Lm. Wang et Kk. Shung, ADAPTIVE PATTERN CORRELATION FOR 2-DIMENSIONAL BLOOD-FLOW MEASUREMENTS, IEEE transactions on ultrasonics, ferroelectrics, and frequency control, 43(5), 1996, pp. 881-887
One of the major drawbacks of ultrasonic Doppler instruments in measur
ing blood flow is their inability to measure the velocity perpendicula
r to the beam, Time domain RF echo or speckle tracking has been studie
d as an alternative to overcome this problem. By acquiring two-dimensi
onal (2-D) echo signals, both lateral (perpendicular to the beam) and
axial (parallel to the beam) velocities can be calculated with 2-D pat
tern correlation algorithms, One of the disadvantages of the current 2
-D pattern correlation algorithms is the extensive computation time in
volved in computing the 2-D cross-correlation function, In this paper,
we present several time-efficient bit-pattern correlation algorithms
to execute 2-D speckle tracking. The proposed algorithms first estimat
e the noise level from the acquired signals and use it as a priori kno
wledge to minimize computation time. The reduction of computation time
may make it more feasible for real-time measurements of how velocitie
s in two dimensions, Radio frequency and video data collected from two
commercial scanners are used to validate the feasibility of these pro
posed algorithms with porcine blood as the flowing medium in in vitro
experiments. The results obtained by the proposed algorithms are in go
od agreement with those computed from the crosscorrelation function.