Measurement of Common Carotid Flow Volume by Ultrasonic Quantitative Flow Measurement System

—Accuracy and physiological variation—

Abstract

Ultrasonic quantitative flow measurement system (QFM) was developed to measure an absolute flow volume of common carotid artery (CCA) noninvasively as one of the cerebral circulation tests. It is verified from the model experiment that the output is independent of the depth of vessel and the angle between beam and flow. Moreover, the accuracy is confirmed by the comparison with the electromag-netic flow meter; the error is less than ±7%. However, it is required for accurate and reproducible measurements to handle the probe properly to detect an adequate amplitude of wall echo and to set the gate position at the vessel inner surface echo. The following clinical results have been obtained: 1) There is no significant difference in CCA flow volume between right and left sides. 2) The mean value of male/female is 1.058. 3) The CCA flow volume is decreased with age: 8.98ml/s in 20s and 8.03ml/s in 70s. 4) Body position : The rapid standing from supine position decreases the CCA flow volume; the ratio ranged from -3.3% to -22.2%. 5) It is suspected that the CCA flow is independent of the blood pressure. 6) CCA flow volume in sleeping stage decreases 10% in REM and 20% in non-REM.