Methods for determining intracranial pressure non-invasively

• US 7,547,283 B2
• Filed: 06/03/2004
• Issued: 06/16/2009
• Est. Priority Date: 11/28/2000
• Status: Expired due to Fees

• Current Assignee: PhysioSonics, Inc., Washington University In St Louis
• Original Assignee: PhysioSonics, Inc.
• Inventors: Mohr, Brandt, Frederickson, Robert C. A., Mourad, Pierre D., Kliot, Michel
• Primary Examiner(s): Casler; Brian L.
• Assistant Examiner(s): Shahrestani; Nasir
• Application Number:
  US10/861,197
• Publication Number:
  US 20050015009A1
• Time in Patent Office: 1,839 Days
• Field of Search: 600407-480
• US Class Current: 600/459
• CPC Class Codes: A61B 5/0051 by applying vibrations
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: A61B 5/4064 Evaluating the brain A61B5/031, A61B5/369, A61B5/14553 take precedence
• CPC Class Codes: A61B 5/415 the glands, e.g. tonsils, adenoids or thymus
• CPC Class Codes: A61B 5/418 lymph vessels, ducts or nodes
• CPC Class Codes: A61B 5/4824 Touch or pain perception evaluation A61B5/4821 takes precedence
• CPC Class Codes: A61B 5/7267 involving training the classification device
• CPC Class Codes: A61B 8/00 Diagnosis using ultrasonic, sonic or infrasonic waves imaging of objects using sonar G01S15/00
• CPC Class Codes: A61B 8/04 Measuring blood pressure
• CPC Class Codes: A61B 8/065 to determine blood output from the heart in general A61B5/029
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence
• CPC Class Codes: A61B 8/0808 for diagnosis of the brain
• CPC Class Codes: A61B 8/4236 characterised by adhesive patches
• CPC Class Codes: A61B 8/4444 related to the probe
• CPC Class Codes: A61B 8/4472 Wireless probes
• CPC Class Codes: A61B 8/4483 characterised by features of the ultrasound transducer
• CPC Class Codes: A61B 8/485 involving measuring strain or elastic properties
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: G16H 50/70 for mining of medical data, e.g. analysing previous cases of other patients

Abstract

Systems and methods for determining ICP based on parameters that can be measured using non-invasive or minimally invasive techniques are provided, wherein a non-linear relationship is used to determine ICP based on one or more variable inputs. The first variable input relates to one or more properties of a cranial blood vessel and/or blood flow, such as acoustic backscatter from an acoustic transducer having a focus trained on a cranial blood vessel, flow velocity in a cranial blood vessel, and the like. Additional variables, such as arterial blood pressure (ABP), may be used in combination with a first variable input relating to one or more properties of a cranial blood vessel, such as flow velocity of the middle cerebral artery (MCA) to derive ICP using a non-linear relationship. Methods and systems for locating target areas based on their acoustic properties and for acoustic scanning of an area, identification of a target area of interest based on acoustic properties, and automated focusing of an acoustic source and/or detector on a desired target area are also provided. Acoustic transducer assemblies are described.

Claims

1. A method for determining ICP of a subject based on at least two variable inputs, comprising:

acquiring acoustic data from a target site on a cranial blood vessel of the subject and using, as a first variable input, the acoustic data or a measurement derived from the acoustic data;

acquiring, as a second variable input, arterial blood pressure (ABP) data; and

determining ICP based on the first and second variable inputs using a non-linear relationship.

2. A method of claim 1, wherein the acoustic data is selected from the group consisting of:

acoustic scatter and changes in acoustic scatter, including values of and changes in amplitude, phase and/or frequency of acoustic signals, values of and changes in length of scattered signals relative to the interrogation signal, values of and changes in the primary and/or other maxima and/or minima amplitudes of an acoustic signal within a cardiac and/or respiratory cycle;

ratios of and changes in the ratios of the maximum and/or minimum amplitude to that of mean or variance or distribution of subsequent signals within a cardiac cycle, values of and changes in temporal or spatial variance of scattered or emitted signals at different times in the same target location and/or at the same time in different target locations, values of and rates of change of endogenous and/or induced brain tissue displacement or relaxation, acoustic emissions produced by the endogenous and/or induced brain tissue displacement or relaxation, and combinations thereof.

