Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
  • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
  • G01N21/64—Fluorescence; Phosphorescence
  • G01N21/645—Specially adapted constructive features of fluorimeters
  • G01N21/6456—Spatial resolved fluorescence measurements; Imaging
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
  • A61B5/0071—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence by measuring fluorescence emission
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
  • A61B5/0082—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes
  • A61B5/0084—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes for introduction into the body, e.g. by catheters
  • A61B5/0086—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes for introduction into the body, e.g. by catheters using infrared radiation
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F18/00—Pattern recognition
  • G06F18/20—Analysing
  • G06F18/21—Design or setup of recognition systems or techniques; Extraction of features in feature space; Blind source separation
  • G06F18/213—Feature extraction, e.g. by transforming the feature space; Summarisation; Mappings, e.g. subspace methods
  • G06F18/2133—Feature extraction, e.g. by transforming the feature space; Summarisation; Mappings, e.g. subspace methods based on naturality criteria, e.g. with non-negative factorisation or negative correlation
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
  • A61B5/0075—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
  • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
  • G01N21/64—Fluorescence; Phosphorescence
  • G01N2021/6417—Spectrofluorimetric devices
  • G01N2021/6423—Spectral mapping, video display
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
  • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
  • G01N21/64—Fluorescence; Phosphorescence
  • G01N21/6428—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes"
  • G01N2021/6439—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" with indicators, stains, dyes, tags, labels, marks

