Systems and methods for making noninvasive physiological assessments

• US 20020095087A1
• Filed: 11/28/2001
• Published: 07/18/2002
• Est. Priority Date: 11/28/2000
• Status: Active Grant

• Current Assignee: PhysioSonics, Inc.
• Original Assignee: Allez Physionix Ltd.
• Inventors: Mourad, Pierre D., Kliot, Michel, Patterson, Rex, Jarvik, Jeffrey G., Mesiwala, Ali
• Granted Patent: US 6,875,176 B2
• Time in Patent Office: Days
• US Class Current: 600/442
• CPC Class Codes: A61B 5/0048 Detecting, measuring or recording by applying mechanical forces or stimuli A61B5/021, A61B5/4884 and A61B9/00 take precedence
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: A61B 5/4058 for evaluating the central nervous system A61B5/4806, A61B5/4821 take precedence
• 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 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 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence
• CPC Class Codes: A61B 8/0816 using echo-encephalography
• CPC Class Codes: A61B 8/485 involving measuring strain or elastic properties
• CPC Class Codes: A61B 8/488 involving Doppler signals

Abstract

Systems and methods for assessment of tissue properties, noninvasively, by acquiring data relating to at least one aspect of intrinsic and/or induced tissue displacement, or associated biological responses, are provided. Data relating to tissue displacement and associated biological changes may be acquired by detecting acoustic properties of tissue using ultrasound interrogation pulses, preferably in a scatter or Doppler detection mode. Based on this data, tissue properties are assessed, characterized and monitored. Specific applications for systems and methods of the present invention include non-invasive assessment and monitoring of intracranial pressure (ICP), arterial blood pressure (ABP), CNS autoregulation status, vasospasm, stroke, local edema, infection and vasculitus, as well as diagnosis and monitoring of diseases and conditions that are characterized by physical changes in tissue properties. Methods and systems for localizing physiological condition(s) and/or biological response(s), such as pain, by targeting and selectively probing tissues using the application of focused ultrasound are also provided.

Claims

1. A method for detecting a physiological property of a target tissue, comprising:

noninvasively inducing a tissue displacement at a target tissue site by applying an ultrasound pulse;

noninvasively acquiring data relating to the induced tissue displacement at or in proximity to the target tissue site; and

relating the acquired data relating to the induced tissue displacement with a physiological property of the target tissue.

2. A method of claim 1, wherein the data acquired relating to the induced tissue displacement relates to an acoustic property of the target tissue.

3. A method of claim 2, wherein the data acquired relating to the induced tissue displacement is acquired by administering a plurality of acoustic interrogation pulses to the target tissue site and collecting acoustic data from the target tissue site.

4. A method of claim 2, wherein the data relates to at least one of the magnitude, amplitude and phase of acoustic scatter.

5. A method of claim 1, additionally comprising collecting acoustic data relating to the induced tissue displacement from the target tissue site using an ultrasound transducer operating in at least one of the following modes:

transmission mode, reflection mode, scatter mode, backscatter mode, emission mode, echo mode, Doppler mode, color Doppler mode, harmonic or subharmonic imaging modes, a-mode, b-mode or m-mode; and

correlating the acoustic data relating to the induced tissue displacement with a physiological property of the target tissue.

6. A method of claim 1, wherein the target tissue is CNS tissue.

7. A method of claim 1, wherein the target tissue is CNS tissue, and the physiological property detected is intracranial pressure.

8. A method of claim 1, wherein the target tissue is CNS tissue, and the physiological property detected is cerebral perfusion pressure.

9. A method of claim 1, wherein the target tissue includes or is in proximity to a blood vessel and the physiological property detected is arterial blood pressure.

10. A method of claim 1, wherein the target tissue is CNS tissue, and the physiological property detected is selected from the group consisting of:

vasospasm, stroke, local edema, infection, vasculitus, subdural or epidural hematomas, subarachnoid hemorrhages, ischemic conditions, multiple sclerosis, Alzheimers disease, hypoxic conditions, intracerebral hemorrhage, tumors and other intracranial masses, and acute, chronic and traumatic conditions and injuries.

