Optical system for measuring metabolism in a body and imaging method

• US 7,715,904 B2
• Filed: 01/19/2005
• Issued: 05/11/2010
• Est. Priority Date: 10/06/1994
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ito, Yoshitoshi, Yamashita, Yuichi, Maki, Atsushi, Koizumi, Hideaki, Kawaguchi, Fumio
• Primary Examiner(s): Le; Long V
• Assistant Examiner(s): Cheng; Jacqueline
• Application Number:
  US11/037,339
• Publication Number:
  US 20050131303A1
• Time in Patent Office: 1,938 Days
• Field of Search: 600/476, 600/473, 600/310, 250/330
• US Class Current: 600/476
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/0042 for the brain
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/7228 Signal modulation applied to the input signal sent to patient or subject; demodulation to recover the physiological signal modulation H03C
• CPC Class Codes: A61B 6/03 Computed tomography [CT] echo-tomography A61B8/14
• CPC Class Codes: A61B 6/507 for determination of haemodynamic parameters, e.g. perfusion CT

Abstract

In an optical measurement system and imaging method adapted to measure in vivo information in a living body without harming the living body, light rays of a plurality of wavelengths which are modulated in intensity with a plurality of different frequencies are irradiated on a plurality of irradiation positions on the surface of a living body, and time-variable changes in living body transmitting light intensity levels corresponding to the respective wavelengths and the respective irradiation positions are measured at different positions on the surface of the living body. Light is utilized to image the results of the measurements, in which the measuring time is shortened by estimating fluctuation attributable to the living body, and the presence or absence of a change in measured signal can be decided easily by displaying an estimation signal and a measured signal at a time.

Claims

1. A living body optical measurement system comprising:

an irradiation unit adapted to irradiate light on a living body while alternately setting loading time during which load is applied to the living body and unloading time during which load is not applied to the living body,

a measurement unit adapted to measure the living body transmitting light intensity by irradiating the light on the living body to obtain a measured signal,

an arithmetic unit adapted to calculate a signal which corresponds to the fluctuation due to hemodynamic movement in the living body during a relaxation time,

wherein the relaxation time is the time during which the signal has time to recover its intact form following the loading time and in which influence by application of the load remains during the unloading time, and

wherein the calculation is done by eliminating the measured signal from the relaxation time and fitting a predetermined function, through use of a method of least squares, to the remaining unloading-time portions of the measured signal, and

a display unit adapted to display a result calculated by said arithmetic unit.

2. A living body optical measurement system according to claim 1, wherein said arithmetic unit is adapted to calculate a difference between the measured signal and the obtained signal due to the change in the hemodynamic movement, to display the difference by said display unit.

3. A living body optical measurement system according to claim 1, wherein said display unit is adapted to display the measured signal and the obtained signal due to the change in the hemodynamic movement.

4. A living body optical measurement system according to claim 1, wherein said display unit is adapted to display a mark indicative of a starting point of applying said load and a mark indicative of an end point of applying said load in the form of straight lines.

5. A living body optical measurement system according to claim 1,

wherein said arithmetic unit is adapted to perform calculation for determining time-variable changes of relative change amounts of concentration of hemoglobin oxide and reduced hemoglobin, due to said load on the basis of the measured signal and the obtained signal due to the change in the hemodynamic movement, and

wherein said display unit is adapted to display the time-variable changes of relative change amounts of concentration of hemoglobin oxide and reduced hemoglobin, determined by said arithmetic unit.

6. A living body optical measurement system according to claim 5,

wherein said arithmetic unit is adapted to perform the calculation for determining a time integral value in each of the loading time or a mean value in each of the loading time, of each of time-variable changes of the relative change amounts of the hemoglobin oxide and the reduced hemoglobin, and

wherein said display unit is adapted to display the time integral value and the mean value.

7. A living body optical measurement system comprising:

an irradiation unit adapted to irradiate light on a living body while alternately setting loading time during which load is applied to the living body and unloading time during which load is not applied to the living body,

a measurement unit adapted to measure the living body transmitting light intensity by irradiating the light on the living body to obtain a measured signal,

an arithmetic unit adapted to calculate a signal which corresponds to the fluctuation due to hemodynamic movement in the living body during a relaxation time,

wherein the relaxation time is the time during which the signal has time to recover its intact form following the loading time and in which influence by application of the load remains during the unloading time, and

wherein the calculation is done by eliminating the measured signal from the relaxation time and fitting a predetermined function, through use of a method of least squares, to the remaining unloading-time portions of the measured signal, and

a display unit adapted to display a result calculated by said arithmetic unit,

wherein said arithmetic unit is adapted to perform said fitting to the measured signal during two unloading times before and after each loading time from which the measured signal during the relaxation time is eliminated.

8. A living body optical measurement system comprising:

an irradiation unit adapted to irradiate light on a living body while alternately setting loading time during which load is applied to the living body and unloading time during which load is not applied to the living body,

a measurement unit adapted to measure the living body transmitting light intensity by irradiating the light on the living body to obtain a measured signal,

an arithmetic unit adapted to calculate a signal which corresponds to the fluctuation due to hemodynamic movement in the living body during a relaxation time,

wherein the relaxation time is the time during which the signal has time to recover its intact form following the loading time and in which influence by application of the load remains during the unloading time, and

wherein the calculation is done by eliminating the measured signal from the relaxation time and fitting a predetermined function, through use of a method of least squares, to the remaining unloading-time portions of the measured signal, and

a display unit adapted to display a result calculated by said arithmetic unit,

wherein said arithmetic unit is adapted to perform said fitting to the measured signal during a plurality of unloading times from which the measured signal during the relaxation time is eliminated.

