compared with the reference examinations in the 15 cases of occlusion or stenosis, definite diagnosis was possible in 60% (nine cases) with nonenhanced transcranial color-coded duplex US and in 93% of (14 cases) after echo enhancement.

CONCLUSION: Echo enhancement resulted in improved image quality of the vertebrobasilar system and markedly increased diagnostic confidence.