ULTRASONIC ESTIMATION OF TISSUE PERFUSION - A STOCHASTIC APPROACH

Imaging of blood flow perfusion is an area of significant medical inte rest, Recently, the advantages of using the total integrated Doppler p ower spectrum as the parameter that is encoded in color has been shown to result in an approximately threefold increase in flow sensitivity, a relative insensitivity to acquisition angle and lack of aliasing, W e have taken this mode a step further and demonstrated the potential f or quantifying blood flow using correlation-based algorithms applied t o the power signal, We show that Phi(tau) = Phi(0)e(-nu tau), tau > 0, where Phi(tau) is the two-time correlation of the fluctuation in the power signal, and nu is the specific flow (reciprocal of mean transit time), Scans of a dog's blood, pumped at a constant rate through gum r ubber tubing, were obtained using a Diasonics Spectra 10-MHz linear ar ray transducer at standard range-gated spectral mode (PRF = 1400 Hz, w all filter = 50 Hz, sample gate = 1.5 mm), A fixed Doppler angle of 68 degrees was used, Five different flow rates were tested, and the velo cities determined by power decorrelation were compared to the mean vel ocities calculated from the Doppler shifts by linear regression (R(2) = 0.987), We believe the results are very encouraging for using power decorrelation in perfusion evaluation.