Definitions

• the invention relates to the field of optical imaging applied to the medical field.
• This technique offers the prospect of non-invasive diagnostic systems through the use of non-ionizing, easy-to-use and inexpensive radiation.
• Fluorescent markers are injected into the subject and bind to certain specific molecules, for example cancerous tumors.
• the area of interest is illuminated at the optimal excitation wavelength of the fluorophore (the chemical substance of a molecule capable of emitting fluorescence light after excitation) and the fluorescent signal is detected.
• Optical diffusion imaging - without fluorescent marker injection - is already used in clinical settings, particularly in the areas of mammography and neurology.
• Fluorescence optical imaging (with specific fluorophore injection) is focused on "small animal” applications, due to the lack of suitable markers and injectable to humans, and the problem of tissue autofluorescence. which arises for the detection in depth. Indeed, to apply this method to the diagnosis of cancer in humans, it is essential that the specific signal located deeper under the skin than in the small animal can be detected. But the Specific signal to detect weakens with depth, mainly because of tissue absorption and diffusion, and confronts a parasitic signal that disrupts detection. This signal, called “auto-fluorescence”, describes the fluorescence of tissues to which no specific chemical or fluorophore has been injected: this is the natural fluorescence of the tissue.
• the excitation wavelength is then close to the 400 nm wavelength for which the intensity of the autofluorescence signal is maximum.
• optical fluorescence spectroscopy uses near infrared excitation wavelengths, which provide less absorption, and allows better penetration of tissue. The autofluorescence of tissues is then much weaker and becomes a signal to be suppressed rather than used.
• the invention firstly relates to a method for locating at least one fluorescent marker in a scattering medium, wherein: a) at least one fluorescence image or acquisition or a series or a plurality of images or d fluorescence acquisitions, by excitation of the medium, each image or acquisition possibly comprising, on the one hand, a fluorescence component due to the marker or the markers, on the other hand an autofluorescence component due to a part of the medium other than the markers, the measured data of the image or of the acquisition or images or acquisitions that can be stored in a multidimensional array X, b) the data or table is processed by factoring this table into a product of only two non-negative multidimensional arrays, for example two non-negative matrices (if the spatial dimension is equal to 1), A and S, c) a graphical representation of the distribution of intensity or intensities of one or more sources of fluorescence, possibly of the autofluorescence which can be considered as a source of fluorescence, is determined from the data contained in Tables A
• the invention also relates to a method for processing an image or acquisition or a series of images or fluorescence acquisitions in a scattering medium comprising at least one fluorescent marker, each image or acquisition being obtained by excitation of this medium, this image or acquisition may comprise, on the one hand, at least one fluorescence component due to the marker, and, on the other hand, an autofluorescence component due to a part of the medium other than the markers, a method in which which, during a processing step, these data or a table X of data from the series of images or acquisitions by factorization of this table X are processed into a product of only two non-negative multidimensional arrays, by example two non-negative matrices, A and S.
• a method according to the invention may be preceded by the introduction of at least one marker in the medium.
• the first array of non-negative AS A product is an array whose elements a q, p are weighting coefficients, a q, p being the contribution of the spectrum represented by the pth line of S, at the coordinate point q.
• the second non-negative table S is a matrix whose lines correspond to the emission spectra of the fluorescent sources considered, the number of rows of the table S and the number of columns of the array A corresponding then to the number of fluorescence sources considered.
• Table X is formed by making successive acquisitions, an acquisition being able for example to correspond to a given position of the source and to a given position of the detector. Each of these positions can be modified by a new acquisition.
• the table S is, in general, a matrix, therefore an array of dimension 2, even though A and X may each be of dimension strictly greater than 2.
• A is determined A and S by minimizing a cost or objective function, which function can be or
• At least one row of the table S can be initialized, by a reference spectrum of the corresponding fluorescence source. This reference spectrum can be obtained empirically or from tabulated values. Table X obtained is preferably treated according to an iterative process.
• the arrays Ai + i and Si + i, obtained during the iteration of order 1 + 1 being determined from the arrays Ai and Si obtained during the iteration of order 1.
• the number of iteration can be determined according to the fluctuations of the tables A and S, or automatically, according to fluctuations of the function of cost during 2 or more successive iterations. This number of iterations can also be determined empirically, depending on the experience of the user.
• a and S can be determined by an iterative method comprising, at each iteration, the minimization of a cost function, this cost function comprising:
