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CW Sheets, A Harris, C Cole, C Pesavento, L Kagemann, FH Orge; Accuracy of Volumetric Flow and Flow Velocity Measurements with ATL Ultrasound in an In-vitro Model . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4371.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the accuracy of ATL HDI-5000 color Doppler imaging (CDI) measurements of volumetric blood flow and velocity in a well-controlled model with known flow. Methods: A phantom flow model was constructed using agarose gel to mimic fatty soft tissue. 1.57mm and 2.36mm diameter lumens were created in the gel. A UHDC flow system pumped blood-mimicking fluid through each tube at low, medium, and high rates. The ATL HDI-5000 measured the velocity and volumetric flow in the phantom model using cineloops (a cineloop is a rapidly acquired sequence of CDI images). A newly developed software package from ATL calculated volumetric flow from the cineloops. Measurements were performed with the probe in four different positions: 1) 45° angle, parallel to the flow, 2) 45° angle, offset to the flow, 3) 75° angle, parallel to the flow, and 4) 75° angle, offset to the flow. A 95% confidence interval was calculated for flow measurement. The measurement was considered accurate if the confidence interval contained the true mean. Results: Only 7 of 24 trials provided accurate flow. Fourteen trials erred with high measurements, and 2 erred with low measurements. The ATL cineloop analysis of volumetric flow provided 5 accurate measurements with the probe positioned parallel to the vessel as opposed to 2 accurate measurements with the probe at an angle to the flow (offset). Velocity measurements from the cineloops were more accurate with 12 of 24 providing accurate values. The ATL cineloop analysis of flow velocity provided 11 accurate measurements with the probe positioned at an angle to the vessel (offset) as opposed to 1 accurate measurements with the probe parallel to flow. All 6 measurements with the probe at a 45 degree angle and offset were accurate. Also, 11 trials erred with low measurements while 1 erred with a high measurement. Conclusion: Cineloop measurements of volumetric flow and velocity are theoretically possible and sometimes accurate. However, the velocity measurements are considerably more accurate than flow. This suggests that the problem with the ATL software lies in its calculation of diameter rather than velocity.
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