11. A method of claim 1, wherein the target tissue is heart tissue, and the physiological property detected is abnormal heart tissue.

12. A method of claim 1, wherein the target tissue is peripheral nervous system tissue.

13. A method of claim 1, wherein the data relating to the induced tissue displacement is acquired using a detection technique selected from the group consisting of:

near infrared spectroscopy (NIRS), optical coherence tomography (OCT), magnetic resonance techniques, and positron emission tomography (PET).

14. A method of claim 1, additionally comprising comparing the acquired data relating to the induced tissue displacement with an empirically determined standard.

15. A method of claim 1, additionally comprising acquiring multiple data sets, each data set relating to the induced tissue displacement at different points in time relative to the application of the acoustic radiation force.

16. A method of claim 1, additionally comprising inducing tissue displacement at a second target tissue site different from the first by applying a second ultrasound pulse, acquiring data relating to the induced tissue displacement at or in proximity to the second target tissue site, and comparing the acquired data relating to the tissue displaced at the target tissue site with the acquired data relating to the tissue displaced at the second target tissue site.

17. A method of claim 1, wherein the target tissue is CNS tissue, and wherein the data acquired relating to the induced tissue displacement relates to an acoustic property of the target tissue, additionally comprising conducting an initial environmental assessment to evaluate the characteristics of the environment between an acoustic source and the target tissue site.

18. A method of claim 1, additionally comprising acquiring data relating to intrinsic tissue displacements at the target tissue site at multiple time points over the course of at least one cardiac cycle, and correlating the acquired data relating to the intrinsic tissue displacements and the induced tissue displacement at the target tissue site with a physiological property of the target tissue.

19. A method of claim 1, additionally comprising applying a plurality of different ultrasound pulses to the target tissue site and acquiring data relating to the tissue displacements induced by the different ultrasound pulses.

20. A method of claim 1, additionally comprising applying a plurality of ultrasound pulses to the target tissue site at a plurality of times and acquiring data relating to the induced tissue displacements.

21. A method of claim 1, additionally comprising applying a plurality of ultrasound pulses to a plurality of target tissue sites and acquiring data relating to the induced tissue displacements at the plurality of target tissue sites.

22. A method for assessing a physiological property of a target tissue, comprising acquiring data relating to intrinsic tissue displacements at a target tissue site at multiple time points over the course of at least one cardiac cycle, and relating the intrinsic tissue displacement data with a physiological property of the target tissue.

23. A method of claim 22, additionally comprising acquiring data relating to intrinsic tissue displacements at multiple target tissue sites at multiple time points over the course of at least one cardiac cycle.

24. A method of claim 23, wherein the data acquired relating to the intrinsic tissue displacement at the target tissue site relates to the acoustic properties of the target tissue.

25. A method of claim 24, wherein detected acoustic properties of the target tissue are selected from the group consisting of:

changes in the amplitude of acoustic signals, changes in phase of acoustic signals, changes in frequency of acoustic signals, changes in acoustic emission signals, changes in length of scattered signals relative to an interrogation signal, changes in maximum and/or minimum amplitude of an acoustic signal within a cardiac cycle, the ratio of the maximum and/or minimum amplitude to that of the mean or variance of subsequent oscillations within a cardiac cycle, changes in temporal or spatial variance of scattered signals at different times in the same location and/or at the same time in different locations, and rates of change of tissue displacement or relaxation.

26. A method of claim 22, wherein the data acquired relating to the intrinsic tissue displacement at the target tissue site is acquired by administering acoustic interrogation pulses to the target tissue site and collecting acoustic scatter data.

27. A method of claim 26, wherein acoustic scatter data is acquired at a single acoustic frequency.

28. A method of claim 26, wherein acoustic scatter data is acquired at multiple acoustic frequencies.

29. A method of claim 22, comprising relating the intrinsic tissue displacement data and additional data relating to blood pressure, cardiac and/or respiratory cycles, with a physiological property of the target tissue.

