JP2011078448A - Optical tomography apparatus and analysis method by optical tomography apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain information on a cross-section of a subject to be measured with a higher degree of accuracy. <P>SOLUTION: In an optical tomography apparatus 1, an MR information acquisition part 10 acquires MR information showing an internal structure of the subject to be measured based on an MR image in which an error occurring in MR imaging is corrected, and an analysis part 40 analyzes a distribution of a scattering coefficient or an absorption coefficient of the inside of the subject to be measured based the MR information. In the analysis by the analysis part 40, a calculation value is calculated by applying the scattering coefficient and the absorption coefficient included in a range defined by a maximum value and a minimum value of the scattering coefficient and the absorption coefficient of each region housed in a housing part 30 to a transport equation being a governing equation, and the calculation value is compared with a measurement value by a measuring part 20 by a comparison part 42. Then, the correction of the scattering coefficient or the absorption coefficient by a correction part 43 and the calculation of the calculation value by a calculation value calculating part 41 are repeated until the result which is a difference between the calculation value and the measurement value is less than a prescribed threshold value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical tomography apparatus and an analysis method using the optical tomography apparatus.

  As a method for obtaining tomographic information of a living body, diffused light tomography using near infrared light that is safe and highly transmissive to the living body is known. Near-infrared light used in this diffuse optical tomography, unlike X-rays, has very low invasiveness to the living body, and substances in the living body have a greater spectral characteristic in the frequency band of near-infrared light depending on the substance. Since they are different, there are advantages such as being able to collect various metabolic information of biological substances such as oxygen with high time resolution. In addition, the measuring device using this diffused optical tomography is small and inexpensive, and the measuring subject is not required to maintain the posture at the time of measurement. Various studies have been conducted with the expectation that it will be applied to more detailed analysis of biological functions. Analysis to obtain tomographic information of living bodies from the results obtained by irradiating a measurement object with near-infrared light Methods and the like have been studied (for example, see Patent Document 1).

Special table 2003-528291 gazette

  However, since near-infrared light is highly absorbed and scattered in the living body, the light that has entered the living body is diffused before being emitted from the living body, and is emitted from the living body that is the measurement object. Because there is little spatial information obtained from the result of receiving the received light, for analysis to calculate parameters in the governing equation (scattering coefficient, absorption coefficient, etc.) of each part in the living body from the result of receiving near-infrared light It may take a long time and the accuracy of the analysis result may be low.

  The present invention has been made in view of the above, and an object thereof is to provide an optical tomography apparatus that can obtain tomographic information of a measurement object with higher accuracy and an analysis method using the optical tomography apparatus.

  In order to achieve the above object, an optical tomography apparatus according to the present invention is an optical tomography apparatus that analyzes the distribution of scattering coefficients or absorption coefficients inside a measurement object, and each of the parts inside the measurement object. MR information for acquiring MR information indicating the internal structure of the measurement object based on an MR image obtained by correcting errors generated during imaging, and a storage unit that stores the maximum and minimum values of the scattering coefficient and the absorption coefficient for each part. Light is incident on the acquisition unit and the measurement target, and the measurement value of the light from the measurement target is acquired by receiving the light emitted from the measurement target as the light is incident. Based on the measurement unit, the measurement value acquired by the measurement unit, the MR information acquired by the MR information acquisition unit, and the scattering coefficient and the absorption coefficient of each part inside the measurement object stored in the storage unit , Scattering unit inside the measurement object Or an analysis unit that analyzes the distribution of the absorption coefficient, and the analysis unit has a structure inside the measurement target specified by the MR information and scattering of each part inside the measurement target stored in the storage unit. By using the scattering coefficient and the absorption coefficient of each part included in the range defined by the maximum value and the minimum value of the coefficient and the absorption coefficient, respectively, in the governing equations governing the light propagation in the measurement object, Obtained by a calculation value calculation unit that calculates a calculation value for information relating to light emitted from the measurement target when light is incident on the measurement target, a calculation value calculated by the calculation value calculation unit, and a measurement unit A comparison unit that compares the measured values with each other and determines whether or not the difference between the calculated value and the measured value is greater than a predetermined threshold value, and the difference between the calculated value and the measured value by the comparing unit is greater than the predetermined threshold value. Is also determined to be large, A correction unit that corrects one or more of the scattering coefficient and the absorption coefficient of each component used in the calculation value calculation unit, and the difference between the calculated value and the measurement value is equal to or less than a predetermined threshold in the comparison unit Until the determination is made, the calculation value calculation unit, the comparison unit, and the correction unit repeat the analysis of the scattering coefficient or absorption coefficient distribution inside the measurement object.

