WO2017012675A1

WO2017012675A1 - Method and device for smartphone mapping of tissue compounds

Info

Publication number: WO2017012675A1
Application number: PCT/EP2015/066913
Authority: WO
Inventors: Janis Spigulis; Matiss LACIS; Ilona KUZMINA; Aleksejs Lihacovs; Zigmars RUPENHEITS; Vladimirs Upmalis
Original assignee: Latvijas Universitate
Priority date: 2015-07-23
Filing date: 2015-07-23
Publication date: 2017-01-26

Abstract

The invention relates to imaging technologies, in particular to remote imaging of tissue chromophore and/or fluorophore distribution by means of a smartphone or a similar mobile device. Goal of the invention is to ensure easy use of smartphones (or similar mobile devices, originally comprising at least one camera, display, processing unit and battery) with appropriate software for remote mapping of tissue compounds. Invention proposes tissue chromophore and/or fluorophore mapping and/or indication of clinically critical values of their content on the display of smartphone by converting images of the same tissue area taken by smartphone camera under spectrally specific illumination and using the internal computing resources of smartphone for image processing. Five supporting device designs are proposed along with two methods used for image processing.

Description

Method and device for smartphone mapping of tissue compounds

Technical field

The invention relates to imaging technologies, in particular to remote imaging of tissue chromophore and/or fluorophore distribution by means of a smartphone or a similar mobile device.

Background art

Distribution maps of tissue compounds, e.g. skin chromophores, provide diagnostic information about the tissue condition and its changes during physiological processes like inflammations, post-therapy recovery, burn healing, development of tumours and bruises, etc. Three main chromophores that determine skin colour in normal conditions are melanin, oxy-haemoglobin and deoxy-haemoglobin (A R. Young, "Chromophores in human skin", Phys. Med. Biol. 42, 789, 1997). Content of another skin chromophore - bilirubin increases in result of liver insufficiency and/or mechanical interventions (bruises, post-surgery healing; as a reference, see L.LRandeberg et al., "Skin changes following minor trauma. " Lasers Surg. Med. 39(5), 403-413, 2007). Fast and reliable 2D-mapping of the named chromophores in pathologic cases is of interest for dermatologists, oncologists, forensic experts, intensive care physicians, family doctors and other professionals, as well as for wider audience interested in self-monitoring, e-medicine, personalized healthcare and similar aspects.

Tissue chromophore maps can be derived from large data sets of multi- spectral and/or hyperspectral reflection images, by means of spectral fitting algorithms with respect to absorption properties of the chromophores under interest (e.g. D. Jakovels and J. Spigulis, "2-D mapping of skin chromophores in the spectral range 500-700 nm", ./. Biophoton. v.3, No. 3. pp. 125-129, 2010 ). To avoid errors due to detection of tissue specular reflection, such systems usually comprise two mutually crossed polarizers - one in front of the illuminator and the other in front of the imaging camera (US2005030372 Al Method and apparatus for characterization of chromophore content and distribution in skin using cross-polarized diffuse reflectance imaging). Digital RGB cameras are also well-suited for chromophore mapping, since the red (R), green (G) and blue (B) spectral images of the target can be separated and/or specifically related (e.g. Kapsokalyvas D. et al.,. "Spectral morphological analysis of skin lesions with a polarization multispectral dermoscope. " Opt. Express. 21(4), 4826-40, 2013). To acquire spectral images, also spectrally narrowband tissue illumination can be used, e.g. by means of different colour LEDs (D.Jakovels et al, "Noncontact monitoring of vascular lesion phototherapy efficiency by RGB multispectral imaging", J. Biomed. Opt. 18(12), 126019, 2013). In this and similar studies three illumination spectral bands are exploited, each in frame of one photo-detection sensitivity band (R, G or B) of the image sensor; the three main chromophore content at each image pixel (or selected pixel group) are found by solving a system of 3 equations: log ^ = /_λ ^λζ M_K(A)L_B(A)^■ (∑i C_il(A)£_i(A))dA +