3. A method of claim 1, wherein the first variable input is acoustic scatter data.

4. A method of claim 1, wherein the first variable input is blood flow velocity in a cranial blood vessel.

5. A method of claim 1, wherein the first variable input is acquired using transcranial Doppler (TCD) techniques.

6. A method of claim 1, wherein ABP is measured non-invasively.

7. A method of claim 1, wherein ABP is measured using active and/or passive ultrasound techniques.

8. A method of claim 1, wherein ABP is measured using an active and/or passive ultrasound technique at a target site on a cranial blood vessel.

9. A method of claim 1, wherein the acoustic data is acquired from a first target site on a cranial blood vessel and data for determining ABP is acquired from a second CNS target site different from the first target site.

12. A method of claim 1, wherein the acoustic data and ABP data are acquired by and processed in an integrated electronic device and are synchronous.

13. A method of claim 1, wherein the acoustic data and ABP data acquired are not synchronous, additionally comprising synchronizing the acoustic scatter and ABP data prior to determining ICP.

14. A method of claim 1, additionally comprising aligning the input variable data with respect to cardiac cycle boundaries prior to determining ICP.

15. A method of claim 1, wherein the ICP is derived using a non-linear, empirically derived relationship.

16. A method of claim 1, wherein the non-linear relationship of acoustic data and ABP data to ICP is derived using a neural network technique.

17. A method of claim 1, wherein the non-linear relationship of acoustic data and ABP data to ICP is derived using a first principles relationship.

18. A method of claim 1, wherein the non-linear relationship of acoustic data and ABP data to ICP is derived using a combined empirical/first principles approach, and the first principles approach is based on linear or non-linear relationships.

19. A method of claim 1, additionally comprising displaying at least one of acoustic data or a measurement derived from acoustic data and an image representing the target site.

20. A method of claim 1, additionally comprising scanning a CNS target area using at least one acoustic source/receiver array composed of multiple acoustic source and receiver elements;

localizing a desired CNS target site within the CNS target area based on acoustic data acquired during scanning; and

focusing one or more source and receiver elements on the desired CNS target site prior to collecting acoustic data.

21. A method of claim 1, wherein acoustic data is acquired using an acoustic transducer array.

22. A method of claim 1, wherein the ABP data is acquired from a target site on a cranial blood vessel of the subject.

23. A method of claim 22, wherein the target site for acquisition of the acoustic data and the target site for acquisition of the ABP data are on the same cranial blood vessel.

24. A method of claim 22, wherein the target site for acquisition of the acoustic data and the target site for acquisition of the ABP data is the middle cerebral artery (MCA).

25. A method of claim 1, wherein the target site for acquisition of the acoustic data and a target site for acquisition of the ABP data are different.

26. A method of claim 1, wherein there is a likelihood that 95% of the ICP values determined using the method are within 1.68 mmHg of an invasively measured ICP value.

27. A method of claim 1, wherein for seven of eight subjects for whom ICP determinations are made, the average value of instantaneous differences between ICP determined using the non-linear relationship between the first and second variables and ICP measured invasively is less than 2 mmHg.

28. A method of claim 1, wherein for 75% of subjects for whom ICP determinations are made, the average value of instantaneous differences between ICP determined using the non-linear relationship between the first and second variables and ICP measured invasively is less than 1 mmHg.

10. A method for determining ICP of a subject based on at least three variable inputs, comprising:

acquiring acoustic data from a target site on or in a cranial blood vessel of the subject and using, as a first variable input, the acoustic data or a measurement derived from the acoustic data;

acquiring, as a second variable input, arterial blood pressure (ABP) data;

acquiring, as a third variable input, physiological data relating to a physiological property other than blood flow velocity and ABP; and

determining ICP based on the first, second and third variable inputs using a non-linear relationship.