  According to the optical tomography apparatus described above, MR information indicating the internal structure of the measurement object is acquired based on an MR image in which an error generated during imaging is corrected by the MR information acquisition unit, and the MR unit acquires the MR information. Based on the above, the distribution of the scattering coefficient or the absorption coefficient inside the measurement object is analyzed. In the analysis by the analysis unit, the scattering coefficient and the absorption coefficient included in the range defined by the maximum and minimum values of the scattering coefficient and the absorption coefficient of each part stored in the storage unit are applied to the governing equation. The calculated value is calculated, and this is compared with the measured value by the measuring unit. The scattering coefficient or the absorption coefficient is corrected until the result becomes smaller than a predetermined threshold value, and the calculation of the calculated value is repeated. As described above, since the scattering coefficient and the absorption coefficient are calculated using the highly accurate MR information in which the error generated at the time of imaging is corrected, the tomographic information of the measurement object can be obtained with higher accuracy. Further, since the scattering coefficient and the absorption coefficient are calculated using the MR information in which the internal structure of the measurement object is specified, the scattering coefficient and the absorption coefficient can be calculated at higher speed.

  Further, the analysis method by the optical tomography apparatus according to the present invention is an analysis method by the optical tomography apparatus that analyzes the distribution of the scattering coefficient or absorption coefficient inside the measurement object, and each part inside the measurement object. A storage step for storing the maximum and minimum values of the scattering coefficient and absorption coefficient for each part in the storage unit, and MR information indicating the internal structure of the measurement object based on an MR image in which an error generated during imaging is corrected MR information acquisition step to be acquired, and measurement of light from the measurement object by receiving light incident on the measurement object and receiving light emitted from the measurement object as the light is incident A measurement step for acquiring a value; a measurement value acquired in the measurement step; an MR information acquired in the MR information acquisition step; and a measurement object stored in the storage step. An analysis step for analyzing the distribution of the scattering coefficient or the absorption coefficient inside the measurement object based on the scattering coefficient and the absorption coefficient of each part of the part, and the analysis step is a measurement object specified by the MR information The scattering coefficient and the absorption coefficient of each part included in the range defined by the maximum value and the minimum value of the scattering coefficient and the absorption coefficient of each part inside the measurement object stored in the storage unit. Are used in the governing equation that governs the light propagation in the measurement object, so that when light is incident on the measurement object in the measurement step, the calculated value for the information related to the light emitted from the measurement object is calculated. The calculated value calculation step, the calculated value calculated in the calculated value calculation step, and the measured value acquired in the measuring step are compared. And a comparison step for determining whether the difference between the calculated value and the measured value is larger than a predetermined threshold value. A correction step for correcting one or more coefficients among the coefficients, and until the difference between the calculated value and the measured value is determined to be equal to or less than a predetermined threshold in the comparing step, the calculated value calculating step, the comparing step, And the analysis of the distribution of the scattering coefficient or the absorption coefficient inside the measurement object by the correction step is repeated.

  According to the analysis method using the optical tomography apparatus described above, MR information indicating the internal structure of the measurement object is acquired based on the MR image in which an error generated during imaging is corrected in the MR information acquisition step, and the analysis step The distribution of the scattering coefficient or the absorption coefficient inside the measurement object is analyzed based on the MR information. In the analysis in this analysis step, the scattering coefficient and the absorption coefficient included in the range defined by the maximum and minimum values of the scattering coefficient and the absorption coefficient of each part stored in the storage unit are applied to the governing equation. Then, the calculated value is calculated, and this is compared with the measured value by the measuring unit, the scattering coefficient or the absorption coefficient is corrected until the result becomes smaller than a predetermined threshold value, and the calculation of the calculated value is repeated. As described above, since the scattering coefficient and the absorption coefficient are calculated using the highly accurate MR information in which the error generated at the time of imaging is corrected, the tomographic information of the measurement object can be obtained with higher accuracy. Further, since the scattering coefficient and the absorption coefficient are calculated using the MR information in which the internal structure of the measurement object is specified, the scattering coefficient and the absorption coefficient can be calculated at higher speed.

  Here, the governing equation used in the optical tomography apparatus described above can be an aspect that is a transport equation. The governing equation may be a diffusion equation.

  In the analysis method according to the present invention, the governing equation may be a transport equation, and the governing equation may be a diffusion equation.