+ j£ M_K(A)L_G(A)^■ (∑i C_il(A)£_i(A))dA + j£ M_K(A)L_R(A)^■ (∑; C_il(A)£_i(A))dA

K = R, G, B

(1),

where C - concentrations of particular chromophores to be calculated, ε - extinction i i

coefficients of the chromophores, 1 , 1 , 1 - detected R, G, B signals from the white r OR 0G OB °

reference, 1 , 1 , 1 - detected R, G, B signals from the target tissue, M (λ), M (λ), M (λ)

R G B R G B

- R, G and B spectral sensitivity bands of the image sensor, L (λ), L (λ), L (λ) -

R G B

illumination spectra at the three spectral intervals, 1(λ)- absorption path length in tissue at the particular wavelength.

Skin fluorescence is useful technique for imaging of hidden tissue structures (US2014364745 Al), Multi-spectral tissue imaging). Skin fluorophore distributions can be mapped using specific lifetime imaging (as example - A.Ehlers et al., "Fluorescence lifetime imaging of human skin and hair", Proc. SPIE, v. 6089, 6089ON, 2006) or imaging of fluorescence photo-bleaching rates (J.Spigulis et al., "Imaging of laser-excited tissue autofluorescence bleaching rates, " Appl. Opt., v. 48, No. 10, pp. D163-D168, 2009). Fluorescence lifetime imaging devices usually are large-sized and robust, therefore not well- suited for clinical environment, while the known photo-bleaching rate distribution imagers typically need external computer for image processing. Wider applications of fluorescence techniques would require more compact designs. Portable handheld devices with built-in illumination, imaging and processing units able to map skin chromophores and fluorophores are known, as well (e.g. LV ' 14749 A), Multimodal displaying device for non-contact skin diagnosis; J.Spigulis et al., "Sklmager: a concept device for in-vivo skin assessment by multimodal imaging", Proc. Est. Acad. Sci. 63(3), 213-220, 2014). The proposed concept and prototype are at an early development stage and need further clinical validation.

There are now close to 2 billion smartphone users (http://www.emarketer.com/Article/Smartphone-Users-Worldwide-Will-Total-175-Billion- 2014/1010536). Many of them, especially those involved in healthcare sector, would like to use smartphone also as a tool for assessment of health condition and tissue composition. Smartphones, tablet PCs, laptop PCs and similar mobile devices of the latest generations comprise elements that are commonly exploited for mapping of tissue compounds - high- resolution digital RGB cameras, liquid-crystal displays, powerful processing units and white LED light source(s) on the rear panel. It was proposed earlier to use these features of smartphones for optical skin assessment (https://www.skinvision.com/; US2014313303 Al, Longitudinal dermoscopic study employing smartphone -based image registration; JP2014131121 A, Skin imaging system). External optical filters can be applied to the white LED and/or to the RGB camera of smartphone in order to modify spectral sensitivity of the imaging system. A smartphone with rear camera covered by special three -band transmission filter was used to estimate skin bilirubin content under the white LED illumination (C.A.Patil et al., Feasibility of mobile phone based transcutaneous bilirubinometry, Proc.SPIE, 9303, 2015). However, such filters with acceptable performance are expensive and need specific designs for simultaneous detection of several different chromophores. The front-camera of smartphone also can be exploited for tissue analysis, e.g. under liquid crystal display illumination (US2015005644 Al, Dermoscopic data acquisition employing display illumination). This technique eventually may be adapted also for tissue chromophore mapping. Spectrally specific illumination makes possible to map the distributions of skin chromophores by RGB cameras very rapidly, even by a single snapshot. Simultaneous illumination of tissue by discrete spectral lines allows extracting several monochromatic spectral images from single RGB image data set (WO2013135311 Al, Method and device for imaging of spectral reflectance at several wavelength bands). Snapshot mapping of three main skin chromophores under triple-laser illumination has been demonstrated recently (J.Spigulis and I.Oshina, "Snapshot RGB mapping of skin melanin and haemoglobin", J.Biomed.Opt, 20(5), 050503, 2015). This approach might be efficient if smartphone is used for image acquisition.