• the position of one of the sources can be obtained by eliminating contributions from other sources in the Table S, then performing the product of A with the table S thus modified. It is also possible to replace the coefficients of the columns of Table A that do not correspond to the chosen source by a null value. It is still possible to extract the column of A and the line of S corresponding to the desired source and to produce the product of this column and this line.
• the excitation of the medium may be carried out by a laser excitation source, which may possibly be focused at the interface between the scattering medium and the external medium.
• the excitation light will then penetrate into the scattering medium, and excite markers or sources in this medium, for example 3 cm or 5 cm deep, that is to say at a distance from the interface, in the diffusing medium.
• the fluorescence radiation therefore comes from a zone at depth, for example between the interface and about 3 cm or 5 cm away from the interface, or between 1 cm at a distance from the interface and 5 cm at a distance of the interface.
• the excitation may occur in the infra ⁇ red or near infra-red, for example at a wavelength between about 600 and 900 nm. Fluorescence can be detected at wavelengths greater than 700 nm or 750 nm. An excitation at wavelength greater than 750 nm or at 800 nm is also possible, with, for example, a fluorescence at wavelength greater than 800 nm or 900 nm.
• the acquisition can be performed by an image sensor producing an image which gives, for points of the studied area, the spectral distribution of the fluorescence radiation from these points. Each acquisition can be carried out using a detector comprising a line of elementary detectors; the detector line can be moved, a fluorescence acquisition being performed for each position of the detector line.
• the excitation can be performed using a laser, and the excitation line is displaced, a fluorescence image (X) can be made for each position of the excitation line.
• the invention also relates to a device for locating at least one fluorescent marker in a scattering medium, comprising: a) means for producing an excitation beam, and means for focusing this beam, b) means for producing a acquisition or an image or series of acquisitions or fluorescence images of points or sources of the medium, each acquisition may comprise the fluorescence components due to the different fluorescent sources present, for example on the one hand one or more markers and secondly, autofluorescence, c) means for processing a table X of the data obtained by the series of acquisitions by factorization into two non-negative tables A and S, d) means for determining a graphical representation of the distribution of intensities of the different sources of fluorescence, these different sources may be one or more fluorescent markers and one autofluorescence.
• the means for carrying out an acquisition or an image or a series of acquisitions or images preferably comprise an image sensor giving, for points of the zone studied, the spectral distribution of the fluorescence radiation coming from these points. Focusing is preferably at the interface of the medium with the environment.
• the means for producing a laser beam make it possible to produce a zone, called an excitation zone, focused for example at the interface of this medium with the ambient medium.
• the excitation light then enters the medium, diffuses there, and will excite the sources of fluorescence, markers and autofluorescence.
• This excitation zone may be an excitation line.
• the sources of fluorescence can be located in depth, remotely under the interface.
• a device according to the invention may further comprise means for modifying the position of this excitation zone, a fluorescence image being produced for each position of the excitation zone.
• At least part of the means for performing a detection of the fluorescence signal from said medium may be arranged along a line, called the detection line.
• a device according to the invention may further comprise means for change the position of this line along two axes.
• the means for processing the acquisition matrix (or multidimensional array) by factorization into two non-negative arrays A and S implement a method according to the invention, as already described above.
• FIG. 1 represents a device for implementing the invention
• FIG. 2 illustrates how a fluorescence acquisition is constituted
• FIG. 3 represents a fluorescence acquisition obtained, with autofluorecence and fluorescence
• FIGS. 4A and 4B respectively represent schematically a matrix S of spectra, with 2 fluorescent sources and therefore 2 lines, and a product of two arrays, whose matrix S, to obtain array X,
• FIGS. 5A and 5B respectively represent a spectral model of autofluorescence and fluorescence, for initializing an S matrix in a method according to the invention
• FIG. 6 represents autofluorescence and fluorescence spectra detected after treatment according to FIG. invention, and a comparison with initial models
• FIGS. 7A and 7B respectively represent an image of autofluorescence, and a image of the fluorescence, obtained after treatment according to the invention of the image of FIG.
• FIG. 8 represents steps of a method according to the invention
• FIGS. 9, 10A and 10B represent fluorescence images (FIGS. 9 and 10B)
• an image of autofluorescence (FIG. 10A) obtained after processing, according to methods of the prior art, the image of FIG.
• Figure 1 is an example of an experimental system for implementing the invention.
• the illumination of an area of an object is obtained using a continuous laser 2 whose beam, which emits for example a radiation in the infrared or even the near infrared, is focused with focusing means to reach a certain area on the surface of the scattering medium, this area may be a line.