  Thus, it becomes possible to analyze the fault information with higher accuracy by using the transport equation and the diffusion equation as the governing equations.

  ADVANTAGE OF THE INVENTION According to this invention, the optical tomography apparatus which can obtain the tomographic information of a measurement object with higher precision, and the analysis method by this optical tomography apparatus are provided.

It is a figure explaining the structure of the optical tomography apparatus which concerns on this embodiment. It is a figure explaining the measurement part of an optical tomography apparatus. It is a figure which shows the example of the information stored in a storage part. It is a figure explaining the structure of MR imaging apparatus which images the MR image used for MR information acquired with an optical tomography apparatus. It is a sequence diagram explaining the analysis method by an optical tomography apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a diagram illustrating a configuration of an optical tomography apparatus according to the present embodiment. The optical tomography apparatus 1 irradiates the measurement object with near infrared light, and as a result, receives and analyzes the light emitted from the measurement object. Based on the analysis result, the optical tomography apparatus 1 It has a function to construct and output a tomographic image. As shown in FIG. 1, the optical tomography apparatus 1 according to the present embodiment includes an MR information acquisition unit 10, a measurement unit 20, a storage unit 30, an analysis unit 40, and an output unit 50.

  The MR information acquisition unit 10 acquires MR information indicating the internal structure of the measurement object based on an MR image in which an error that occurs during imaging is corrected. Specifically, an MR image (three-dimensional MR image) is picked up, and the MR image is corrected, and an internal structure of the measurement target is specified based on the corrected MR image. MR information (three-dimensional structure information) in which the structure is specified is acquired. The measurement object to be measured by the optical tomography apparatus 1 according to the present embodiment is, for example, the head of a living body, and when the head of the living body is the measurement object, the inside of the measurement object is used as MR information. Information for identifying the internal structure of the head of is obtained. When the object to be measured is a living body head, MR information includes information specifying the appearance of the head, epidermis, skull, cerebrospinal fluid, brain parenchyma (grey matter, white matter), blood vessel structure (arteries, And information specifying the spatial distribution of the internal tissue of the head, such as a vein). Further, when acquiring MR information, an MR image in which distortion and signal unevenness during imaging are corrected is used. Examples of the MR image to be used include a three-dimensional T1-weighted image, an MR angiographic image, a magnetic susceptibility-weighted image, and a balanced-SSFP (Steady-State Free Precession) image. The correction of MR image distortion and signal unevenness will be described later. The MR information acquired by the MR information acquisition unit 10 is sent to the analysis unit 40.

  The measurement unit 20 receives light with respect to the measurement object and receives light emitted from the measurement object with the incidence of the light, thereby obtaining a measurement value for the light from the measurement object. To do. An example of the configuration of the measurement unit 20 is shown in FIG. FIG. 2A is a diagram illustrating the configuration of the module 20A included in the measurement unit 20, and FIG. 2B is a diagram illustrating the measurement unit 20 including a plurality of modules 20A. As shown in FIG. 2, the measurement unit 20 is formed by connecting a plurality of modules 20 </ b> A including an optical fiber 22, an optical fiber head 21, and an RF receiving coil 105.

  As shown in FIG. 2A, the optical fiber 22 and the optical fiber head 21 are optically connected in one module 20A. The optical fiber head 21 emits the light emitted from the light source and propagated through the optical fiber 22 to the measurement object, or is emitted from the emission end 21A to irradiate the measurement object with light. Thus, it has a function as one of the incident ends 21B for receiving the light emitted from the measurement object. When the optical fiber head 21 functions as the incident end 21B, the optical fiber 22 is optically connected to the light receiving unit, and light incident on the optical fiber 22 from the incident end 21B propagates through the optical fiber 22 and is received. The light is received by the unit. The light emitted from the emission end 21A of the optical fiber head 21 to the measurement object is pulsed light in the near infrared region. An RF receiving coil 105 is further attached to each module 20A. The RF receiving coil 105 is a coil used for MR imaging described later. In the module 20A shown in the present embodiment, the MR information and light obtained by the RF receiving coil 105 are integrated by integrating the RF receiving coil 105 used for MR imaging and the optical fiber head 21 used for optical tomography measurement. The correspondence relationship with the optical tomography measurement result obtained by the fiber head 21 becomes clear. MR imaging using the RF receiving coil 105 will be described later.

