Systems and methods for determining plaque vulnerability to rupture

• US 20070232883A1
• Filed: 01/30/2007
• Published: 10/04/2007
• Est. Priority Date: 02/15/2006
• Status: Abandoned Application

• Current Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Original Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Inventors: Ilegbusi, Olusegun
• Application Number:
  US11/699,935
• Publication Number:
  US 20070232883A1
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: A61B 1/00082 Balloons
• CPC Class Codes: A61B 1/00096 Optical elements
• CPC Class Codes: A61B 1/00177 for 90 degrees side-viewing
• CPC Class Codes: A61B 1/005 Flexible endoscopes
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/0086 using infrared radiation
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/061 Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body A61B1/00158 takes precedence
• CPC Class Codes: A61B 5/6852 Catheters
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: A61B 6/5247 combining images from an ionising-radiation diagnostic technique and a non-ionising radiation diagnostic technique, e.g. X-ray and ultrasound
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: A61B 8/4416 related to combined acquisition of different diagnostic modalities, e.g. combination of ultrasound and X-ray acquisitions
• CPC Class Codes: A61B 8/543 involving acquisition triggered by a physiological signal

Abstract

In some embodiments, stress values for a diseased artery are obtained, stress ratios are determined from the obtained stress values, and a flow-structure interaction index is generated based upon the stress ratios as a function of a given plaque characteristic. In further embodiments, a plaque characteristic of a patient is determined, a patient'"'"'s stress ratio is determined in relation to the flow-structure interaction index and the plaque characteristic, and the patient'"'"'s stress ratio is compared to a critical stress ratio to determine whether the patient'"'"'s stress ratio exceeds the critical stress ratio.

Claims

1. A method for determining plaque rupture potential , the method comprising:

obtaining stress values for a diseased artery;

determining stress ratios from the obtained stress values; and

generating a flow-structure interaction index based upon the stress ratios as a function of a given plaque characteristic.

2. The method of claim 1, wherein obtaining stress values comprises obtaining stress values through mathematical modeling and mathematical computation of the stress values.

3. The method of claim 1, wherein obtaining stress values comprises obtaining stress values through subject testing and determination of the stress values.

4. The method of claim 1, wherein obtaining stress values comprises obtaining stress values through physical modeling and measurement of the stress values.

5. The method of claim 1, wherein obtaining stress values comprises obtaining flow-related stress values and structure-related stress values.

6. The method of claim 5, wherein obtaining flow-related stress values comprises obtaining shear stress values at a plaque-blood interface and wherein obtaining structure-related stress values comprises obtaining structural stress values within a fibrous cap of a plaque.

7. The method of claim 6, wherein the structural stress values comprises one of maximum principal stress values or Von Mises stress values.

8. The method of claim 1, wherein determining stress ratios comprises determining ratios between flow-related stress values and structure-related stress values.

9. The method of claim 8, wherein determining ratios between flow-related stress values and structure-related stress values comprises determining ratios between shear stress values at a plaque-blood interface and structural stress values within a fibrous cap of a plaque.

10. The method of claim 1, wherein generating a flow-structure interaction index comprises calculating the stress ratios as a function of stenosis level.

11. The method of claim 1, wherein generating a flow-structure interaction index comprises calculating the stress ratios as a function of fibrous cap thickness.

12. The method of claim 1, wherein generating a flow-structure interaction index comprises calculating the stress ratios as a function of lipid pool position.

13. The method of claim 1, wherein generating a flow-structure interaction index comprises calculating the stress ratios as a function of a ratio of lipid pool volume versus total plaque volume.

14. The method of claim 1, wherein generating a flow-structure interaction index comprises generating multiple flow-structure interaction indices for various levels of blood pressure.

15. The method of claim 1, further comprising determining a plaque characteristic of a patient and determining a patient stress ratio.

16. The method of claim 15, further comprising comparing the patient stress ratio with a critical stress ratio and, if the patient stress ratio exceeds the critical stress ratio, determining that a plaque of the patient is vulnerable to rupture.

17. A method for generating a flow-structure interaction index, the method comprising:

determining shear stresses that act upon an arterial plaque due to blood flow;

determining structural stresses within a fibrous cap of the arterial plaque resulting from internal resistance within the fibrous cap due to pressure imposed by the blood flow;

calculating stress ratios that comprise ratios of the shear stresses and the structural stresses; and

calculating a flow-structure interaction index that comprises a relation of stress ratio as a function of a given plaque characteristic.

18. The method of claim 17, wherein calculating a flow-structure interaction index comprises calculating stress ratio as a function of one of stenosis level, fibrous cap thickness, lipid pool position, or a ratio of lipid pool volume versus total plaque volume.

19. The method of claim 17, wherein calculating a flow-structure interaction index comprises generating multiple flow-structure interaction indices for various levels of blood pressure.

20. A method of determining plaque rupture potential, the method comprising:

determining a plaque characteristic of a patient under evaluation;

using the plaque characteristic to determine a patient stress ratio through reference to a flow-structure interaction index that comprises a relation of stress ratio as a function of the plaque characteristic, the stress ratio comprising a ratio of shear stress and structural stress;

comparing the patient stress ratio to a critical stress ratio over which a plaque is vulnerable to rupture; and

determining whether the plaque is vulnerable to rupture relative to the comparison.

21. The method of claim 20, wherein the plaque characteristic comprises of one of stenosis level, fibrous cap thickness, lipid pool position, or a ratio of lipid pool volume versus total plaque volume.

22. The method of claim 20, wherein the flow-structure interaction index has been calculated relative to a given blood pressure level.

23. A computer-readable medium comprising:

logic configured to determine shear stresses that act upon an arterial plaque due to blood flow;

logic configured to determine structural stresses within a fibrous cap of the arterial plaque resulting from internal resistance within the fibrous cap due to pressure imposed by the blood flow;

logic configured to calculate stress ratios that comprise ratios of the shear stresses and the structural stresses; and

logic configured to calculate a flow-structure interaction index that comprises a relation of stress ratio as a function of a given plaque characteristic.

24. The method of claim 23, wherein the logic configured to calculate a flow-structure interaction index comprises logic configured to calculate stress ratio as a function of one of stenosis level, fibrous cap thickness, lipid pool position, or a ratio of lipid pool volume versus total plaque volume.

25. The method of claim 23, wherein the logic configured to calculate a flow-structure interaction index comprises logic configured to generate multiple flow-structure interaction indices for various levels of blood pressure.

26. A plaque vulnerability determination system, the system comprising:

means for determining a plaque characteristic of a patient under evaluation; and

means for determining a patient stress ratio, the stress ratio comprising a ratio of shear stress and structural stress that act upon and in a plaque of the patient.

27. The system of claim 26, wherein the plaque characteristic comprises of one of stenosis level, fibrous cap thickness, lipid pool position, or a ratio of lipid pool volume versus total plaque volume.

28. The system of claim 26, wherein the means for determining a patient stress ratio comprise a flow-structure interaction index that comprises a relation of stress ratio as a function of the plaque characteristic.

29. The system of claim 26, further comprising means for comparing the patient stress ratio to a critical stress ratio over which a plaque is vulnerable to rupture.

30. The system of claim 29, further comprising means for determining whether the plaque is vulnerable to rupture relative to the comparison.