JP2011092220A - Apparatus and method for discriminating biological tissue - Google Patents

Abstract

An object of the present invention is to provide a biological tissue identification apparatus and method capable of identifying normality / abnormality (tumor) of biological tissue based on spectrum information with high accuracy without using a fluorescent substance.
Infrared spectrum acquisition means (1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 13, 14) for acquiring infrared spectrum information from a living tissue, and the infrared spectrum A biological tissue identification device having a computing means (11) for identifying normality / abnormality of the biological tissue based on the infrared spectrum information obtained by the obtaining means, wherein the computing means (11) It is characterized in that normality / abnormality of a living tissue is identified based on a statistic representing a change in infrared spectrum information in the wavelength direction in whole or in part.
[Selection] Figure 2

Description

  The present invention relates to a biological tissue identification device and method for identifying whether a biological tissue is a normal tissue or an abnormal tissue (such as a tumor) based on infrared spectrum information.

  Attempts to distinguish normal tissue and malignant tumors from hyperspectral endoscopic images in the visible light region as a conventional technique for distinguishing normality / abnormality of biological tissue from spectral information has been proposed by M E. Martin et al. Reference 1). However, in the method of Non-Patent Document 1, since only the visible light region is observed and there is no means for safely introducing illumination light having the intensity required for hyperspectral observation into the body, only the spectral change of reflectance is detected. However, no significant difference has been found. For this reason, an indirect method of injecting a fluorescent substance porphyrin that is specifically absorbed by a tumor and observing the fluorescence generated thereby has been shown to be effective in animal experiments. However, since porphyrin is phototoxic, it is dangerous to administer high concentrations to the human body. In Non-Patent Document 2, a diagnostic index for ulcers derived from diabetes is calculated from a visible-spectrum hyperspectral image of a living body. In this method, the absorption characteristics of oxyhemoglobin and deoxyhemoglobin that differ in the vicinity of 600 nm to 800 nm are revealed. Therefore, the diagnosis of the microcirculation of the affected area is performed, and the inherent malignancy of the tissue cannot be evaluated.

M E. Martin et al .: “Development of an Advanced Hyperspectral Imaging (HSI) System with Application for Cancer Detection”, Annals of Biomedical Engineering, Vol.34, No.6, pp.1061-1068 (2006) L. Khaodhiar et al .: ”The Use of Medical Hyperspectral Technology to Evaluate Microcirculatory Changes in Diabetic Foot Ulcers and to Predict Clinical Outcomes, Diabetes Care, Vol.30, No.4, pp.903-910 (2007)

  As described above, the conventional tumor identification technology uses visible light spectrum information as spectrum information, and thus is easily affected by blood (particularly hemoglobin), and it is difficult to obtain spectrum information of the living tissue itself. In order to make it easy to obtain information on the living tissue itself, a fluorescent substance is administered to a patient, but the fluorescent substance itself may not be preferable for the human body. Moreover, since the fluorescent substance must be administered to the patient in advance, the burden on the patient is great.

  An object of the present invention is to solve the above-mentioned problems and to provide a biological tissue identification apparatus and method that can identify normal / abnormal (tumor) of biological tissue based on spectrum information with high accuracy without using a fluorescent substance. To do.

In order to achieve the above object, the present invention has the following means.
The first means identifies infrared spectrum acquisition means for acquiring infrared spectrum information from the biological tissue, and normality / abnormality of the biological tissue based on the infrared spectrum information obtained by the infrared spectrum acquisition means A calculating means for calculating the biological tissue, wherein the infrared spectrum information is infrared spectrum information in a wavelength range of 1220 to 1380 nm (excluding 1255-1285 nm); A biological tissue identification device that identifies normality / abnormality of the biological tissue based on a statistic representing a change in infrared spectrum information in the wavelength direction in all or part of the range.
According to the first means, whether a living tissue is normal or abnormal (such as a tumor) based on infrared spectrum information in a wavelength range of 1220 to 1380 nm (excluding 1255-1285 nm) without using a fluorescent substance. Is possible with high accuracy. Since infrared light, particularly infrared light having a wavelength of 1220 to 1380 nm (excluding 1255-1285 nm) is used, it is difficult to be influenced by absorption of hemoglobin in the blood, and spectral information of the tissue itself can be obtained.

