Optical measurement apparatus for living body
View Patent ↗A principal component analysis or an independent component analysis is conducted on the living body signals, e.g., local cerebral blood amount change signals obtained by the living body optical measurement to extract and display multiple component signals thereof. Signals other than the component signals containing noise are selected from these component signals automatically or manually, and the local cerebral blood amount change signals are reconstructed by using selected signals. The reconstructed signals is displayed and further subjected to the component analysis or the reconstruction as appropriate, and used for the profiling of information necessary for the diagnosis. Consequently, high-precision target signals can be obtained by completely removing external noise included in the living body signals, particularly the noise which cannot be adequately removed by the moving average and the filtering processings.
1. An optical measurement apparatus for living body comprising a means for irradiating visible to infrared light onto an object to be examined, a means for detecting light transmitted inside said object and generates signals corresponding to the detected amount of light, a signal processing means for processing the signals and generating biological signals of the object to be examined and a display means for displaying the biological signals generated by said signal processing means;
wherein said signal processing means comprises at least one signal separating means for separating the biological signals into multiple component signals, a signal selecting means for selecting specified component signals based on correlation values between component signals and a pre-determined reference waveform signal that represents a characteristic of living-body reaction of the examined object, and a signal reconstruction means for reconstructing the biological signals by using the selected specified component signals, excluding those containing noise, of said multiple component signals.
2. The optical measurement apparatus for living body according to claim 1 , wherein said displaying means displays separated component signals and reconstructed signals, respectively.
3. The optical measurement apparatus for living body according to claim 1 , wherein said signal processing means comprises at least two different signal separating means.
4. The optical measurement apparatus for living body according to claim 1 , wherein at least one of said at least one signal separating means analyzes the principal components of said biological signals and separates them into multiple component signals.
5. The optical measurement apparatus for living body according to claim 1 , wherein at least one of said at least one signal separating means analyzes the independent components of said biological signals and separates them into multiple component signals.
6. The optical measurement apparatus for living body according to claim 1 , wherein said signal selecting means further selects the specified component signals based on the standard deviations of differential waveforms of the component signals.
7. The optical measurement apparatus for living body according to claim 1 , wherein signal processing means comprises a user interface means with which users can select the selected specified component signals to be used by said signal reconstructing means.
8. The optical measurement apparatus for living body according to claim 1 , wherein multiple principal component waveforms or independent component waveforms and a selecting box for selecting the multiple principal component waveforms or independent component waveforms are displayed.
9. The optical measurement apparatus for living body according to claim 1 , wherein a correlation value box for inputting the correlation value and/or a standard deviation box for inputting the standard deviation are displayed in said display means.
10. An optical measurement apparatus for living body comprising a means for irradiating visible to infrared light onto multiple positions of an object to be examined, a means for detecting a light irradiated from said multiple positions and transmitted inside the object and generating measurement signals at multiple measurement points which are defined by the irradiating and detecting positions, a signal processing means for processing measurement signals detected by said detection means and generating waveforms indicating changes of substance inside the object at the multiple measurement points and a display means for displaying the results of processing by said signal processing means;
wherein said signal processing means comprises a signal separating means for separating the waveforms into multiple component waveforms, a signal selecting means for selecting specified component signals based on correlation values between component signals and a pre-determined reference waveform signal that represents a characteristic of living-body reaction of the examined object, and a signal reconstruction means for reconstructing waveforms representing changes in substance inside said object to be examined by using the selected specified component waveform among the multiple component waveforms.
11. A method of removing noise from the optical measurement signals of living body obtained by irradiating a light onto the examination site of an object to be examined and detecting a light transmitted through said examination site, comprises
a step of analyzing components of the optical measurement signals and separating them into multiple component signals,
a step of selecting specified component signals based on correlation values between component signals and a predetermined reference waveform signal, wherein the predetermined reference waveform signal represents a characteristic of living-body reaction of the examined object, and
a step of reconstructing optical measurement signals by using specified component signals among the separated multiple component signals.
12. The method of removing noise according to claim 11 , wherein the step of separating measured signals into the multiple component signals comprises a step of performing a principal component analysis of the multiple component signals.
13. The method of removing noise according to claim 11 or 12 , wherein the step of separating measured signals into the multiple component signals comprises a step of performing an independent component analysis of the multiple component signals.
14. The method of removing noise according to claim 11 or 12 , which comprises a step for separating the optical measurement signals reconstructed by said reconstruction step into the multiple component signals and a step for reconstructing signals.
15. The method of removing noise according to claim 11 or 12 , which comprises a step for selecting specified component signals from multiple separated component signals.
16. The method of removing noise according to claim 15 , wherein the specified component signals are further selected by using correlation values between the component signals and a pre-determined reference signal and/or standard deviations of differential waveforms of the component signals in said selecting step.