9. A living body optical measurement system comprising:

a plurality of light sources adapted to simultaneously irradiate a plurality of light rays having wavelengths different from each other on a head of a living body,

a detector unit adapted to detect intensities of the light rays after the light rays irradiated on the head of the living body are transmitted through the living body, and adapted to separate the living body transmitting light rays with respect to each wavelength to measure the intensity of the separated light to obtain a measured signal with respect to each wavelength,

an arithmetic unit adapted to perform calculation for obtaining a signal due to a change in hemodynamic movement in the head with respect to each wavelength on a basis of a detected result of said detector unit,

a display unit adapted to display calculated results of said arithmetic unit, and

an input unit,

wherein said arithmetic unit is adapted to calculate a signal which corresponds to the fluctuation due to hemodynamic movement in the head during a relaxation time,

wherein the relaxation time is the time during which the measured signal has time to recover its intact form following the loading time and in which influence by application of the load remains during the unloading time, and

wherein the calculation is done by eliminating the measured signal from the relaxation time and fitting a predetermined function, through use of a method of least squares, to the remaining unloading-time portions of the measured signal, and

wherein said display unit displays the signal due to the change in hemodynamic movement in the head calculated by said arithmetic unit and said measured signal.

10. A living body optical measurement system comprising:

a plurality of light sources adapted to irradiate a plurality of light rays having wavelengths different from each other on a living body,

a detector unit adapted to detect intensities of the light rays after the light rays from said light sources irradiated on the living body, are transmitted through the living body, to obtain a plurality of measured signals,

a computer adapted to calculate a signal which corresponds to the fluctuation due to hemodynamic movement in the living body during a relaxation time,

wherein the relaxation time is the time during which the plurality of measured signals have time to recover its intact form following the loading time and in which influence by application of the load remains during the unloading time, and

wherein the calculation is done by eliminating the plurality of measured signals from the relaxation time and fitting a predetermined function, through use of a method of least squares, to the remaining unloading-time portions of the plurality of measured signals, and

a display unit adapted to display results calculated by said computer.

11. A living body optical measurement system according to claim 10,

wherein said computer is adapted to calculate a difference between the measured signal of said detector unit and the fluctuation signals of the living body calculated by said computer, and

wherein said display unit is adapted to display the difference.

12. A living body optical measurement system according to claim 10, wherein said display unit is adapted to display the measured signal of said detector unit and the fluctuation signals of the living body, calculated by said computer.

13. A living body optical measurement system according to claim 10, wherein said display unit is adapted to display a mark indicative of a starting point of applying said load, and a mark indicative of an end point of applying said load, in the form of straight lines.

14. A living body optical measurement system according to claim 10,

wherein said computer is adapted to perform calculation for determining time-variable changes of relative change amounts of concentration of hemoglobin oxide and reduced hemoglobin, due to said load on a basis of the measured signal and the obtained said fluctuation signals of the living body, and

wherein said display unit is adapted to display the time-variable changes of relative change amounts of concentration of hemoglobin oxide and reduced hemoglobin, determined by said computer.

15. A living body optical measurement system according to claim 14,

wherein said computer is adapted to perform the calculation for determining a time integral value in each of the loading time, or a mean value in each of the loading time, of each of time-variable changes of the relative change amounts of the hemoglobin oxide and the reduced hemoglobin, and

wherein said display unit is adapted to display the time integral value and the mean value.

16. A living body optical measurement system comprising:

a plurality of light sources adapted to irradiate a plurality of light rays having wavelengths different from each other on a living body,

a detector unit adapted to detect intensities of the light rays after the light rays from said light sources irradiated on the living body, are transmitted through the living body, to obtain a plurality of measured signals,

a computer adapted to calculate a signal which corresponds to the fluctuation due to hemodynamic movement in the living body during a relaxation time,

wherein the relaxation time is the time during which the plurality of measured signals have time to recover its intact form following the loading time and in which influence by application of the load remains during the unloading time, and

wherein the calculation is done by eliminating the plurality of measured signals from the relaxation time and fitting a predetermined function, through use of a method of least squares, to the remaining unloading-time portions of the plurality of measured signals, and

a display unit adapted to display results calculated by said computer,

wherein said computer is adapted to perform fitting through use of a method of least squares to the measured signal in two unloading times before and after each of the loading time and not including the relaxation time.

17. A living body optical measurement system comprising:

a plurality of light sources adapted to irradiate a plurality of light rays having wavelengths different from each other on a living body,

a detector unit adapted to detect intensities of the light rays after the light rays from said light sources irradiated on the living body, are transmitted through the living body, to obtain a plurality of measured signals,

a computer adapted to calculate a signal which corresponds to the fluctuation due to hemodynamic movement in the living body during a relaxation time,

wherein the relaxation time is the time during which the plurality of measured signals have time to recover its intact form following the loading time and in which influence by application of the load remains during the unloading time, and

wherein the calculation is done by eliminating the plurality of measured signals from the relaxation time and fitting a predetermined function, through use of a method of least squares, to the remaining unloading-time portions of the plurality of measured signals, and

a display unit adapted to display results calculated by said computer,

wherein said computer is adapted to perform fitting through use of a method of least squares to the measured signal in a plurality of unloading times, from which the measured signal in the relaxation time is removed.