  As a result of actually measuring and comparing the infrared spectrum information of normal tissue and abnormal tissue (tumor, cancer tissue, etc.), the present inventor found that in the wavelength region of 1220-1380 nm (excluding 1255-1285 nm) We obtained knowledge that non-uniformity in the wavelength direction of the pixel can be manifested by evaluating based on a statistic calculated from a difference or the like. As shown in the example of the graph of the infrared spectrum information of the normal tissue and the abnormal tissue (gastric cancer tissue) actually measured in FIG. 1, when comparing a plurality of pathological samples in the vicinity of 1220 to 1380 nm, Infrared reflectance spectrum patterns are almost the same, but large undulations (low frequency components) for tumor tissue do not show a consistent trend, but fine fluctuations from channel to channel (high frequency components) Was significantly observed for all tumor samples. The present invention evaluates this infrared spectral variation based on statistics representing changes in all or part of the 1220-1380 nm wavelength range, particularly excluding the 1255-1285 nm region, to increase accuracy. Thus, an abnormal tissue and a normal tissue are identified.

The second means identifies abnormal tissue and normal tissue based on the absolute value of the difference between the infrared spectrum information in the wavelength direction.
According to the second means, the difference in the fluctuation component of the spectrum information between the normal tissue and the abnormal tissue and the difference in the spectrum pattern between the normal tissue and the abnormal tissue obtained by the inventor's experiment are particularly in this wavelength range. Since it is based on the knowledge that it is remarkable, it becomes possible to identify normality / abnormality of a living tissue with high accuracy.

The third means is for discriminating between an abnormal tissue and a normal tissue based on a sum of squares of differences in infrared spectrum information in the wavelength direction.
According to the third means, the difference in the fluctuation component of the spectral information between the normal tissue and the abnormal tissue and the difference in the spectral pattern between the normal tissue and the abnormal tissue obtained by the inventor's experiment are particularly in this wavelength range. Since it is based on the knowledge that it is remarkable, it becomes possible to identify normality / abnormality of a living tissue with high accuracy.

  A fourth means is any one of the first to third means, wherein the infrared spectrum acquisition means acquires infrared spectrum information of a living tissue in a living body with an endoscope. Device.

A fifth means is the biological tissue identification device according to any one of the first to third means, wherein the biological tissue identified as abnormal by the computing means is a digestive system tumor.
According to the fifth means, based on the knowledge obtained by the experiment of the present inventor that the normal / abnormal discrimination of the living tissue of the present invention is particularly effective for the identification of gastrointestinal tumors such as gastric cancer. Therefore, it becomes possible to identify the digestive system tumor with high accuracy.

  The sixth means determines normality / abnormality of the biological tissue based on infrared spectrum information in the wavelength range of 1220 to 1380 nm (excluding 1255-1285 nm) from the biological tissue obtained by the infrared spectrum acquisition means. A biological tissue identification method for identifying a statistic of infrared spectrum information in a wavelength direction in all or a part of the wavelength range of the infrared spectrum information, and a change in the infrared spectrum information. Identifying the normality / abnormality of the biological tissue based on a statistic to be expressed.

  According to the present invention, normal / abnormal (tumor) of living tissue can be identified with high accuracy based on infrared spectrum information without using a fluorescent substance. Since spectrum information of infrared light is used as spectrum information, it is difficult to be affected by blood (particularly hemoglobin), and it is easy to acquire spectrum information of the living tissue itself without using a fluorescent substance. Since no fluorescent substance is used, the human body is less affected and the inspection is simplified.

The graph which shows the reflectance spectrum of a normal cell tissue, and the reflectance spectrum of a malignant tumor tissue in an infrared region. The figure which showed the structure of the biological tissue identification device which is one Embodiment of this invention. << FIG. 2A >> Whole block diagram. << FIG. 2B >> The figure which showed the structure in the case of using a linear variable filter. << FIG. 2C >> The figure which showed the structure in the case of using a grism. In order to detect a tumor region on the inner wall of the stomach using an embodiment of the present invention, the absolute value of the difference in the infrared spectrum information in the wavelength region excluding 1255-1285 nm from the wavelength band of interest (1220-1380) is averaged Image. In order to detect the tumor region of the stomach inner wall using an embodiment of the present invention, the sum of squares of the difference in the infrared spectrum information in the wavelength region excluding 1255-1285 nm from the wavelength band of interest (1220-1380) is represented. image. The figure which showed the comparison with the identification result by the embodiment of this invention, and a pathological test result.

