ASSESSMENT OF RIGHT VENTRICULAR FUNCTION USING CONTRAST ECHOCARDIOGRAPHY

• US 20150005629A1
• Filed: 06/26/2014
• Published: 01/01/2015
• Est. Priority Date: 06/26/2013
• Status: Active Grant

• Current Assignee: Vanderbilt University
• Original Assignee: Vanderbilt University
• Inventors: Boronyak, Steven M., Merryman, William David, Monahan, Kenneth J., Brittain, Evan
• Granted Patent: US 9,883,850 B2
• Time in Patent Office: Days
• US Class Current: 600/431
• CPC Class Codes: A61B 8/0883 for diagnosis of the heart
• CPC Class Codes: A61B 8/481 involving the use of contrast agent, e.g. microbubbles introduced into the bloodstream analysis of echo signal exploiting properties of a contrast enhancer in devices for short-range imaging with acoustic waves G01S7/52039
• CPC Class Codes: A61B 8/5223 for extracting a diagnostic or physiological parameter from medical diagnostic data for algorithms to analyse biomedical images G06T7/0012
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/10132 Ultrasound image
• CPC Class Codes: G06T 2207/30048 Heart; Cardiac
• CPC Class Codes: G06T 2207/30104 Vascular flow; Blood flow; Perfusion
• CPC Class Codes: G06T 7/0016 involving temporal comparison
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

Systems and methods are provided for determining a right ventricular transit time for a patient. An echodense contrast is injected into a patient. A first representative region, representing the right ventricle of the patient, is selected. A second representative region, representing the bifurcation of the main pulmonary artery, is selected. Respective first and second time series of intensity values for the first and second representative regions are generated via echocardiography. The right ventricular transit time is determined from the first and second time series of intensity values. The right ventricular transit time is displayed to a user.

Claims

1. A method for determining a right ventricular transit time for a patient comprising:

injecting an echodense contrast agent into a patient;

selecting a first representative region representing a right ventricle of the patient;

selecting a second representative region representing a bifurcation of the main pulmonary artery;

generating respective first and second time series of intensity values for the first and second representative regions via echocardiography;

determining the right ventricular transit time from the first and second time series of intensity values; and

displaying the right ventricular transit time to a user.

2. The method of claim 1, wherein determining the right ventricular transit time from the first and second time series of intensity values comprises determining a time interval between a peak intensity in the first time series of intensity values and a corresponding peak intensity in the second time series of intensity values.

3. The method of claim 1, wherein determining the right ventricular transit time from the first and second time series of intensity values comprises determining a time interval between a first time at which the first time series of intensity values exceeds a first threshold intensity value and a first time at which the second time series of intensity values exceeds a second threshold intensity value.

4. The method of claim 1, wherein determining the right ventricular transit time from the first and second time series of intensity values comprises:

determining a first time associated with a first inflection point, representing a rise in signal intensity, from a first time series of intensity values;

determining a second time, associated with a second inflection point, representing a rise in signal intensity, from a second time series of intensity values; and

determining a time interval between the first time and the second time.

5. The method of claim 4, wherein determining the first time associated with the first inflection point comprises:

identifying a portion of the first time series of intensity values representing a rise of signal intensity above a determined baseline;

fitting a model to the identified portion of the first time series of intensity values to provide a time-dependent function; and

determining the inflection point at a point at a local maximum of the derivative of the time-dependent function.

6. The method of claim 5, wherein fitting the model to the identified portion of the first time series of intensity values comprises fitting a local-density random walk model to the identified portion of the first time series of intensity values.

7. The method of claim 5, wherein fitting the model to the identified portion of the first time series of intensity values comprises fitting a sigmoidal model to the identified portion of the first time series of intensity values.

8. The method of claim 4, wherein determining the first time associated with the first inflection point comprises:

calculating a derivative of the first time series of intensity values;

windowing the calculated derivative to a region of interest;

identify all local maxima in the region of interest; and

selecting the first time associated with the first inflection point from times associated with the identified local maxima.

9. The method of claim 1, selecting the first representative region representing the right ventricle of the patient comprises selecting a region between one and two millimeters from the coaptation point of the tricuspid valve and centered between the right ventricular free wall and the interventricular septum.

