System and method for image based physiological monitoring of cardiovascular function

• US 20070135705A1
• Filed: 12/07/2006
• Published: 06/14/2007
• Est. Priority Date: 12/08/2005
• Status: Active Grant

• Current Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Inventors: Maier, Corinna, Lorenz, Christine
• Granted Patent: US 8,577,441 B2
• Time in Patent Office: Days
• US Class Current: 600/410
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: G06T 2207/10088 Magnetic resonance imaging [MRI]
• CPC Class Codes: G06T 2207/30048 Heart; Cardiac
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: G06T 7/149 involving deformable models, e.g. active contour models
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51

Abstract

A method for real time monitoring of cardiac function includes defining a plurality of planes through a heart from which to acquire heart imaging data, acquiring a sequence of 2-dimensional images from said selected planes, wherein each said image comprises a plurality of intensities defined on a domain of points on a 2D grid, selecting one or more of said sequence of images to provide imaging data for monitoring heart function, wherein said remaining unselected images are adapted for diagnostic purposes, and repeating said steps of acquiring a sequence of 2-dimensional images from said selected planes and selecting one or more of said sequence of images for monitoring heart function, wherein a time sequence of images is obtained, alternating between images for monitoring heart function and images for diagnostic purposes.

Claims

1. A method for real time monitoring of cardiac function comprising the steps of:

selecting a plane through a heart from which to acquire heart function data;

acquiring a 2-dimensional image from said selected plane, wherein said image comprises a plurality of intensities defined on a domain of points on a 2D grid;

selecting a center of a chamber of said heart;

projecting a plurality of beams into said image through said chamber center, each beam comprising a substantially collinear subset of points in said image;

sampling image intensities along each point of said beam; and

repeating said steps of acquiring a 2-dimensional image, projecting a plurality of virtual beams into said image, and calculating an image intensity to obtain a series of time measurements wherein an image intensity along each said beam can be plotted as a function of time.

2. The method of claim 1, further comprising bilinearly interpolating additional intensities between sampled points along each said beam.

3. The method of claim 1, further comprising detecting endocardial contours from said plurality of beams.

4. The method of claim 3, wherein said endocardial contour is detected using a horizontal 1D Canny filter.

5. The method of claim 3, wherein said endocardial contour is detected using an active contour model that minimizes an energy that is a weighted sum of external constraint forces determined by said image and internal constraint forces that depend on the shape of the contour.

6. The method of claim 3, further comprising calculating distances between said detected endocardial contours, wherein the maximum distances as a function of time in each projection beam are taken as the end-diastolic (ED) diameter, and the minimum distances are taken as the end-systolic (ES) diameter.

7. The method of claim 6, further comprising calculating a chamber area from the area enclosed by the points of the endocardial contour, and calculating an ejection fraction from EDV-ESV/EDV, wherein EDV is the end-diastolic chamber area and ESV is the end-systolic chamber area.

8. The method of claim 7, wherein said chamber is the left ventricle.

9. The method of claim 3, further comprising detecting epicardial contours from said plurality of beams, and calculating a wall thickness as a function of time from said endocardial contours and said epicardial contours.

10. The method of claim 1, further comprising using said image intensity time plots along each said beam to detect changes in values of a physiological parameter over time, wherein detecting value changes comprises selecting a clinically relevant change threshold, maintaining a running average of said parameter values over a predetermined number of previous heartbeats, and comparing a parameter value at each heartbeat to either the running average value or a baseline value for said parameter.

11. The method of claim 1, wherein said acquired image is part of a sequence of images that include images acquired for diagnostic purposes.

12. A method for real time monitoring of cardiac function comprising the steps of:

defining a plurality of planes through a heart from which to acquire heart imaging data;

acquiring a sequence of 2-dimensional images from said selected planes, wherein each said image comprises a plurality of intensities defined on a domain of points on a 2D grid;

selecting one or more of said sequence of images to provide imaging data for monitoring heart function, wherein said remaining unselected images are adapted for diagnostic purposes; and

repeating said steps of acquiring a sequence of 2-dimensional images from said selected planes and selecting one or more of said sequence of images for monitoring heart function, wherein a time sequence of images is obtained, alternating between images for monitoring heart function and images for diagnostic purposes.