  Below, the apparatus etc. which concern on each embodiment of this invention are demonstrated. First, an apparatus capable of sweeping the wavelength and discriminating normality / abnormality of a living tissue from a change in reflection luminance with time will be described with reference to FIG. 2A.

  This device changes the center wavelength of narrow-band illumination light with a bandwidth of 5 nm in the range of 1225 nm to 1375 nm, and determines the degree of non-uniformity in the wavelength direction at each pixel from continuous images acquired at intervals of 5 nm. Evaluation is performed based on the intensity of the external reflection spectrum, and an image is formed.

  In FIG. 2A, the femto wave infrared light source 1 is generally called an SC light source. When a femtosecond infrared monochromatic laser is incident on a highly nonlinear optical fiber, the monochromatic laser beam is converted into broadband white light by a non-linear optical effect called self-phase modulation. Here, wavelength conversion is performed by a nonlinear optical fiber using a femtosecond laser having a wavelength of 1550 nm as a seed light source, and white light having a wavelength of 1100 to 2500 nm is obtained. The light generated by the femtowave infrared light source 1 is developed on the surface of the movable slit 3 by the spectrometer 2. The movable slit 3 is driven by the electrostatic actuator 4 in a triangular wave shape, and light having a half-value width of 5 nm and a center wavelength of 1225 to 1375 nm is extracted from the continuous spectrum 1220 to 1380 nm. Guided to the outer fiber 6. The image of the observation object 7 illuminated with this light is converted into an electrical signal by an infrared CCD camera 9 through an infrared fiber scope 8 composed of an infrared multi-core fiber and an objective lens, and passes through an image input board 10. Guided to the arithmetic unit 11.

  The arithmetic device 11 averages the results calculated based on the arithmetic method described later for the past 45 frames, and displays them on the image display device 12. In addition, a clock signal is sent to the control circuit 13 of the electrostatic actuator 4 so that a wavelength change of 5 nm can be obtained for each screen input in synchronization with the image capture of the image input board 10. That is, a symmetric triangular wave with a period of 0.75 seconds is output from the control circuit 13, and the amplitude of the variable attenuator R (14) is such that the output light center wavelength from the movable slit 3 is 1225-1375 nm. It is adjusted with.

Further, instead of the spectroscope 2, the movable slit 3, and the electrostatic actuator 4 in the apparatus, a linear variable filter (LVF) 23 and an LVF driving motor 24 as shown in FIG. 2B may be used. In general, the linearity is better and alignment is easier than a spectroscope. In FIG. 2B, two collimating lenses 22 are used for both the fiber (light source side) 20 and the fiber (for illumination) 21, but only one may be provided on the fiber (for illumination) 21 side. .
Similarly, a grism 26 as shown in FIG. 2C may be used. By including the grating 25, the grism 26 can shorten the distance to the collimating lens 22.

According to this apparatus, since the wavelength band on the illumination side can be set sufficiently narrow, the irradiation energy applied to the observation object 7 can be suppressed sufficiently low, and the wavelength band on the light receiving side is limited. Compared with the hyperspectral endoscope, the thermal influence on the observation object can be greatly reduced. This is effective for preventing damage to the tissue, particularly in endoscopy, although high intensity illumination is usually required for hyperspectral imaging.
In addition, since the wavelength difference is handled as image information, the image buffer and the calculation mechanism can be simplified as compared with the normally used hyperspectral image processing apparatus, and observation with excellent real-time performance is realized. In this example, the image acquisition is 1 frame 1/60 sec. However, the real-time characteristics can be improved by using a high-speed imaging camera or changing the averaging of the difference amount to an exponential weighted average. It can also be increased.
In addition, by scanning only the wavelength range that is optimal for tumor detection, even in an example using a standard image acquisition board, one image can be formed in 1.3 seconds, further improving real-time performance. Yes, it has superiority at the surgical site.

  The infrared spectrum acquisition means of the present invention includes a femto wave infrared light source 1, a spectrometer 2, a movable slit 3, an electrostatic actuator 4, a condensing lens 5, an infrared fiber for illumination 6, an infrared fiber scope 8, Corresponding to the infrared CCD camera 9, the image input board 10, the control circuit 13, and the variable attenuator R14, the computing means corresponds to the computing device 11, the infrared light source is the femto wave infrared light source 1, the spectrometer 2, the movable slit. 3, the electrostatic actuator 4, the condenser lens 5, and the illumination infrared fiber 6.