Generally, the regarded background information confirms that smartphones and/or similar mobile devices might be applied efficiently for distant mapping of tissue compounds if appropriate methods and supporting devices become available.

Disclosure of the invention

Goal of the invention is to ensure easy use of smartphones (or similar mobile devices, originally comprising at least one camera, display, processing unit and battery) for remote mapping of tissue compounds.

Invention proposes tissue chromophore and/or fluorophore mapping and/or indication of clinically critical values of their content on the display of smartphone by converting images of the same tissue area taken by smartphone camera under spectrally specific illumination and using the internal computing resources of smartphone for image processing. Five supporting device designs are proposed along with two methods used for image processing.

Brief description of the drawings

Fig. l presents design scheme of the embodiment 1 without smartphone (a) and with smartphone (b).

Fig.2 specifies design of the ring light source covered by diffusive film and polarizer of the embodiment 1.

Fig.3 illustrates design of the embodiment 1 with conical shielding wall.

Fig.4 shows design scheme of the embodiment 3 with cylindrical (a) and conical (b) shielding wall.

Fig.5 presents the measured emission spectra from mono-coloured displays of the Sony Xperia Go smartphone: B - blue, G - green, R - red.

Fig.6 provides scheme for image capturing by front camera of smartphone with side-turned display illumination of the tissue. Fig.7 illustrates design scheme of the embodiment 4 without (a) and with (b) smartphone.

Fig.8 explains optical system of the embodiment 5 providing tissue illumination at several laser wavelengths.

Fig.9a and 9b specifies design of laser illumination system of the embodiment 5. Fig.10 presents the scheme of image-processing algorithm for mapping of tissue chromophores.

Fig.11 presents the scheme of image-processing algorithm for mapping of tissue fluorophores.

Embodiment 1. Universal platform for tissue chromophore mapping by smartphone.

The proposed device (Fig.l) comprises a flat platform 1 with first polarizer-covered opening 2 for the rear camera of a smartphone 3 or similar mobile device with installed appropriate software. The platform 1 is covered with a sticky non-smearing substance able to fix the smartphone, tablet computer or other mobile device with its camera against the opening 2 during the image acquisition. This design is universal because any model of smartphone, tablet computer or other mobile device can be used, independently on its size and specifications.

On the other side of platform 1 a compartment 4 for rechargeable batteries and electronic circuits is mounted, as well as non-transparent cylindrical light shielding wall 5 that also ensures fixed distance between the camera objective and the examined tissue, placed under the cylinder in contact with it. In order to image smaller tissue areas under examination, on the bottom of shielding cylinder 5 manually tuneable iris diaphragm 6 or, alternatively, a set of shielding rings with internal openings of different diameters, is mounted.

Spectrally- specific illumination of tissue is performed by a ring of suitable narrowband LEDs 7 with internal diameter larger than that of the opening 2 (Fig.2). The LED ring 7 is mounted on the down- side side of platform 1 within the shielding cylinder 5 and is covered by a ring of diffusive film 8 that provides uniform illumination of the target area, and, behind it, by a ring of polarizing film 9 with orthogonal orientation relatively to the first polarizer 10, so preventing detection of the tissue surface-reflected radiation. The ring 7 comprises a set of narrowband LEDs emitting at least in the blue, green and red spectral ranges. Each emission colour is sequentially 0.1...1.0 second switched on by a driver mounted in the compartment 4 for taking one or several spectral images; the driver is managed by smartphone's software using either cable or wireless connection. The LEDs can be also switched on simultaneously to provide white illumination for taking a colour photo of the tissue under examination. All acquired images are further processed using the method described below; the calculated tissue chromophore maps appear on the screen of smartphone within few seconds and can be examined visually and/or saved for further analysis in the smartphone memory card.