• the excitation light then diffuses into an area of the scattering medium, different from the previous zone and will excite one or more fluorescent species.
• Means 6 make it possible to achieve a spectral dispersion of the fluorescence radiation emitted by the scattering medium studied in the external medium. These means 6 are coupled to means 8, forming an image sensor, to produce an image which gives, for points of the studied area, the spectral distribution of the fluorescence radiation. from these points.
• the image sensor of these means 8 is a linear matrix (N ⁇ , N xd ), where N ⁇ is the number of channels corresponding to the range of wavelength considered, and N xd is the number of pixels corresponding to the number of points detected on the line.
• the means 8 comprise means for digitizing the image.
• Data processing means 24 will make it possible to implement a processing method for analyzing the digital data thus obtained, in particular in terms of the spatial and / or spectral distribution of the fluorescent markers.
• These electronic means 24 comprise for example a microcomputer programmed to store and process the data acquired by the means 8. More precisely, a central unit 26 is programmed to implement a processing method according to the invention.
• Display or display means 27 allow, after treatment, to represent the positioning or the spatial distribution of the fluorophores in the medium under examination.
• the means 24 may optionally control or control other parts of the experimental device.
• the medium studied is a diffusing medium, for example a biological tissue.
• incident radiation can penetrate into the medium, the depth of penetration into the medium of up to a few cm depending on the attenuation coefficient of this medium, for example 3 cm or 5 cm.
• fluorophores located at a distance between 0 cm (so very close to the surface) and 3 cm or 5 cm will be detected.
• the detection means 6, 8 thus detect a radiation which comes from the zone of the scattering medium excited by the laser beam, which passes through the diffusing medium towards the boundary between the scattering medium and the external medium, then which reaches the means 6 detection and spectral dispersion.
• the detection means are not necessarily focused on the zone or the excitation line, but can be shifted and aim for another zone or line, in particular on the surface of the medium. This embodiment is made possible due to the diffusion of light in the medium.
• the medium studied can be a living medium. It may be for example an area of the human or animal body.
• the body envelope constitutes the interface of the diffusing medium with the external medium.
• An excitation source is therefore focused on this interface, for example along a line. Markers injected into this scattering medium make it possible to locate areas such as tumors.
• a laser source having an excitation wavelength equal to 690 nm is focused along a line on the interface and makes it possible to carry out an excitation of the fluorophores in the scattering medium, at a depth that can reach a few centimeters.
• the line can be fixed, and in this case one acquires only one line of the object.
• the source 2 can be coupled to a laser fiber 3.
• a lens 4 makes it possible to focus the beam in the form of a laser line at the interface of the medium studied.
• the laser excitation can be positioned above the object, as in FIG. 1, and it is then possible to make an observation in reflection: the fluorescence signal is detected above the object, or on the same side of the object. the object that the radiation source, by an imaging spectrometer 6 coupled to a CCD camera 8.
• An excitation filter is used, it allows to purify the Laser signal.
• a system 10 allows high-pass filtering, which cuts wavelengths below 700 nm, for example an RG9 filter system. This filtering is positioned in front of the lens, to block the parasitic excitation coming from the laser beam itself.
• the acquired image is then obtained using software from the manufacturer Andor or Labview, and we can control the system and translation plates by a single Labview interface.
• FIG. 1 also shows an axis X d which describes the position of the N x d detectors aligned along a detection line in the means 8.
• the fluorescence along the detection line is detected, and a wavelength spectrum (on the abscissa) of points of the line (ie the points i xd of the axis X d of the ordinates of FIG. 2) is realized .
• (i xs , i ys ) the coordinates of a point source, for example a laser source.
• this source contains N xs (- ⁇ 2) elementary sources according to the line.
• a single fluorescent source is here detected along the line at the position i xd of the source positioning point, in the wavelength range between 850 and 900 nm.
• a first part A which is of the autofluorescence visible all along the acquisition line Xd whose maximum intensity is around 700 nm.
• the second part B is fluorescence due to the fluorophore (ICG - indocyanine green) it is spatially more localized than autofluorescence and its emission spectrum has a peak around 860 nm.
• a fluorescent source may therefore comprise several emission zones, distributed at various positions in the scattering medium.
• Such an image can be processed by a method according to the invention, in particular in order to separate the contribution of the autofluorescence on the one hand and that of the source or sources of fluorescence, on the other hand, the latter coming from fluorophores present in the medium examined.
• non-negative matrix is meant a matrix whose all elements are non-negative.
• P is the number of fluorescence sources considered.
• the matrix X corresponds to the digitized image which has been obtained by the measurement:
• X is the matrix expression of the image.
• the matrix A is called the weighting matrix and an element a lxd , p (> _ 0) of this matrix represents the weight of the source p at position i xd of the measurement line X d .
• It is of size N xd * P, the number of lines N xd representing the number of points selected along the fluorescence line, the number of columns p representing the number of sources likely to be present in the medium: fluorescent markers and possibly autofluorescence.
• S is the matrix of the spectra and s p , l ⁇ ( ⁇
• each line of the matrix S corresponds to the emission spectrum of a fluorescent source, this spectrum being discretized along N ⁇ channels.
• each source except autofluorescence, has a spectrum close to that of a monochromatic source; but in practice there is some dispersion around a central frequency.
• the line p of the matrix S can therefore comprise several non-zero elements.
• FIG. 4A gives the illustrated example of an S matrix for an acquisition with two fluorescent sources considered: the two lines represent the emission spectra of the two sources considered, one of which, the first one, has a spectral distribution more wide than the second.
• N xd points along the line which corresponds to Nxd detectors, so we have:
• FIG. 4B shows the imaged example of the product of a matrix S (for an acquisition with two fluorescent sources) with a table in order to obtain the table XS containing information on the fluorescence spectra, while A defines their weighting. in each of the lines of X.
• the algorithm starts with an initialization of matrices A and S to the desired dimensions, and respecting the constraints of positivity.
• the columns of A are initialized randomly, while the S lines are initialized by reference spectra, representing the estimated emission spectra of the searched fluorescent sources or corresponding to these spectra. These spectra are determined empirically or according to tabulated values.
• the matrices are initialized, but then evolve during the algorithm.
• the minimization of the function Q FMN S e is done in two iterative steps. First, for S fixed, the matrix A is searched. Then, for fixed A, the matrix S is computed. The formulas of update of matrices A and S are then:
• the algorithm implemented in the context of the invention is therefore an iterative algorithm that updates the matrices A and S searched according to the update functions described above which minimize as iterations the function objective (Euclidean distance between X and A. S).
• the number of iteration is determined according to the fluctuations of the matrices A and S, or automatically, according to the fluctuations of the cost function, Q FMN , during 2 or more successive iterations, or empirically.
• the initialization of the algorithm consists in principle in creating two random matrices A and S, and then updating them during iterations.
• At least the first lines, and preferably all the lines (for more robustness), of the matrix S are chosen at initialization, which amounts to giving the approximate shape of the spectra of the corresponding sources.
• approximate spectra one for autofluorescence, the others being those of the fluorescence source (s) due to the marker (s).
• a Only fluorescent marker one chooses two spectral models, one for autofluorescence and one for fluorescence of the marker, as illustrated respectively in FIGS. 5A and 5B, on the basis of a priori knowledge of the autofluorescence and the fluorescence of the fluorescence marker. marker pen .
• the columns of A are initialized randomly, the initialization of the lines of S as previously described proving to be sufficient for the initialization step for a satisfactory final result.
• the matrix A is updated.
• the matrix S is updated.
• the matrix A ' being then the matrix A for which all the coefficients of the columns other than the pth column are set to zero.
• a method according to the invention implements an image processing method which, applied to the image of FIG. 3, leads to the results of FIGS. 5A, 5B, 6, 7A and 7B.
• FIGS. 5A and 5B show the shape of the spectra chosen for the initialization of the two sources, ie the two lines of the initial matrix S.
• FIG. 6 shows the final shape of the spectra of the two main sources detected in solid lines (the initialization spectra are in dotted line), for autofluorescence and fluorescence (ICG).
• FIGS 7A and 7B show the result in images: fluorescence ( Figure 7B) can be separated from autofluorescence ( Figure 7A).
• a step S1 one or more acquisitions are made by excitation of the scattering medium, by laser beam; this results, for example, in one or more images; in a step S2, the matrices A and S are initialized,
• step S 3 it is then possible to carry out a graphical representation of one or more sources of fluorescence, or a visualization of one or more sources (step S4), by selecting the desired source, for example by setting the coefficients of the other sources to zero in the matrix S.
• An image corresponding to the photons produced by one or more fluorescent sources is thus constructed, for example by multiplying respectively the (the) columns of the corresponding matrix A by the line (s) of the matrix S corresponding to the selected source or sources that are searched.
• each detector will have 2 coordinates (i xd , i yd ) along the axes Xd and Yd respectively, with 1 ⁇ i xd ⁇ N xd and 1 ⁇ i yd ⁇ N yd .
• the Laser line is preferably fixed.
• each detector is aligned along the axis Xd and one moves along the axis Yd in order to have a measurement for all the (ixd, iyd) coordinates of detectors,
• the detector line remains preferentially fixed.
• the coordinates of an elementary source are then i xs and i ys .
