Measurement of blood flow velocity in the basal cerebral circulation: advantages of transcranial color-coded sonography over conventional transcranial Doppler.

Unlike conventional transcranial Doppler (TCD), transcranial color-coded sonography (TCCS) enables imaging of the basal cerebral arteries using color-flow ultrasonography and correction for the angle of insonation when determining blood flow velocities. We present hemodynamic data from 20 normal subjects, each studied with TCD and TCCS. Velocities derived using TCCS with angle correction were significantly greater than those derived using TCD in all vessels (mean velocities [cm/sec; mean with 95% confidence intervals)--anterior cerebral artery: TCD 48 (45-50), TCCS 62 (58-66), p < .0001; middle cerebral artery: TCD 61 (58-64), TCCS 70 (66-74), p < .0001; posterior cerebral artery: TCD 43 (41-46), TCCS 54 (50-57), p < .0001; basilar artery: TCD 40 (34-45), TCCS 45 (38-52), p < .01. Pulsatility index values were significantly greater in all arteries when determined by TCCS, and resistance index values were significantly greater except in the basilar artery. Correcting for the angle of insonation using TCCS may enable estimation of blood flow velocities closer to the "true" values than those derived using conventional TCD.