Effect of Spatial, Temporal, and Velocity Resolution on Doppler Tissue Image Derived Indices
Many indices derived from color Roppler Tissue Imaging (UTI) are computed mathematically from the velociy fields provided by the ultrasound scanner We developed a procedure for assessing the uncertainty that temporal, spatial, and velociry resolution causes on cardiovascular parameter5 derived from myocardial velociry. A first-order Taylor's series for the functional relationship between velocity and the cardiac index under study is proposed, and analytically solved by using the chain rule. Pedormance on myocardial acceleration, strain, and strain rate, was tested both on a simulation model (symbolic calculations) and on a clinical image example. Velociry and temporal resolutions were the most determinant on DTI-derived parameters, and increasing color-Doppler bit-depth from 5 to 7 bils reduced to less than 10% the uncertainty of all the analyzed indices. Taylor-based error bounds are a useful tool tu assess the effect of resolution on quantitative cardiovascular indices derived from tissue velocity measurements.