Analysis of mitral regurgitation from slit orifices by ultrasonic imaging
An ultrasonic diagnostic imaging system is described which quantifies regurgitant flow through a plurality of pinhole leaks or a slit leak of a mitral valve. A plurality of orifice locations of a leaking valve are identified and Doppler values obtained from a flow velocity field proximal each orifice. The Doppler values of each flow velocity field vectorially relating to the orifice location are processed to produce a measure of flow through the orifice. The flow measurements for a plurality of such orifices are summed to produce a quantified measure of regurgitant flow through a plurality of pinhole leaks or along a slit leak.
1. A method for measuring regurgitant flow from multiple or slit orifices, the method comprising:
selecting a first orifice location in a heart;
transmitting, by an ultrasound system, ultrasonic waves toward the first orifice location;
acquiring, by the ultrasound system, ultrasonic echo signals in the vicinity of the first orifice location;
processing the echo signals to produce a vector velocity field of regurgitant flow through the first orifice location;
selecting a second orifice location in the heart;
transmitting ultrasonic waves toward the second orifice location;
acquiring ultrasonic echo signals in the vicinity of the second orifice location;
processing the echo signals to produce a vector velocity field of regurgitant flow through the second orifice location,
wherein the processing the echo signals to produce the vector velocity fields of regurgitant flow through the first and second orifice locations comprises:
generating starting values for the vector velocity field of regurgitant flow through the first or second orifice location with a flow velocity field model;
adjusting the starting values to generate modified values based on at least one operating parameters of the ultrasound system;
comparing the modified values to measured values derived from the echo signals acquired in the vicinity of the first or second orifice location;
generating an error term based on the comparing;
adjusting the flow velocity field model based on the comparing; and
iteratively repeating the processing of the echo signals until the error term is reduced to a value indicating that the modified values and the measured values converge; and
combining vectorially the vector velocity fields of regurgitant flow through the first and second orifice locations.
2. The method of claim 1 , wherein the first processing step further comprises Doppler processing the echo signals to identify flow vectors toward the first orifice location; and wherein the second processing step further comprises Doppler processing the echo signals to identify flow vectors toward the second orifice location.
3. The method of claim 1 , wherein the first acquiring step further comprises acquiring ultrasound echo signals from a two dimensional acceptance zone proximal the first orifice location; and wherein the second acquiring step further comprises acquiring ultrasound echo signals from a two dimensional acceptance zone proximal the second orifice location.
4. The method of claim 3 , wherein each acceptance zone is arcuate in shape having a center of curvature substantially at the first or second orifice location.
5. The method of claim 3 , wherein the two acceptance zones are spatially overlapping.
6. The method of claim 1 , wherein the first acquiring step further comprises acquiring ultrasound echo signals from a three dimensional acceptance zone proximal the first orifice location; and wherein the second acquiring step further comprises acquiring ultrasound echo signals from a three dimensional acceptance zone proximal the second orifice location.
7. The method of claim 6 , wherein each acceptance zone is hemispherical in shape having a center of curvature substantially at the first or second orifice location.
8. The method of claim 6 , wherein the two acceptance zones are spatially overlapping.
9. The method of claim 1 , wherein the first and second orifice locations each comprise the location of a pinhole leak of a closed mitral valve.
10. The method of claim 1 , wherein the first and second orifice locations each comprise a location on a slit leak of a closed mitral valve.
11. The method of claim 1 , wherein combining vectorially further comprises summing a plurality of vector velocity fields for a plurality of orifices and displaying a quantification of total flow rate or volume flow for multiple or slit orifices.
12. The method of claim 1 , wherein the operating parameters of the ultrasound system includes one or more of Doppler angle, wall filter bias, spectral spread, or aliasing effects.