Transcranial Doppler Ultrasound Recording of Flow Velocity in Basal Cerebral Arteries: Examination Technique and Normal Values in Korean

ABSTRACT

We present the examination technique and normal values of flow velocity from intracranial basal cerebral arteries for a recently developed pulsed Doppler system operating at 2 MHz emitting frequency. Peak systolic, peak diastolic, and mean flow velocity values are analyzed from fast-Fourier transformed(FFT) Doppler spectra at selected depths for 50 presumed normal subjects ranging in age from 18 to 72 years. Interindividual variation is high for peak flow but moderate for mean flow velocity values, which hence are more likely to discriminate normal from abnormal. Flow velocity values within the posterior cerebral attery(PCA) and the basilar artery(BA) are significantly lower than in the anterior cerebral artery(ACA) and the middle cerebral artery(MCA), which is also unique in showing significantly decreasing values with increasing age. Calculated mean flow velocities are 61+/-14 cm/s in the middle cerebral artery(MCA) and 51+/-14 cm/s in the anterior cerebral artery(ACA), and 45+/-11 cm/s in the posterior cerebral artery(PCA) through the temporal window and 43+/-14 cm/s in the basilar artery through the suboccipital window and 15+/-5 cm/s in the ophthalmic artery and 47+/-13 cm/s in the internal carotid artery(lCA) through the transorbital window. A new scanning system is introduced, which we suggest will reduce interindividual variations and improve the accurate separation of nearby vessels, which are major causes of the comparatively large standard deviations at present.