Michael Y. Park MD, Presenter: Nothing to Disclose

Seung Eun Jung MD, Abstract Co-Author: Nothing to Disclose

Jae Young Byun MD, Abstract Co-Author: Nothing to Disclose

Gaeul Joo, Abstract Co-Author: Nothing to Disclose

June Hoan Kim MS, Abstract Co-Author: Nothing to Disclose

Sung Hoon Kim, Abstract Co-Author: Nothing to Disclose

To examine the effect of different beam-flow angles on the accuracy of Doppler ultrasound measurements in modern ultrasound systems

A flow phantom was used to create a steady flow of water in a 4.3 mm diameter tube. Using three different modern university grade ultrasound systems, flow was measured at 30, 40, 50, 60, 70, 80, and 88 degree beam-flow angles twice using a convex and linear probe. Measured flow ratio (MFR) defined as measured velocity divided by estimated actual velocity was calculated. Intraprobe, interprobe, and intermachine mean variation of MFR were calculated.

MFR showed an increase as beam-flow angles increased. MFR for the angles 30, 40, 50, 60, 70, 80, and 88 degrees were 0.90, 0.97, 1.1, 1.2, 1.6, 2.3, and 10.2, respectively. Intraprobe, interprobe, and intermachine variation did not show marked differences. For angles grouped as 30-40, 50-60, 70, and 80-88 degrees, intraprobe variation was 12.3%, 15.1%, 14.7%, and 25%; interprobe mean variation was 12.3%, 15,1%, 14.6%, and 25.9%; and intermachine variation was 16.1%, 16.2%, 16.7%, and 54.2%, respectively. As beam-flow angle increased, an increase in spectral broadening was also noted.

There is no simple cutoff beam-flow value such as the well quoted less than 60 degrees, where measurements can be considered accurate. For follow up imaging, beam-flow angles differences should be considered and the same beam-flow angles should be used when possible.

There is no simple cutoff beam-flow value such as less than 60 degrees for accuracy, and similar beam-flow angles for Doppler velocity measurement follow-up is important.

Park, M, Jung, S, Byun, J, Joo, G, Kim, J, Kim, S, Effect of Beam-Flow Angle on the Accuracy of Modern Doppler Ultrasound Systems.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11006778.html