OPTICAL MEASUREMENT INSTRUMENT FOR LIVING BODY

• US 20080146901A1
• Filed: 12/12/2007
• Published: 06/19/2008
• Est. Priority Date: 12/15/2006
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: KATURA, Takusige, Maki, Atsushi, Tanaka, Naoki
• Granted Patent: US 8,311,600 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• 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 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: G06F 18/21343 using decorrelation or non-stationarity, e.g. minimising lagged cross-correlations

Abstract

An optical measurement instrument for living body that comprises: a plurality of light irradiation means for irradiating an object being tested with light; a plurality of light reception means for detecting the light that is irradiated to the object being tested and propagates inside the object being tested; and a calculation unit for calculating hemodynamics of a plurality of factors inside the object being tested from the detection signal detected by the light reception means, wherein the calculation unit comprises: a separation calculation unit for separating a plurality of signals from the detection signals; a selection unit for calculating a correlation coefficient between a plurality of the signals separated to select a signal in which a correlation coefficient is a predetermined value or greater as a noise signal; and a reconstruction calculation unit for reconfiguring the detection signal excluding the noise signal selected by the selection unit.

Claims

1. An optical measurement instrument for a living body, comprising:

a plurality of light irradiation means for irradiating an object being tested with light;

a plurality of light reception means for detecting the light that is irradiated to said object being tested and propagates inside said object being tested; and

a calculation unit for calculating hemodynamics of a plurality of factors inside said object being tested from the detection signal detected by said light reception means,

wherein said calculation unit comprises;

a separation calculation unit for separating a plurality of signals from said detection signal;

a selection unit for calculating a correlation coefficient between a plurality of said signals separated by said separation calculation unit to select a signal in which said correlation coefficient is a predetermined value or greater as a noise signal; and

a reconstruction calculation unit for reconfiguring the detection signal excluding the noise signal selected by said selection unit.

2. The optical measurement instrument for a living body according to claim 1, wherein said separation calculation unit uses an independent component analysis method to separate a plurality of signals from said detection signal.

3. The optical measurement instrument for a living body according to claim 2, wherein said selection unit calculates a correlation coefficient for each mixing coefficient matrix among the mixing coefficient matrices that each corresponds to a plurality of separation signals calculated by said separation calculation unit using an independent analysis method, and selects a signal in which said correlation coefficient is a predetermined value or greater as a noise signal.

4. The optical measurement instrument for a living body according to claim 3, wherein the correlation coefficient between a plurality of factors is calculated for said mixing coefficient matrices that are binarized by a predetermined threshold, and a signal in which said correlation coefficient is a predetermined value or greater is selected as the noise signal.

5. The optical measurement instrument for a living body according to claim 1, wherein said reconstruction calculation unit performs reconstruction by calculating the mixing coefficient matrices of the noise signal selected by said selection unit as zero.

6. The optical measurement instrument for a living body according to claim 2, wherein said independent component analysis method is a TDDICA method.

7. The optical measurement instrument for a living body according to claim 1, wherein filtering processing is performed before said separation calculation unit performs the separation calculation.

8. The optical measurement instrument for a living body according to claim 1, wherein said selection unit extracts a separation component that has a high correlation with the time of the assignment given to said object being tested from the result of separation performed by said separation calculation unit to thereby perform said selection from the extraction result.

9. The optical measurement instrument for a living body according to claim 1, wherein said selection unit calculates an instantaneous phase from the separation signals separated by said separation calculation means, selects a signal in which the phase difference between oxygenated hemoglobin and deoxygenated hemoglobin is smaller than a first predetermined value as a body motion noise, and selects a signal in which said difference between the oxygenated hemoglobin and deoxygenated hemoglobin is within a range of a second predetermined value as a brain activity signal.