As shown in FIG. 2 (B), the measuring unit 20 includes n modules 20A _{1 to} 20A _n connected so that _n optical fiber heads 21 _{1 to} 21 _n are arranged in parallel. . In FIG. 2B, the n modules 20A include an output end 21A from which the optical fiber head 21 emits light to the measurement target, and an input end 21B that receives light from the measurement target. Are connected so as to be alternately arranged. Sectional thus corresponding to a particular section (slice to be acquired in a tomographic image image series like n modules 20A ₁ which is connected to through 20a _n is n light fiber head 21 ₁ through 21 _n is the measurement object ).

In this way, the n modules 20A _{1 to} 20A _n are attached to the measurement object, and light emitted from the measurement object is received by irradiating the measurement object with near-infrared light. Measurement results such as measured values of the received light are sent from the measurement unit 20 to the analysis unit 40. Then, by analyzing the measurement result by the analysis unit 40, the distribution of the absorption coefficient and the scattering coefficient inside the measurement object is obtained.

  The storage unit 30 stores the maximum value and the minimum value of the scattering coefficient and the absorption coefficient of each part inside the measurement object for each part. An example of information stored in the storage unit 30 is shown in FIG. As shown in FIG. 3, in the storage unit 30, an internal tissue (part) that may be included in the measurement object (in FIG. 3, epidermis, skull, cerebrospinal fluid,...) And this part can be taken. The maximum value and the minimum value for defining the range of the scattering coefficient and the absorption coefficient are stored for each part. For example, when the measurement object is the head of a living body, each tissue such as epidermis, skull, cerebrospinal fluid, brain parenchyma (gray matter, white matter), blood vessel structure (arteries, veins), etc. may be included inside Therefore, these tissues and the maximum and minimum values of the scattering coefficient and the absorption coefficient of each tissue are stored in association with the tissues. Information stored in the storage unit 30 is appropriately provided to the analysis unit 40 in response to a request from the analysis unit 40.

  The analysis unit 40 includes the measurement value obtained by the measurement unit 20, the MR information obtained by the MR information acquisition unit 10, and the scattering coefficient and the absorption coefficient of each part inside the measurement object stored in the storage unit 30. Based on the above, the distribution of the scattering coefficient or absorption coefficient inside the measurement object is analyzed. The analysis unit 40 includes a calculated value calculation unit 41, a comparison unit 42, and a correction unit 43.

  The calculated value calculation unit 41 is based on the internal structure of the measurement object specified by the MR information, and the maximum and minimum values of the scattering coefficient and the absorption coefficient of each part inside the measurement object stored in the storage unit 30, respectively. When light is incident on the measurement object by the measurement unit 20 by using the scattering coefficient and the absorption coefficient of each part included in the specified range in the governing equation that governs the light propagation in the measurement object. A calculated value for information relating to light emitted from the measurement object is calculated. The MR information used by the calculated value calculation unit 41 is acquired by the MR information acquisition unit 10 and is an error corrected at the time of imaging. The correction of the error that occurs during imaging will be described later. The calculated value calculated by the calculated value calculation unit 41 is sent to the comparison unit 42.

  The comparing unit 42 compares the calculated value calculated by the calculated value calculating unit 41 with the measured value acquired by the measuring unit 20, and determines whether or not the difference between the calculated value and the measured value is greater than a predetermined threshold value. Judging. As a result of the comparison by the comparison unit 42, when it is determined that the difference between the calculated value and the measurement value is larger than a predetermined threshold value, this result is sent to the correction unit 43.

  When the comparison unit 42 determines that the difference between the calculated value and the measured value is larger than a predetermined threshold, the correction unit 43 is one or more of the scattering coefficient and the absorption coefficient of each component used in the calculated value calculation unit 41. Correct the coefficient. The analysis method by the calculated value calculation unit 41, the comparison unit 42, and the correction unit 43 will be described later.

  And the output part 50 outputs the analysis result by the analysis part 40 outside. Examples of the method for outputting the analysis result to the outside include a method for displaying on a display device such as a monitor, a method for outputting to a printer, a method for outputting as electronic data, and the like.

  Here, the MR imaging apparatus that generates the MR information acquired by the MR information acquisition unit 10 and the MR information will be described. FIG. 4 is a diagram for explaining the configuration of the MR imaging apparatus 100. As shown in FIG. 4, the MR imaging apparatus 100 includes a static magnetic field magnet unit 102, a gradient magnetic field coil unit 103, an RF irradiation coil 104, an RF receiving coil 105, an RF driving unit 111, a gradient driving unit 112, a data collecting unit 113, A control unit 114, a data processing unit 115, an operation unit 116, and a display unit 117 are included.