Another design option of embodiment 1 is presented on Fig.3. To ensure better access to curved, caved or hard-to-reach tissue areas, the cylindrical shielding unit is replaced by a conical shielding nozzle 11 with correspondingly reduced image field.

Embodiment 2. Universal platform for tissue fluorophore mapping by smartphone.

Device comprises most of the elements of the embodiment 1, with some modifications to adapt the device for fluorescence measurements. The ring-shaped LED illuminator 7 is uncovered and comprises one or several LEDs suitable for tissue fluorescence excitation, e.g. emitting in the spectral range 400-450nm, and one or several white LEDs for obtaining colour photos of the tissue area under examination by the smartphone camera. Instead of the first polarizer 10, the opening 2 is covered by an optical filter, cutting-off the wavelengths used for fluorescence excitation.

LEDs are operated by the smartphone software; they are continuously emitting for a predefined time interval. Fluorescence images of the same tissue area are recorded by smartphone camera in video-mode for at least 20 seconds with framerate at least 1 fr/s. The B-output signals of each image pixel or selected pixel group are used for reference, while the G- and R-outputs are imaging the tissue fluorescence and detecting its photo-bleaching over time. If several fluorophores are excited, their photo-bleaching rates may differ, causing temporal changes in output signals of the G- and R-detection bands. The tissue flourophores and/or their groups are identified and mapped using the method described below; the resulting maps and/or videos of tissue fluorophore distribution appear on the smartphone display and can be saved for further analysis in the memory card of smartphone. Embodiment 3. Compact design for tissue chromophore and/or fluorophore mapping by smartphone.

In order to reduce size of the embodiment 1 and/or embodiment 2, the platform 1 represents a disc with external diameter equal to that of the shielding cylinder 5 or basement of the shielding cone 10 (Fig.4). Both power supply and management of the LED ring 7 operation is provided by the smartphone battery and the installed appropriate software, respectively, via a flexible cable 12 connected to the USB port of the smartphone. Image processing, display and saving of the tissue chromophore and/or fluorophore maps is performed as described above. This design is handier than the two previously described, but it is not that universal due to limitations of LED current provided by the battery of the specified model of smartphone or similar mobile device.

Embodiment 4. Smartphone holder with light-turning element for tissue chromophore mapping.

Our laboratory measurements confirmed that mono-coloured display of smartphone can emit relatively narrow spectral bands, comparable to those of LEDs (Fig.5). It opens the possibility to perform spectrally selective tissue illumination directly by smartphone' s display, avoiding the need of external multi-coloured LEDs for obtaining the set of tissue spectral images. Front camera of smartphone (usually located in the upper corner of front panel) can be used for image acquisition; however, the drawback is uneven illumination of the camera's field of view, if smartphone is used without any additional components.

To assure uniform illumination of the tissue area facing the front camera, micro- structured prism film (http://www.film-optics.co.uk/index.php/lighting) or similar light turning element is proposed to be attached to the smartphone display, with respect to the geometrical condition for distance x between the front panel of smartphone and the examined tissue: x = A _* ctg a, where A is the distance between the middle-points of the display and the front camera, respectively, and a is the light turning angle (Fig.6).

The device according to the present embodiment represents a hollow holder with light- shielding walls 13, placed on the tissue surface. Holder has and upper surface adapted to size of the smartphone with properly oriented micro- structured prism film (or similar light turning element) 14 supposed to be in contact with the illuminating display of smartphone (Fig.7). The upper surface also comprises an opening for the front camera of smartphone, possibly covered by a properly oriented polarizing film to minimize detection of surface- reflected light. The upper surface of holder is fixed at the distance x from the tissue surface. Extension of the shielding wall 15 provides optimal field of view of the front camera.

