Quantitative blood flow estimation error due to the in-plane component of the flow with intravascular ultrasound

Previously, we presented a method to measure blood flow perpendicular to the imaging plane in real time with an intravascular ultrasound (IVUS) imaging system using a slow-time FIR (finite impulse response) filter bank. The presence of an in-plane component when the flow direction is not exactly perpendicular to the imaging plane introduces an error in the flow measurement using the filter bank algorithm. Flow speed is estimated as a function of the slow-time spectral energy inside the frequency bands of each FIR filter. When the flow direction is not perpendicular to the imaging plane, flow speed is overestimated as the energy within those bands increases. We present a variation of the FIR filter bank algorithm, applying filter coefficients in a tilted fashion to slow-time signals (i.e., combining slow-time and fast-time). Independent simulations were performed and the behavior of the new algorithm was quantified. Results demonstrate the potential use of this algorithm to correct flow speed overestimates due to in-plane component corruption.