  When the measurement target of the subject 200 that is the measurement target is the head of a living body, the measurement target is disposed substantially at the center of the static magnetic field magnet unit 102 that generates a uniform static magnetic field of 0.5 T, for example. Yes. The bed 110 is movable in order to place the measurement site of the measurement object at substantially the center of the static magnetic field magnet unit 102. Inside the static magnetic field magnet unit 102 are three axes (X, Y, and Z axes orthogonal to each other. The Z axis coincides with the direction of the static magnetic field generated by the static magnetic field magnet unit 102. These three axes are shown in the figure. A gradient magnetic field coil 103 that generates a maximum gradient magnetic field, for example, 10 mT / m in the direction of (not), and this gradient magnetic field coil 103 is applied to a measurement object in the static magnetic field formed by the static magnetic field magnet unit 102. Apply a gradient magnetic field. By applying the gradient magnetic field, position information is added to the MR signal received by the RF receiving coil 105.

  Inside the gradient magnetic field coil 103, an excitation radio frequency (RF) irradiation coil 104 that generates a high frequency magnetic field for exciting spins of protons in the imaging region 101 and a magnetic field generated by the RF irradiation coil 104 are excited. A receiving RF coil 105 for detecting MR signals from the protons is incorporated. Note that the RF receiving coil 105 of the present embodiment is formed separately from the RF irradiation coil 104, and as shown in FIG. 2, the optical fiber head 21 and the optical fiber 22 that constitute the measuring unit 20 of the optical tomography apparatus 1 Although integrated and configured to function as the measurement unit 20 of the optical tomography apparatus 1, the RF irradiation coil 104 and the RF reception coil 105 may share one RF coil. The high frequency magnetic field constituted by the RF irradiation coil 104 is controlled by the RF drive unit 111. In addition, the gradient magnetic field configured by the gradient magnetic field coil 103 is controlled by the gradient magnetic field driving unit 112.

  The data collection unit 113 collects MR signals received by the RF reception coil 105 based on the control signal from the control unit 114. Then, the MR signal collected by the data collecting unit 113 is sent to the data processing unit 115. The RF drive unit 111, the gradient magnetic field drive unit 112, and the data collection unit 113 perform the above operation based on the control signal from the control unit 114.

  The data processing unit 115 outputs an operation instruction from the operation unit 116 by the operator to the control unit 114, acquires the MR signal collected in the data collection unit 113 based on the operation instruction, and acquires the acquired MR signal. It has a function of generating image data by performing image reconstruction processing on the MR signal. The output unit 117 displays the image data generated by the data processing unit 115 on a display device and the like, and the data used for the image processing is displayed on an external device (for example, the optical tomography device 1 of the present embodiment). ).

  Here, data processing by the data processing unit 115 will be described. In the data processing unit 115, correction is performed when an MR image is generated from the MR signal received by the RF receiving coil 105 of the MR imaging apparatus 100. It is known that various errors occur when the MR imaging apparatus 100 performs MR imaging of an object to be measured. For example, spatial distortion occurs due to non-uniformity of the static magnetic field formed by the static magnetic field magnet unit 102 and non-linearity of the gradient magnetic field formed by the gradient magnetic field coil 103. In addition, a phased array coil that is generally used as an RF receiving coil 105 in recent years for the purpose of improving the signal-to-noise ratio and speeding up imaging has a spatially non-uniform sensitivity distribution. Spatial unevenness also occurs on the obtained MR image. In this manner, since the MR imaging apparatus 100 captures images including various distortions and errors, the data processing unit 115 corrects the MR image.

  Specifically, the MR imaging device 100 is used to image a phantom in advance, thereby measuring the distortion derived from the gradient magnetic field coil 103 and the signal non-uniformity derived from the RF receiving coil 105 that are generated during imaging, and the measurement object. For example, there is a method of correcting the image pickup result to cancel distortion and signal non-uniformity generated at the time of phantom image pickup. As described above, the data processing unit 115 corrects an error generated in the MR imaging apparatus 100, and information on the internal structure of the measurement target obtained from the corrected MR image is output as MR information from the output unit 117 to the optical tomograph. The MR information acquisition unit 10 of the optical tomography apparatus 1 acquires MR information based on an MR image in which an error that occurs during imaging is corrected by transmitting the information to the lithography apparatus 1.