13. The method of claim 12, further comprising, for each monitoring image, selecting a center of a chamber of said heart, projecting a plurality of beams into said image through said chamber center, each beam comprising a substantially collinear subset of points in said image, and sampling image intensities along each point of said beam, to obtain a series of time measurements wherein an image intensity along each said beam can be plotted as a function of time.

14. The method of claim 12, wherein every n^th image is selected for monitoring heart function.

15. The method of claim 13, further comprising, analyzing said image-intensity time behavior over a pre-determined time period after intravenous administration of a contrast agent.

16. The method of claim 12, wherein said images are magnetic resonance (MR) phase images, and further comprising plotting the MR phase encoded for velocity as a function of time, and deriving performance parameters from said phase-time plot, including one or more of time to peak flow, percentage regurgitant flow, and peak flow velocity.

17. The method of claim 16, where each said phase image is a 1D image created by using a pencil beam 2D radio-frequency excitation to derive measurements from a column of tissue.

18. The method of claim 16, where each said phase image is a 2D image created from a velocity encoded MR image.

19. A program storage device readable by a computer, tangibly embodying a program of instructions executable by the computer to perform the method steps for real time monitoring of cardiac function, said method comprising the steps of:

selecting a plane through a heart from which to acquire heart function data;

acquiring a 2-dimensional image from said selected plane, wherein said image comprises a plurality of intensities defined on a domain of points on a 2D grid;

selecting a center of a chamber of said heart;

projecting a plurality of beams into said image through said chamber center, each beam comprising a substantially collinear subset of points in said image;

sampling image intensities along each point of said beam; and

repeating said steps of acquiring a 2-dimensional image, projecting a plurality of virtual beams into said image, and calculating an image intensity to obtain a series of time measurements wherein an image intensity along each said beam can be plotted as a function of time.

20. The computer readable program storage device of claim 19, the method further comprising bilinearly interpolating additional intensities between sampled points along each said beam.

21. The computer readable program storage device of claim 19, the method further comprising detecting endocardial contours from said plurality of beams.

22. The computer readable program storage device of claim 21, wherein said endocardial contour is detected using a horizontal 1D Canny filter.

23. The computer readable program storage device of claim 21, wherein said endocardial contour is detected using an active contour model that minimizes an energy that is a weighted sum of external constraint forces determined by said image and internal constraint forces that depend on the shape of the contour.

24. The computer readable program storage device of claim 21, the method further comprising calculating distances between said detected endocardial contours, wherein the maximum distances as a function of time in each projection beam are taken as the end-diastolic (ED) diameter, and the minimum distances are taken as the end-systolic (ES) diameter.

25. The computer readable program storage device of claim 24, the method further comprising calculating a chamber area from the area enclosed by the points of the endocardial contour, and calculating an ejection fraction from EDV-ESV/EDV, wherein EDV is the end-diastolic chamber area and ESV is the end-systolic chamber area.

26. The computer readable program storage device of claim 25, wherein said chamber is the left ventricle.

27. The computer readable program storage device of claim 21, the method further comprising detecting epicardial contours from said plurality of beams, and calculating a wall thickness as a function of time from said endocardial contours and said epicardial contours.

28. The computer readable program storage device of claim 19, the method further comprising using said image intensity time plots along each said beam to detect changes in values of a physiological parameter over time, wherein detecting value changes comprises selecting a clinically relevant change threshold, maintaining a running average of said parameter values over a predetermined number of previous heartbeats, and comparing a parameter value at each heartbeat to either the running average value or a baseline value for said parameter.

29. The computer readable program storage device of claim 19, wherein said acquired image is part of a sequence of images that include images acquired for diagnostic purposes.

30. The computer readable program storage device of claim 19, the method further comprising analyzing said image-intensity time behavior over a pre-determined time period after intravenous administration of a contrast agent.

31. The computer readable program storage device of claim 19, wherein said images are magnetic resonance (MR) phase images, and the method further comprising plotting the MR phase encoded for velocity as a function of time, and deriving performance parameters from said phase-time plot, including one or more of time to peak flow, percentage regurgitant flow, and peak flow velocity.

32. The computer readable program storage device of claim 31, where each said phase image is a 1D image created by using a pencil beam 2D radio-frequency excitation to derive measurements from a column of tissue.

33. The computer readable program storage device of claim 31, where each said phase image is a 2D image created from a velocity encoded MR image.