A novel method for the assessment of the accuracy of computing laminar flow stroke volumes using a real-time 3D ultrasound system: In vitro studies.
OBJECTIVE
Laminar flow stroke volume (SV) quantification in the ascending aorta or pulmonary artery can provide a measure for determining cardiac output (CO). Comparing flows across different valves can also compute shunt volumes and regurgitant fractions. Quantification methods for 3D color Doppler laminar flow volumes have been developed using reconstructive 3D, but these are cumbersome and time-consuming both in acquisition and measurement. Our study evaluated newly developed color Doppler mapping with real-time live 3D echo to test velocity, spatial and temporal resolution for computing SV.


RESULTS
Five rubber tubes (diameters=3.0, 2.25, 2.0, 1.9, 1.7 cm), a freshly dissected porcine aorta (Ao) and a pulmonary artery (PA) (both 2-3 cm diameter) were connected to a pulsatile pump in a water bath. Different SV, from 10 to 80 ml/beat, were studied at pump rates of 40-60 bpm in this phantom model with flow quantified by timed collection. The Nyquist limit was set between 43 and 100 cm/s and frame rate ranged from 14 to 23/s. ECG triggered 3D color Doppler volumes were acquired with a 2-4 MHz probe. The digital scan line data from the 3D volumes, with retained velocity assignments, was exported and analyzed offline by MatLab custom software. Close correlations were found between 3D calculated SV and reference data for all tubes (r=0.98, y=1.14x-1.69, SEE=2.82 ml/beat, p<0.0001). Both Ao and PA flows were also highly correlated with the reference measurements (PA: r=0.98, SEE=3.17 ml/beat; Ao: r=0.99, SEE=3.20 ml/beat).


CONCLUSIONS
Real-time 3D color Doppler method could provide an efficient, accurate and reliable method for clinical evaluation and quantification of flow volumes in patients.
Li
Xiaokui
X
Oregon Health & Science University, Portland, OR 97239, USA.
Ashraf
Muhammad
M
Thiele
Karl
K
Bhat
Aarti Hejmadi
AH
Sakaguchi
Ron
R
Mitchell
John C
JC
Brie
Julie A
JA
Young
Monica
M
Bader
Rima S
RS
Pemberton
James
J
Sahn
David J
DJ
D000818:Animals; D001011:Aorta / Q000000981:diagnostic imaging / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D018618:Echocardiography, Doppler, Color / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D019560:Echocardiography, Three-Dimensional / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D066298:In Vitro Techniques; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D015588:Observer Variation; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000502:physiology; D013318:Stroke Volume / Q000502:physiology*; D013552:Swine