Aggregation of red cells and linear velocity gradients: influence on the correlation-based method for quantitative IVUS blood flow at 20 MHz

Recent computer simulations suggest that the presence of aggregates of red blood cells (RBCs), at random angles and lengths, does not affect the measurements of transverse blood flow using a correlation-based method and an IVUS array catheter. Blood velocity gradients were also shown not to influence the correlation-based method for blood velocity estimation. The objective of this study is to quantify the influence of aggregates of RBCs and blood velocity gradients on the correlation-based method during in vitro experiments. For this purpose, measurements were performed on normal and diseased human blood. The decorrelation pattern of a circular ultrasound transducer as a function of transverse blood flow was studied using a Couette system. Agreements were found between the auto-convolution of the acoustical beam and the RF decorrelation patterns.