Pressure gradient determination by three dimensional Doppler ultrasound using a modified Bernoulli equation

Three-dimensional Doppler ultrasound was used to determine pressure gradients in an in vitro model of a velocity jet. Doppler velocity determinations were within 3.85% of actual velocities, and the pressure gradients predicted by these velocities were within 2.85% of the pressures predicted by the Bernoulli equation. A proposed modification of the Bernoulli equation was used to account for the differences between pressures predicted by the theoretical Bernoulli equation and the actual measured pressures, which varied by as much as 16.86%. The modified Bernoulli equation contains a first-order term in velocity, derived from the Navier-Stokes equations, to estimate the frictional loss in a circular tube. The application of a modified Bernoulli equation is discussed for predicting degree of stenosis in clinical applications.<>