  Next, calculation means for identifying normality / abnormality of the living tissue based on the infrared spectrum information obtained by the infrared spectrum acquisition means in the present invention will be described.

<First Embodiment>
In the present embodiment, the differential (difference) in the wavelength direction in the hyperspectral data space is preferentially evaluated, and the difference in the infrared spectrum information in the wavelength region excluding 1255-1285 nm from the wavelength band of interest (1220-1380 nm). By averaging the absolute values, non-uniformity in the wavelength direction of the pixel becomes obvious. The result of applying such a process to the HS image of the stomach inner wall with tumor is shown in FIG. The white area on the figure is the tumor tissue, and the black area is the normal tissue, which is almost consistent with the pathological examination result.

Second Embodiment
In the present embodiment, the differential (difference) in the wavelength direction in the hyperspectral data space is preferentially evaluated, and the difference in the infrared spectrum information in the wavelength region excluding 1255-1285 nm from the wavelength band of interest (1220-1380 nm). By averaging the sum of squares, the non-uniformity in the wavelength direction of the pixel becomes obvious. FIG. 4 shows the result of applying such processing to the HS image of the stomach inner wall with a tumor. The white area on the figure is the tumor tissue, and the black area is the normal tissue, which is almost consistent with the pathological examination result.

  FIG. 5 is a diagram showing a comparison between the identification result and the pathological examination result according to the embodiment of the present invention in order to evaluate the detection accuracy of the tumor tissue according to the present invention. The uppermost row shows a site where a relatively whitish portion is identified as a tumor tissue in the second embodiment. The second row shows, for reference, a site identified as a tumor tissue when the wavelength region of 1255-1285 nm is not removed. The third row shows a site determined to be a malignant tumor tissue based on the pathological examination result of the tissue cross section of the tumor tissue. The fourth and fifth stages are binarized results of the first and second stages. As described above, it can be seen that evaluation by removing the wavelength range from 1255-1285 nm improves the distinguishability of the tumor tissue. When the third and fourth stages are compared, it can be seen that the present embodiment shows good agreement with the pathological examination result.

DESCRIPTION OF SYMBOLS 1 Femto wave infrared light source 2 Spectrometer 3 Movable slit 4 Electrostatic actuator 5 Condenser lens 6 Infrared fiber for illumination 7 Observation object 8 Infrared fiber scope 9 Infrared CCD camera 10 Image input board 11 Arithmetic unit 12 Image Display device 13 Control circuit 14 Variable attenuator R
20 Fiber (light source side)
21 Fiber (for lighting)
22 Collimating lens 23 Linear variable filter (LVF)
24 LVF drive motor 25 Grating 26 Grism

Claims (6)

Infrared spectrum acquisition means for acquiring infrared spectrum information from biological tissue;
Based on the infrared spectrum information obtained by the infrared spectrum acquisition means, a biological tissue identification device having a computing means for identifying normality / abnormality of the biological tissue,
The infrared spectrum information is infrared spectrum information in a wavelength range of 1220 to 1380 nm (excluding 1255-1285 nm),
The computing means identifies normal / abnormality of the living tissue based on a statistic representing a change in infrared spectrum information in the wavelength direction in all or part of the wavelength range.
A biological tissue identification device. The statistic representing the change is an absolute value of the difference in the infrared spectrum information in the wavelength direction.
The biological tissue identification device according to claim 1. The statistic representing the change is a sum of squares of differences of infrared spectrum information in the wavelength direction.
The biological tissue identification device according to claim 1. The infrared spectrum acquisition means acquires infrared spectrum information of the living tissue in the living body with an endoscope.
The biological tissue identification device according to any one of claims 1 to 3. In the calculation means, the biological tissue identified as abnormal is a digestive system tumor,
The biological tissue identification device according to any one of claims 1 to 3. A biological tissue identification method for identifying normality / abnormality of the biological tissue based on infrared spectral information in the wavelength range of 1220 to 1380 nm (excluding 1255-1285 nm) from the biological tissue obtained by the infrared spectrum acquisition means Because
Calculating a statistic representing a change in infrared spectral information in the wavelength direction in all or part of the wavelength range of the infrared spectral information;
Identifying normality / abnormality of the biological tissue based on a statistic representing the change in the infrared spectrum information;
A biological tissue identification method comprising: