Brain function measurement device, brain function measurement method, and brain function measurement program

• US 20050272988A1
• Filed: 12/03/2004
• Published: 12/08/2005
• Est. Priority Date: 06/07/2004
• Status: Active Grant

• Current Assignee: National Institute of Information and Communications Technology
• Original Assignee: National Institute of Information and Communications Technology
• Inventors: Eda, Hideo
• Granted Patent: US 7,239,903 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• 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 5/14553 specially adapted for cerebral tissue

Abstract

In addition to irradiating examination light toward the inside of the bead of the subject and detecting the examination light reflected from the head: structural data indicating the head structure, wherein the head is divided into multiple materials and the various materials are further divided into multiple elements, are stored in a structural data storage unit set up in a specified region of memory; the optical properties of the aforementioned elements are calculated from a given specified initial value; the hemodynamics inside the brain of the subject are calculated based on the optical properties thereof, and the aforementioned initial values are taken to be the optical properties when the light intensity signal values, provisionally calculated from optical properties under the assumption that the optical properties are uniform for each of the aforementioned materials, are in a fixed range of the actually measured light intensity signal values.

Claims

1. A brain function measurement device, which uses a light irradiation means that irradiates examination light toward the inside of the head of a subject, and a light receiving means that receives the examination light exiting from the head and outputs light intensity signals indicating the light intensity thereof,

comprising a structural data storage unit that stores structural data indicating the head structure wherein the head is divided into multiple materials, and the various materials are further divided into multiple elements,

an optical properties and hemoglobin parameters calculator that calculates optical properties of the aforementioned elements from given specified initial values, and calculates the hemoglobin parameters inside the brain of the subject based on the optical property values thereof, and

an initial values calculator that calculates the aforementioned initial values;

characterized in that the initial values calculator thereof provisionally stipulates the optical property values of the various materials under the assumption that the optical properties are uniform for each material, and takes the aforementioned initial values to be the provisional optical properties when the light intensity signal values calculated from these provisional optical properties are in a fixed range of the actually measured light intensity signal values.

2. A brain function measurement device according to claim 1 in which the aforementioned initial values calculator successively updates the aforementioned provisional optical properties by taking the input specified values as the point of departure such that the light intensity signal values calculated based on these values approach the aforementioned actually measured light intensity signal values.

3. A brain function measurement device according to claims 1 in which the aforementioned structural data classifies the head into the five materials of the scalp, skull, CSF, gray matter, and white matter.

4. A brain function measurement device according to claims 1 in which the aforementioned structural data is obtained by actual measurements of the head of the subject

5. A brain function measurement device according to claims 1 in which the aforementioned structural data is taken to be what is commonly obtained from a general model.

6. A brain function measurement device according to claims 1 in which the aforementioned examination light is near infrared light of specified multiple wavelengths.

7. A brain function measurement method comprising the steps of:

irradiating light using light irradiation means to irradiate examination light toward the inside of the head of the subject;

receiving light using light receiving means to receive examination light exiting from the head, and to output light intensity signals that indicate the light intensity thereof;

storing structural data via storage in a structural data storage unit set up in a specified region of memory structural data indicating the head structure wherein the head is divided into multiple materials, and then the various materials are further divided into multiple elements;

calculating the optical properties of the various aforementioned elements from given specified initial values, and calculating the hemoglobin parameters in the brain of the subject based on the optical properties thereof; and

calculating initial values taking the aforementioned initial values to be the various optical properties when the optical intensities calculated from the optical properties, provisionally stipulated under the assumption that the optical properties are uniform for each material, are in a fixed range of the actually measured light intensity signal values.

8. A brain function measurement method according to claim 7 wherein the aforementioned initial values calculation step is conducted such that the light intensity signal values calculated based on the aforementioned provisional optical properties approach the actually measured light intensity signal values, and such that the aforementioned initial values are calculated by successively updating the specified values input as the point of departure.

9. A brain function measurement program, which uses a light irradiation means that irradiates examination light toward the inside of the head of the subject, and a light receiving means that receives the examination light exiting from the head and outputs light intensity signals indicating the light intensity thereof, characterized in that a computer manifests the functions of:

a structural data storage unit that stores structural data indicating the head structure wherein the head is divided into multiple materials, and the various materials are further divided into multiple elements;

an optical properties and hemoglobin parameters calculator that calculates optical properties of the aforementioned elements from given specified initial values, and calculates the hemoglobin parameters inside the brain of the subject based on the optical properties thereof, and

an initial values calculator that provisionally stipulates the optical properties of the various materials under the assumption that the optical properties are uniform for each material, and that takes the aforementioned initial values to be the provisional optical properties when the light intensity signal values calculated from these provisional optical properties are in a fixed range of the actually measured light intensity signal values.

10. A brain function measurement program according to claim 9 in which the aforementioned initial values calculator successively updates the aforementioned provisional optical properties by taking the input specified values as the point of departure such that the light intensity signal values calculated based these values approach the aforementioned actually measured light intensity signal values.