10. The method of claim 1, further comprising:

selecting a third representative region representing a left atrium of the patient;

generating a third time series of intensity values for the third representative region via echocardiography; and

determining a pulmonary transit time from the first and third time series of intensity values.

11. The method of claim 10, further comprising calculating a ratio of the right ventricular transit time to the pulmonary transit time.

12. The method of claim 1, further comprising providing the right ventricular transit time as a feature to a statistical model configured to evaluate a function of the right ventricle of the patient.

13. A method for determining a transit time for a patient comprising:

injecting an echodense contrast agent into a patient;

selecting a first representative region and a second representative region;

generating respective first and second time series of intensity values for the first and second representative regions via echocardiography;

locating at least one inflection point in each of the first and second time series of intensity values;

determining the transit time from the at least one inflection point located in each of the first and second time series of intensity values; and

displaying the transit time to a user.

14. The method of claim 13, wherein locating the at least one inflection point in each of the first and second time series of intensity values comprises:

identifying a portion of the each time series of intensity values representing a rise of signal intensity above a determined baseline;

fitting a model to each identified portion to provide respective first and second time-dependent functions;

determining an inflection point of the at least one inflection point for the first time series of intensity values at a point at a local maximum of the derivative of the first time-dependent function; and

determining an inflection point of the at least one inflection point for the second time series of intensity values at a point at a local maximum of the derivative of the second time-dependent function.

15. The method of claim 14, wherein fitting the model to each identified portion comprises fitting a local-density random walk model to the identified portion.

16. The method of claim 14, wherein fitting the model to each identified portion comprises fitting a sigmoidal model to the identified portion.

17. The method of claim 13, wherein locating the at least one inflection point in each of the first and second time series of intensity values comprises:

calculating a derivative of each of the first and second time series of intensity values;

windowing each calculated derivative to respective first and second regions of interest; and

identify all local maxima in each region of interest.

18. The method of claim 17, wherein determining the transit time from the at least one inflection point located in each of the first and second time series of intensity values comprises:

selecting a first inflection point, representing an initial rise in signal intensity, from the identified local maxima of the first region of interest;

selecting a second inflection point, representing an initial rise in signal intensity, from the identified local maxima of the second region of interest; and

determining the transit time as a time interval between a first time, associated with the first inflection point, and a second time.

19. A system for non-invasive evaluation of right ventricular function using contrast-enhanced echocardiography, comprising:

an ultrasound assembly configured to image a region containing at least a right ventricle and a bifurcation of the main pulmonary artery to provide a first time series of intensity values representing the right ventricle and a second time series of intensity values representing the first branch of the main pulmonary artery;

a parameter calculation component configured to determine at least a right ventricular transit time (RVTT) from the first and second time series of intensity values;

a modeling component configured to provide a parameter representing the right ventricular function of the patient from at least the determined RVTT; and

an output device configured to provide the parameter provided by the modeling component to a user in a human comprehensible form.

20. The system of claim 19, wherein the parameter calculation component is configured to determine the right ventricular transit time from the first and second time series of intensity values comprises determining a time interval between a peak intensity in the first time series of intensity values and a corresponding peak intensity in the second time series of intensity values.

21. The system of claim 19, wherein the parameter calculation component is configured to determine the right ventricular transit time from the first and second time series of intensity values comprises determining a time interval between a first time at which the first time series of intensity values exceeds a first threshold intensity value and a first time at which the second time series of intensity values exceeds a second threshold intensity value.

22. The system of claim 19, wherein the parameter calculation component is configured to determine the right ventricular transit time from the first and second time series of intensity values comprises:

determining a first time associated with a first inflection point, representing a rise in signal intensity, from a first time series of intensity values;

determining a second time, associated with a second inflection point, representing a rise in signal intensity, from a second time series of intensity values; and

determining a time interval between the first time and the second time.

23. A method for determining a transit time for a patient comprising:

injecting an echodense contrast agent into a patient;

selecting a first representative region and a second representative region;

generating respective first and second time series of intensity values for the first and second representative regions via echocardiography;

locating a point of largest change in each of the first and second time series of intensity values, the point of largest change representing a time, m, that minimizes the following function of m;