Angle Correction in Transcranial Doppler Sonography

摘要: Since the introduction of transcranial Doppler sonography in early 1980s, flow velocity estimates have assumed a 0- to 30-degree angle insonation. Based on limited radiological and anatomical studies, such as assumption appeared justified, seemed confer only minimal potential for error due cosine function formula. The color duplex allows direct evaluation this effect velocities. Fifteen healthy volunteers were studied bilaterally using unilateral transtemporal approach from right. Velocity measurements taken middle, anterior, posterior cerebral arteries. Flow velocities obtained with without correction (0 degree). After completion study, conventional, "blind" transducer at corresponding depths. For all insonated vessels average insonation was around 30 degrees. However, there wide variability individual angles (0-70 degrees) specific vessels. In 74.5% vessels, angle-corrected did not exceed uncorrected by more than 25%. 14.5% 25 50% higher 10.8% it compared velocity. Thus, unpredictable often originally expected. Angle-corrected values, 25% about one-fourth studied. Understanding clinical importance differences requires further study.