Power-based versus conventional transcranial color-coded duplex sonography in the assessment of the vertebrobasilar-posterior system

Abstract

Power Doppler (PD) is a new ultrasonic technique that allows improved visualization of vascular structures. The aim of our study was to compare the ability of power-based transcranial color-coded duplex sonography (p-TCCS) to conventional transcranial color-coded duplex sonography (TCCS) and contrast-enhanced transcranial color-coded duplex sonography (CE-TCCS) in the visualization of the vertebrobasilar system. In 41 patients without cerebrovascular diseases, we evaluated and compared identification rates of major vessels of the vertebrobasilar system and branches using both ultrasound (US) techniques. In 9 patients we performed additional CE-TCCS studies. Furthermore, the possibility of visualization of the basilar artery (BA) and the vertebral arteries (VA) over the long course was investigated. TCCS and p-TCCS were equally effective at showing the VAs (74 of 82 v 80 of 82), proximal segments of the BA (37 of 41 v 41 of 41) and P1 segments of the posterior cerebral artery (PCA) (72 of 82 v 82 of 82). However, the diagnostic sensitivity of p-TCCS was significantly better for peripheral segments of the PCA (34 of 82 v 68 of 82 for P2 and 2 of 82 v 24 of 82 for P3 segments, P<.001), distal parts of the BA (25 of 41 v 38 of 41, P<.01), the anterior inferior cerebellar artery (AICA) (0 of 82 v 8 of 82, P<.0001) and the posterior inferior cerebellar artery (PICA) (13 of 82 v 34 of 82, P<.001). Furthermore, using transtemporal coronal sections, p-TCCS allowed visualization of the BA over the complete course in connection with one or both VAs in half of the patients. Except P2 and P3 segments, CE-TCCS did not increase resolution compared with p-TCCS. PD offers significant advantages over color-coded sonography in imaging the BA and small-calibre vessels like the PICA, AICA, and peripheral segments of the PCA. P-TCCS in combination with TCCS increases the diagnostic sensitivity to identify vascular structures of the vertebrobasilar system.