Abstract:
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Purpose: It is generally assumed that the angle correct can make up for any angle that the transducer beam makes with the vessel wall to determine the flow velocities in, for example, the carotid artery. To compare velocities in the common carotid artery calculated by using the Doppler angle correct set at 44 and 60 degrees (by heel-toeing the transducer) to see if there is any consistent difference in the velocity values.
Methods and Materials: A total number of 15 patients with normal hemodynamic flow pattern in carotid arteries and no obvious plaque disease were selected. Each patient was examined by two sonographers who did not know the results from the other sonographer. The peak systolic velocities of both right and left mid common carotid arteries were measured three times with the angle correct set at 44 degree and three times at 60 degree. The heel-toe technique was used to get the artery parallel with the angle correct set at 44 and 60 degrees. Intra and inter observer errors were calculated in addition to average and standard deviations for the results obtained at 60 versus 44 degree.
Results: A total number of 360 peak systolic velocities of CCA were obtained. All the measurements with the Doppler angle of 60 degree were increased compared to the measurements obtained at 44 degree. The average velocity of the right CCA was 97 cm/sec with a standard deviation of 21 cm/s at 60 degree and 76 cm/sec with a standard deviation of 16 cm/s at 44 degree, a significant difference of 21 cm/sec or 27%. Similar results were achieved on the left CCA. The average velocities of the left CCA were 99cm/sec with a standard deviation of 19 cm/s at 60 degree compared to 80 cm/sec with a standard deviation of 17 cm/s at 44 degree, a significant difference of 19 cm/sec or 24%. Also the PW spectral Doppler obtained at 44 degree showed a stronger Doppler signal (trace and sound) as well as a good color filling compared to the 60 degree angle.
Conclusion: A Doppler angle of 60 degree will increase the velocity values significantly compared to 44 degree and this may require a new comprehensive study to compare the velocities in the stenotic ICA at 44 vs 60 degree with resultant changes in the ICA/CCA ratio in relation to the NASCET classification for the carotid stenosis. The Doppler angle is critical in correctly quantifying flow velocities in order to categorize the severity of the carotid disease. The potential explanations for this phenomenon as well as the detailed statistical data will be presented.
Questions about this event email: htahmasebpour@yahoo.ca
Tahmasebpour, H,
Velocity Quantifications in the Carotid Ultrasound with Doppler Angle Set at 44 vs 60 Degree. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3102227.html