11. A method of claim 10, wherein the third variable input is selected from the group consisting of:

CNS tissue stiffness, brain tissue displacement, partial pressure of at least one or more gases associated with brain respiration and metabolism, pCO₂, blood perfusion, hematocrit, EKG and electrophysiological properties.

29. A method for determining intracranial pressure (ICP) of a subject based on at least two variable inputs, each variable input being acquired using non-invasive techniques, comprising:

acquiring acoustic data from a first target site on a cranial blood vessel of the subject and using, as a first variable input, the acoustic data or a measurement derived from the acoustic data;

acquiring a second variable input relating to one or more acoustic properties of a target CNS site, the second variable input being different from the first variable input and being selected from the group consisting of;

acoustic scatter and changes in acoustic scatter, including values of and changes in amplitude, phase and/or frequency of acoustic signals, values of and changes in length of scattered signals relative to the interrogation signal, values of and changes in the primary and/or other maxima and/or minima amplitudes of an acoustic signal within a cardiac and/or respiratory cycle;

ratios of and changes in the ratios of the maximum and/or minimum amplitude to that of mean or variance or distribution of subsequent signals within a cardiac cycle, values of and changes in temporal or spatial variance of scattered or emitted signals at different times in the same target location and/or at the same time in different target locations, values of and rates of change of endogenous and/or induced tissue displacement or relaxation, acoustic emissions produced by the endogenous and/or induced tissue displacement or relaxation, and combinations thereof; and

determining ICP based on the first and second variable inputs using a non-linear relationship.

30. A method of claim 29, wherein the target CNS site is different from the first target site on a cranial blood vessel.

31. A method of claim 29, wherein the first target site on a cranial blood vessel is the MCA or a carotid or a vertebral artery.

32. A method of claim 29, wherein the first variable input is acoustic scatter data.

33. A method of claim 32, wherein the second variable input is ABP.

34. A method of claim 33, wherein the ABP measured using active and/or passive acoustic techniques.

35. A method of claim 29, wherein the first variable input is acoustic scatter and the second variable input is CNS tissue displacement.

36. A method of claim 35, wherein the CNS tissue displacement is measured using active and/or passive acoustic techniques.

37. A method of claim 29, wherein the first variable input is acoustic scatter data acquired from a target site on a cranial blood vessel and the second variable input is acoustic scatter data acquired from one or more target CNS sites different from the target site on the cranial blood vessel.

38. A method of claim 29, wherein the first variable input is acoustic scatter, the second variable input is CNS tissue displacement, and additionally comprising acquiring ABP as a third variable input and determining ICP based on the first, second and third variable inputs.

39. A method for determining intracranial pressure (ICP) of a subject based on at least two variable inputs, comprising:

locating and acoustically illuminating a desired target site in an automated fashion using an array comprising a plurality of acoustic source and/or detector elements by operating the array to acquire acoustic data from numerous sites within a larger target area, selecting at least one localized target site within the target area based on the acoustic data acquired for focused acoustic illumination and/or probing, and focusing the acoustic source and/or detector elements on the at least one selected localized target site and acquiring acoustic data from the at least one selected localized target site;

using the acquired acoustic data from the at least one selected localized target site as a variable input;

acquiring another variable input from acquired acoustic data or from an arterial blood pressure (ABP) measurement; and

determining ICP based on the variable inputs using a non-linear relationship.

40. A method of claim 39, wherein selection of a localized target site is predetermined based on an acoustic property selected from the group consisting of:

acoustic scatter data;

Doppler analysis of acoustic scatter data, phase or frequency of acoustic scatter data;

changes in the primary and/or other maxima and/or minima amplitude, phase or frequency of acoustic signals within a cardiac and/or respiratory cycle.

41. A method of claim 39, wherein selection of a localized target site is predetermined based on a determination derived from acoustic data selected from the group consisting of:

flow velocity, tissue stiffness properties, endogenous and/or induced tissue displacement properties, acoustic emissions associated with tissue displacements, and rates of change of such properties.

42. A method of claim 39, wherein selection of the localized target site is determined based on the localized site of highest amplitude acoustic scatter.

43. A method of claim 39, wherein the selected localized target site is on the MCA.