  Next, an analysis method using the optical tomography apparatus 1 will be described with reference to FIG. FIG. 5 is a sequence diagram illustrating an analysis method using the optical tomography apparatus. First, as a premise for performing measurement of the measurement object by the optical tomography apparatus 1 and analysis of the measurement result, the storage unit 30 includes a scattering coefficient and an absorption coefficient for each part included in the measurement object. A table in which the maximum value and the minimum value are associated with each other is stored (S01, storage step). Information regarding the maximum and minimum values of the scattering coefficient and the absorption coefficient for each part may be stored in the storage unit 30 every time the measurement object changes, or may be measured in advance. It is good also as an aspect which stores all the information about a target object in the storage part 30. FIG.

  Next, MR information is acquired by the MR information acquisition unit 10 of the optical tomography apparatus 1 (S02, MR information acquisition step). The MR information acquired by the MR information acquisition unit 10 is sent to the analysis unit 20. Here, the information sent to the analysis unit 20 includes information specifying the external shape of the measurement object and specifying the internal tissue interface (that is, information specifying the internal structure). Next, the calculated value calculation unit 41 of the analysis unit 40 refers to the MR information and is a coefficient used in the simulation of light propagation using the transport equation at the later stage, and corresponds to each part inside the measurement object. Information relating to the scattering coefficient and absorption coefficient of the obtained tissue is acquired from the storage unit 30 (S03, coefficient initialization). Here, the scattering coefficient and the absorption coefficient acquired from the storage unit 30 can be determined in advance, for example, as a center value in a range defined by the maximum value and the minimum value.

  Next, in the measurement part 20, the optical tomography measurement with respect to a measurement object is performed (S04, measurement step). Here, a plurality of modules 20A shown in FIG. 2B are attached to the measurement object, and the measurement object is irradiated with light from the emission end 21A of the optical fiber head 21, and the measurement object is irradiated by this light irradiation. Measurement is performed by receiving light emitted from the object at the incident end 21B. The measurement result by the measurement unit 20 is sent from the measurement unit 20 to the analysis unit 40.

  Next, the calculated value calculation unit 41 of the analysis unit 40 performs a simulation of light propagation in the measurement object. Specifically, by applying the scattering coefficient and the absorption coefficient acquired from the storage unit 30 to the transport equation. A calculated value is calculated (S05, calculated value calculating step). Here, when applying the scattering coefficient and the absorption coefficient of the tissue constituting the inside of the measurement object to the transport equation, the measurement is performed based on the information specifying the internal structure of the measurement object included in the MR information. A scattering coefficient and an absorption coefficient corresponding to each part of the object are applied to the transport equation. The calculated value calculated by the calculated value calculation unit 41 is sent to the comparison unit 42 of the analysis unit 40.

  Next, the comparison unit 42 of the analysis unit 40 compares the calculation value calculated by the calculation value calculation unit 41 with the measurement value obtained by the measurement unit 20 (S06, comparison step). Then, the comparison unit 42 determines whether or not the difference between the calculated value and the measured value is equal to or less than a predetermined threshold (S07, comparison step).

  Here, when measuring the measurement object by the measurement unit 20 of the optical tomography apparatus 1, the propagation of the light incident on the measurement object will be described, and the measurement result analysis by the analysis unit 40 of the optical tomography apparatus 1 will be described. Will be described. It is known that the propagation of light in a measurement object when light is incident on the measurement object is governed by an equation describing particle motion called a transport equation. By using this transport equation, it is possible to accurately model the relationship between the light incident into the measurement object and the light emitted from the measurement object due to the incidence of this light. Therefore, by applying the correct values of the scattering coefficient and the absorption coefficient corresponding to the tissue of each part to this transport equation, when specific light is incident on the measurement object, it is emitted from the measurement object. It should be possible to accurately calculate the emitted light.

  However, the distribution of the scattering coefficient and the absorption coefficient at each part in the measurement object cannot be accurately grasped in advance. Therefore, a value selected from the range of the scattering coefficient and the absorption coefficient for each part stored in the storage unit 30 is applied to the transport equation, and the result (calculated value) and the actual value (measured value) by the measuring unit 20 are applied. Is compared in the comparison unit 42 to confirm whether the scattering coefficient and absorption coefficient assigned to the transport equation are close to or greatly different from the scattering coefficient and absorption coefficient of each part in the measurement object. can do. At this time, when the threshold value is determined in advance in the comparison unit 42 and the difference between the calculated value and the measured value is equal to or smaller than the threshold value, the scattering coefficient and the absorption coefficient of each part assigned to the transport equation are close to the actual values. The scattering coefficient and the absorption coefficient of each part used for calculation of this calculated value are determined to be analysis results.