Alternatively, display of the smartphone remains open while a sloped mirror, transparent wedge or other optical element turning the front camera's field of view for the angle a observing the same geometrical condition for the distance x) is attached to the front camera of smartphone so that the display- illuminated area of tissue is optimally imaged.

Embodiment 5. Universal platform for single-snapshot mapping of tissue chromophores.

Our previous studies demonstrated that uniform illumination of tissue simultaneously by a fixed number of discrete spectral lines assures extraction of the same number of monochromatic spectral images from a single RGB image data set, with their further conversion into chromophore maps (J.Spigulis and I.Oshina, "Snapshot RGB mapping of skin melanin and haemoglobin", J.Biomed.Opt, 20(5), 050503, 2015). This concept is implemented in device-5 for smartphone snapshot mapping of tissue chromophores.

Device comprises elements 1-5 of the device-1 (Fig. l), as well as the ring-shaped polarizing film 9. For tissue illumination the LED ring 7 is replaced by a flat diffusive disc 16 with round central opening, made of a milk- glass or similar material. Disc 16 is tightly covered by another ring-shaped disc 17 of the same thickness but made of a transparent material, e.g. glass, with polished 45deg-sloped external edge; the upper surfaces and sloped edges of both discs are mirror-coated (Fig.8). Inside the shielding cylinder 5 a number of laser modules 18 emitting spectral lines with selected wavelengths are fixed so that their output beams are directed to the sloped mirrored edge of the external disc 17 and after reflection are directed radially to the diffusive disc 16. The scattered in disc 16 laser light provides uniform illumination of the examined tissue surface at all exploited laser wavelengths (Fig.9). Alternatively, the external disc 17 is replaced by a set of radially oriented flexible optical fibres or other appropriate light guide(s) that deliver the laser radiation to the diffusive ring 16 from the laser modules that are placed elsewhere.

If compared with known laser illumination methods that exploit beam-expanding or scattering elements located between the laser source and target area, the proposed design provides more uniform illumination of the selected tissue surface because disc 16 acts as an isotropic surface emitter, not as a point-source.

The single snapshot of selected tissue area is taken by smartphone rear camera when all lasers are switched on. Image processing for obtaining tissue chromophore maps on the smartphone display is performed by software installed on the smartphone using the algorithm from the above-cited publication.

Method for tissue chromophore mapping

To determine spectral reflectance or optical density in reflection mode as proposed by eq. (1), a reference signal from specific reflector is needed. Most commonly a white reflector (e.g. white ceramic plate, white paper) is used for reference. However, it may cause significant errors in tissue chromophore maps, especially if specular reflection from the tissue surface if prevented by combination of linearly polarized illumination and detection via orthogonally oriented polarizer and only diffusely scattered light is detected. The scattering anisotropy factor g, defined as g = <cos φ>, where φ photon deflection angle at single scattering event, may be essentially different within the reference material and within the tissue. From this point, more reliable reference could be specifically selected area(s) of the tissue under examination, thanks to similar internal structure and scattering properties. Invention proposes to exploit as reference for chromophore mapping the area(s) of healthy tissue adjacent to the pathology region or sufficiently close to it - e.g. in cases when the adjacent part is inflamed or when the pathology covers nearly all field of view. Smartphone software establishes equally sized regions of interest (Rol) for further analysis - e.g. at least one in central (pathology) region of the image and four at all corners of image (or a different number of differently located Rols), with subsequent averaging of the reference values of reflected intensity. In the cases when the adjacent to pathology part of tissue is inflamed or when the pathology covers nearly all field of view, additional reference image has to be taken from completely healthy tissue near to the pathology region.