30. A method of claim 22, wherein the data relating to the intrinsic tissue displacement at the target tissue site is acquired using a detection technique selected from the group consisting of:

near infrared spectroscopy (NIRS), optical coherence tomography (OCT), magnetic resonance techniques, and positron emission tomography (PET).

31. A method for detecting a medically relevant physiological property of a target tissue, comprising:

(1) applying an acoustic radiation force to displace the target tissue at a desired target site;

(2) examining at least one aspect of the displacement of the target tissue, or an induced biological response; and

(3) assessing a tissue property as a function of an aspect of displacement of the target tissue or a biological response to the displacement of the target tissue.

32. A method of claim 31, additionally comprising characterizing the acoustic propagation environment by conducting an initial environmental assessment to determine the location and properties of tissue between a detection source and the target tissue prior to applying the acoustic radiation force.

33. A method of claim 31, wherein the data relating to the displacement of the target tissue is acquired using a detection technique selected from the group consisting of:

near infrared spectroscopy (NRS), optical coherence tomography (OCT), magnetic resonance techniques, and positron emission tomography (PET).

34. A method of claim 31, wherein the data acquired relating to the tissue displacement of the target tissue relates to an acoustic property of the target tissue.

37. A method of claim 36, additionally comprising relating the acoustic scatter data to the stiffness or elasticity of the target CNS tissue and relating the stiffness or elasticity of the target tissue with ICP.

38. A method of claim 36, additionally comprising comparing the ICP and ABP and determining the autoregulation status of the patient.

40. A system of claim 39, wherein an acoustic source and an acoustic detector are provided as an ultrasound transducer.

41. A system of claim 39, comprising multiple ultrasound transducers.

42. A system of claim 41, wherein the multiple ultrasound transducers are annular.

43. A system of claim 39, wherein an acoustic source and detector is provided as a transcranial Doppler device.

44. A system of claim 39, wherein the display device provides information relating to the ICP, ABP and autoregulation.

47. A method of claim 46 wherein the physiological condition or biological response is pain and data is acquired by observing the subjective sensation of pain induced, or not, upon application of an ultrasound pulse to each of the targeted tissue sites.

48. A method of claim 47 for localizing the source of pain in a joint.

49. A method of claim 47 for localizing a source of pain and diagnosing a condition selected from the group consisting of:

appendicitis, cholecystitis, pelvic inflammatory disease, lymphadenopathies, anthrax infection, and peripheral nerve-related conditions.

35. A method for assessing a physiological parameter of a target tissue comprising:

applying focused ultrasound and inducing oscillation of the target tissue;

measuring a property of an acoustic signal emitted from the target tissue; and

relating the property of the emitted acoustic signal to a physiological tissue property.

36. A method for monitoring intracranial pressure (ICP) in a subject, comprising:

administering acoustic interrogation signals to a target CNS tissue site in the subject;

acquiring acoustic scatter data from the target CNS tissue site;

determining the arterial blood pressure (ABP) of the subject; and

relating the acquired acoustic scatter data and ABP with ICP.

39. A system comprising an acoustic source and an acoustic detector, the acoustic source and detector being operably connected to a power source, the power source being operably connected to a function generator, and the function generator being operably connected to a controller having data acquisition, storage and analysis capability, the controller having the capability to process acquired acoustic data and relate acquired acoustic data with at least one physiological tissue condition, and the controller being operably connected to a display device for displaying information relating to at least one physiological tissue condition.

45. A system comprising a focused acoustic source capable of providing targeted acoustic pulses in combination with an imaging device capable of imaging the spatial location of the targeted acoustic pulse.

46. A method for localizing a physiological condition or biological response comprising:

administering ultrasound pulses to a plurality of targeted tissue sites and acquiring data relating to the physiological condition or biological response induced by the ultrasound pulse(s) at each of the targeted tissue sites.