  Therefore, when the comparison unit 42 determines that the difference between the calculated value and the measured value is less than or equal to the threshold value, the result is sent from the comparison unit 42 to the output unit 50, and the output unit 50 calculates the calculated value. A tomographic image of the measurement object is formed and output using the analysis result using the scattering coefficient and the absorption coefficient used for the calculation (S08).

  On the other hand, when the comparison unit 42 determines that the difference between the calculated value and the measurement value is not less than or equal to the threshold (that is, greater than the threshold), the result is sent from the comparison unit 42 to the correction unit 43. The correction unit 43 corrects at least one of the scattering coefficient and the absorption coefficient (S09, correction step). Here, the values of the scattering coefficient and the absorption coefficient applied to the transport equation are corrected so that the difference between the calculated value and the measured value becomes smaller. Then, the scattering coefficient and the absorption coefficient corrected by the correcting unit 43 are sent to the calculated value calculating unit 41, and the calculated value is calculated a second time using the corrected value in the calculated value calculating unit 41. (S05) The comparison between the second calculation value and the measurement value obtained as a result is performed in the comparison unit 42 (S06, S07), and the comparison result (difference between the calculation value and the measurement value) is based on the threshold value. If also larger, the coefficient is corrected again (S09). As described above, calculation of the calculated value, comparison between the calculated value and the measured value, and correction of the coefficients (S05 to S07, S09) are repeatedly performed until the difference between the calculated value and the measured value becomes smaller than a predetermined threshold value. When the difference between the calculated value and the measured value is less than or equal to the threshold value, the tomographic information formed using the result is output from the output unit 50 (S08), thereby performing a series of processes related to the analysis. Is terminated.

  As described above, according to the optical tomography apparatus 1 or the analysis method using the optical tomography apparatus 1 according to the present embodiment, the measurement target based on the MR image in which the error generated during MR imaging is corrected by the MR information acquisition unit 10. MR information indicating the internal structure of the object is acquired, and the analysis unit 40 analyzes the distribution of the scattering coefficient or absorption coefficient inside the measurement object based on the MR information. In the analysis by the analyzing unit 40, the scattering coefficient and the absorption coefficient included in the range defined by the maximum value and the minimum value of the scattering coefficient and the absorption coefficient of each part stored in the storage unit 30 are the governing equations. The calculated value is calculated by applying to the equation, and this is compared with the measured value by the measuring unit 20 in the comparing unit 42, and the scattering coefficient or the absorption coefficient is changed by the correcting unit 43 until the result becomes smaller than a predetermined threshold value. The calculation value calculation unit 41 repeats the calculation of the calculation value. As described above, since the optical tomography apparatus 1 calculates the scattering coefficient and the absorption coefficient using the highly accurate MR information in which the error generated during imaging is corrected, the tomographic information of the measurement target can be obtained with higher accuracy. Can be sought. In the analysis by the optical tomography apparatus 1 described above, the scattering used for the calculated value from the range of the scattering coefficient and the absorption coefficient stored in the storage unit 30 based on the MR information in which the internal structure of the measurement object is specified. Since the calculation value is calculated by selecting the coefficient and the absorption coefficient, the processing related to the calculation of the scattering coefficient and the absorption coefficient can be performed in a short time.

  In the above embodiment, the governing equation governing the scattering and absorption of light inside the measurement object is the transport equation, and the calculated value calculation unit 41 of the optical tomography apparatus 1 scatters the transport equation. Although the aspect which calculates a calculated value by applying a coefficient and an absorption coefficient was demonstrated, a diffusion equation can also be used as a governing equation. The diffusion equation is a simplification of the transport equation by assuming that light scattering in the medium is perfectly isotropic. When this diffusion equation is used as the governing equation, it is easier to handle compared to the transport equation, so calculation values and correction of coefficients based on the calculation results are facilitated, and analysis related to fault information of the measurement object Can be performed with a smaller number of trials.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, A various change can be made.

  For example, in the above embodiment, a part of the measurement mechanism of the optical tomography apparatus 1 (the optical fiber head 22 and the optical fiber 21) and a part of the measurement mechanism of the MR imaging apparatus 100 (RF reception coil 105) are integrated as a module 20A. However, the optical tomography apparatus 1 and the MR imaging apparatus 100 may be different from each other, or the optical tomography apparatus 1 and the MR imaging apparatus 100 are integrated with each other. Also good.

DESCRIPTION OF SYMBOLS 1 ... Optical tomography apparatus, 10 ... MR information acquisition part, 20 ... Measurement part, 21 ... Optical fiber head, 22 ... Optical fiber, 30 ... Storage part, 40 ... Analysis part, 41 ... Calculation value calculation part, 42 ... Comparison Part, 43 ... correction part, 50 ... output part, 100 ... MR imaging device.

