DECORRELATION OF INTRAVASCULAR ECHO SIGNALS - POTENTIALS FOR BLOOD VELOCITY ESTIMATION

When blood particles travel through an intravascular ultrasound imagin g plane, the received echo signals decorrelate at a rate that is relat ed to the flow velocity. In this paper, the feasibility of extracting blood velocity from the decorrelation function of radio frequency sign als was investigated through theoretical analysis and computer simulat ion. A computer model based on the impulse response method was develop ed to generate the ultrasound field of a 30-MHz intravascular transduc er. The decorrelation due to the scatterer displacement as well as oth er nonmotion related decorrelation sources were studied. The computer simulations show that the decorrelation function is linearly related t o the lateral displacement. The monotonic relationship between correla tion and displacement provides possibilities to estimate flow velocity with decorrelation measurements. Because of the complexity of the bea m profile in the near field, assessment of local velocities requires d etailed knowledge of the decorrelation at each axial beam position. So urces of signal decorrelation other than the lateral displacement may cause a bias in the decorrelation based velocity measurements. For loc alized decorrelation estimation, measurement variations in small range windows present a major challenge. An approach based on multiple deco rrelation measurements should be adopted in order to reduce the variat ions. In conclusion, results of this study suggest that it is feasible to measure flow velocity by quantifying the decorrelation of intravas cular ultrasound signals from blood. (C) 1997 Acoustical Society of Am erica. [S0001-4966(97)00612-7].