• the source is linear along an axis Xs and is moved along the axis Ys.
• ixs remains constant and only iys evolves. According to a preferred embodiment of the invention, either the on-line source or the detector is moved.
• the coordinates (ixs, iyd) are not useful. Only the coordinates (ixd, iys, i ⁇ ) are useful so that X (and A) can be considered as (only) three-dimensional arrays.
• the marks Xd, Yd and Xs, Ys can respectively be respectively associated with a reference plane, which can be the work plane on which the object to be analyzed is arranged, or the source displacement plane, or the displacement plane. of the detector.
• An image or table of data obtained in each configuration can be processed independently of the images or tables obtained in other configurations, a configuration designating an acquisition with the detector and the laser line in a determined position.
• X is an array of dimensions (i xd , i yd , i ⁇ ), and where i xd and i yd are the coordinates of an elementary detector along the Xd and Yd axes.
• X is an array of dimensions (i x s / i yS , i ⁇ ), and where i xS and i yS are the coordinates of an elementary source along the Xs and Ys axes. If the Laser line and the detectors are simultaneously moved between two successive acquisitions, we have:
• a and S are multidimensional arrays of which all elements are positive. As previously described, A and S are initialized then determined according to a factorization algorithm in non-negative matrices.
• the term non-negative matrix can be replaced by "array" because A can have a dimension greater than 2.
• each line of S corresponds to the emission spectrum of a source fluorescent, this spectrum being discretized according to N ⁇ channels.
• the algorithm starts with an initialization of the array A and the matrix S to the desired dimensions, and respecting the constraints of positivity.
• Table A is initialized randomly, while the S lines are initialized by reference spectra representing the searched sources. These spectra are determined empirically or according to tabulated values.
• the algorithm stems from a minimization of a function of cost or objective Q FMN .
• ⁇ , 3 is a positive real.
• 25 combines a distance between X and AS (Q FMN ) fe -
• ⁇ 4 ' is a real positive or strictly positive.
• the function to be minimized Q TM N combines a distance between X and AS ⁇ Q FMN ) fe - (- a second distance between the table A resulting from the current iteration, and the table A ° established during the initialization , or initial array A °, this second distance being able to be weighted by a real positive or strictly positive ⁇ 4 ' .
• ⁇ x is a positive or strictly positive real, with 1 ⁇ i ⁇ 4, i can also correspond to the index 4 ', ⁇ x also being able to correspond to the index ⁇ 4.
• At least one marker is introduced into a diffusing medium, so that the diffusing medium contains p fluorescence sources, the autofluorescence of the medium being able to be considered as a source of fluorescence.
• the diffusing medium contains p fluorescence sources, the autofluorescence of the medium being able to be considered as a source of fluorescence.
• At least one fluorescence acquisition is thus achieved by exciting the medium by a laser light source S with coordinates (i xS , i y s), the beam of this laser source being able to be focused, for example, in the form of a line.
• the fluorescence is detected by a detector D, which may comprise a plurality of detectors (i Xc ui Yd ) having a spectral dispersion capacity, these detectors being for example aligned along an axis Xd and thus forming a line of N xd elementary detectors.
• a detector D which may comprise a plurality of detectors (i Xc ui Yd ) having a spectral dispersion capacity, these detectors being for example aligned along an axis Xd and thus forming a line of N xd elementary detectors.
• the source and / or the plurality of detectors are displaced, for example in translation, the coordinates of the source and of each detector being respectively denoted (i X d, iyd) in a reference (X d , Y d ) and (i xs , i ys ) in a reference (X 8 , Y s ).
• a measurement pattern, or acquisition, is determined by a position of the plurality of detectors and a position of the source.
• the fluorescence signal produced inside the scattering medium is measured by each detector (xd, yd) placed in (ix d , iy d ). Such a signal is then separated according to N ⁇ length 10. waves, each detector (xd, yd) measuring the intensity at each wavelength i ⁇ .
• Table X obtained following measurements in each configuration, then corresponding to a series of acquisitions, is then processed by factoring the product of two non-negative matrices.
• a and S such as:
• the objective function is based on the calculation of the Euclidean distance between the array of X data and the tensor product A * S, other types of objective functions can be implemented within the scope of the invention, in particular an objective function based on the calculation of the divergence, including the Kullback Leibler divergence. Lee and Seung have determined for this function updating laws, which ensure the decay of the objective function in the case of a matrix X in two dimensions.

Applications Claiming Priority (2)

Publications (1)

Family

ID=40996512

Family Applications (1)

Country Status (4)

Families Citing this family (2)

Family Cites Families (7)

• 2009
  • 2009-03-11 FR FR0951505A patent/FR2942950B1/fr not_active Expired - Fee Related
• 2010
  • 2010-03-10 US US13/255,411 patent/US20120032094A1/en not_active Abandoned
  • 2010-03-10 WO PCT/EP2010/053008 patent/WO2010103026A1/fr active Application Filing
  • 2010-03-10 EP EP10707297A patent/EP2405800A1/de not_active Ceased

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events