Claims (6)

An optical tomography apparatus for analyzing the distribution of scattering coefficient or absorption coefficient inside a measurement object,
A storage unit that stores the maximum value and the minimum value of the scattering coefficient and the absorption coefficient of each part inside the measurement object;
An MR information acquisition unit that acquires MR information indicating an internal structure of the measurement object based on an MR image in which an error that occurs during imaging is corrected;
A measurement unit that obtains a measurement value of light from the measurement object by receiving light incident on the measurement object and receiving light emitted from the measurement object with the incidence of the light; ,
The measurement value acquired by the measurement unit, the MR information acquired by the MR information acquisition unit, and the scattering coefficient and the absorption coefficient of each part inside the measurement object stored in the storage unit Based on the analysis unit for analyzing the distribution of the scattering coefficient or absorption coefficient inside the measurement object,
With
The analysis unit
It is defined by the internal structure of the measurement object specified by the MR information and the maximum and minimum values of the scattering coefficient and absorption coefficient of each part inside the measurement object stored in the storage unit. The scattering coefficient and the absorption coefficient of each part included in the range are used in a governing equation that governs light propagation in the measurement object, so that when the light is incident on the measurement object by the measurement unit, A calculated value calculation unit for calculating a calculated value for information relating to light emitted from the measurement object;
The calculated value calculated by the calculated value calculating unit is compared with the measured value acquired by the measuring unit, and it is determined whether or not the difference between the calculated value and the measured value is larger than a predetermined threshold value. A comparison unit to
When the comparison unit determines that the difference between the calculated value and the measured value is larger than a predetermined threshold, one or more coefficients of the scattering coefficient and the absorption coefficient of each component used in the calculated value calculation unit are A correction part to be corrected;
Have
Until the difference between the calculated value and the measured value is determined to be less than or equal to a predetermined threshold value in the comparing unit, scattering inside the measurement object by the calculated value calculating unit, the comparing unit, and the correcting unit An optical tomography apparatus that repeats analysis of a coefficient or an absorption coefficient distribution.   The optical tomography apparatus according to claim 1, wherein the governing equation is a transport equation.   The optical tomography apparatus according to claim 1, wherein the governing equation is a diffusion equation. An analysis method using an optical tomography device that analyzes the distribution of scattering coefficients or absorption coefficients inside a measurement object,
A storage step of storing the maximum value and the minimum value of the scattering coefficient and the absorption coefficient of each part inside the measurement object in a storage unit for each part;
MR information acquisition step for acquiring MR information indicating an internal structure of the measurement object based on an MR image in which an error occurring during imaging is corrected;
A measurement step of obtaining a measurement value of light from the measurement object by receiving light incident on the measurement object and receiving light emitted from the measurement object with the incidence of the light; ,
The measurement value acquired in the measurement step, the MR information acquired in the MR information acquisition step, and the scattering coefficient and the absorption coefficient of each part inside the measurement object stored in the storage step. Based on the analysis step of analyzing the distribution of the scattering coefficient or absorption coefficient inside the measurement object,
With
The analysis step includes
It is defined by the internal structure of the measurement object specified by the MR information and the maximum and minimum values of the scattering coefficient and absorption coefficient of each part inside the measurement object stored in the storage unit. The scattering coefficient and the absorption coefficient of each part included in the range are used in the governing equation that governs the light propagation in the measurement object, so that the light is incident on the measurement object in the measurement step. A calculated value calculating step for calculating a calculated value for information relating to light emitted from the measurement object;
The calculated value calculated in the calculated value calculating step is compared with the measured value acquired in the measuring step, and it is determined whether or not the difference between the calculated value and the measured value is larger than a predetermined threshold value. A comparison step to
When it is determined in the comparison step that the difference between the calculated value and the measured value is greater than a predetermined threshold, one or more coefficients of the scattering coefficient and the absorption coefficient of each component used in the calculated value calculating step are determined. Correction steps to correct;
Have
Until the difference between the calculated value and the measured value is determined to be equal to or less than a predetermined threshold in the comparing step, the scattering inside the measurement object by the calculated value calculating step, the comparing step, and the correcting step. An analysis method characterized by repeating the analysis of the coefficient or absorption coefficient distribution.   The analysis method according to claim 4, wherein the governing equation is a transport equation. The analysis method according to claim 4, wherein the governing equation is a diffusion equation.

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