The scheme of image-processing algorithm is presented on Fig.10. The process of obtaining chromophore distribution maps starts with reference image obtaining 801. For reference data image of patient skin without damage is used. The reference images are obtained for every illumination wavelength. Then operator chooses priority chromophore mapping 802 which are most interesting - PH. The next step 803 is obtaining 3 images I_; - one per one illumination wavelength, where every image is dedicated to chromophore i. After that 2 algorithm variables are initialized for every chromophore i mapping - split factor for images Nj 804 and speed factor SF_; 805. Speed factor SF specifies how fast algorithm converges and is adjusted for computing platform according to requirements for mapping obtaining speed and available computing resources. Split every image pixels into groups 807. On every group pixels intensity is replaced with average intensity of group's pixels. After that 808 using average intensities are solved equation system (1) or using mathematical optimization found values for from equation (1) minimizing error over all pixels between intensities on captured images Ij and calculated using (1). Obtained values are stored for later post processing. Every loop 806-809 produces new values for every pixel on image Ij. New values for Ni are calculated 809 using current values Ni and speed factor SFj. If for any of i (Image I_; width / Nj < 1 or Image I_; height / Nj < 1), collected chromophore distribution mapping value sets are analyzed 810. During analyzing are removed values < 0 and values that differ from the rest too much. The final stage is creating chromophore map using the filtered values.

After chromophore mapping, the smartphone software calculates and shows on its display value(s) of physiologically and clinically significant criteria - spectral reflectance k( ) = Ι(λ)/Ι₀(λ) (2), where Ι(λ) and Ι₀(λ) are intensities detected at wavelength Dfrom the target and reference, respectively, and/or optical density

Οϋ(λ) = log k( ) (3), and/or the pathology criterion

Z = C(pat)/ C(hea) (4), related to the derived concentrations of particular chromophore in the pathology region C(pat) and in the reference (healthy tissue) region C(hea).

Relative concentrations of chromophores are calculated from the measurement data by solving eq. (1) or by any other suitable algorithm. Then the smartphone software compares the obtained values with pre-defined clinical threshold values related to severity of the examined tissue pathology and indicates the severity level of the displayed values by different colour coding, flashing the displayed numbers at different frequencies, sound signalling, or similar.

Method for tissue fluorophore mapping

Invention proposes to map tissue fluorophores or their groups accordingly to the recorded photo-bleaching rate distributions as detected separately in the G- and R-channels of the smartphone image sensor, and additionally to characterize the dynamics of photo- bleaching by providing sequential parametric images formed by the ratios of the G- and R- signals recorded from each pixel or group of pixels over time (e.g. by creating a parametric video file). Both static fluorophore distribution maps and the dynamic video-recordings are displayed on the smartphone touch-screen.

The processing procedure involves the following steps:

1. RGB image snapshot under white LED illumination R_{x y}=f[R,G,B]

2. Periodic capture of the set of spectrally filtered tissue AF images during the 20 seconds with lfr/sec framerate under continuous 405 nm LED excitation

3. Creating from AF images a coordinate-color-time data array A_Xiyit=[R,G,B,t_sec]

4. Calculating the difference of color components between AF image at excitation start moment (t=0) and AF image of time moment t (t=l :20 sec): D_{x yit}=G_t=o - Rt 5. Define the mask according to the threshold: if D_{x y t}>0 then M_{x y t}=255, else

M_x,y,t=0.

6. Mark areas of R_{x y} image within mask Μ_{χ γ Ι}.

7. Creating an image sequence R_{x y} within the masks M_{x y t}

The scheme of image -processing algorithm is presented on Fig.11, where abbreviation AF means "autofluorescence".

Claims

1. A device for mapping of tissue chromophores on a display of smartphone or similar mobile device using transformations of spectral images taken from the same tissue area by RGB digital camera of smartphone at sequential tissue illumination by narrowband radiation with different central wavelengths within the RGB sensitivity interval, the device comprising a flat sticky platform with a first polarizer-covered opening for the rear camera of smartphone or similar mobile device with installed appropriate software, a compartment for rechargeable batteries and/or electronic circuits, a ring of suitable light emitting diodes (LED) covered with diffuser and polarizing film oriented orthogonally to the first polarizer, situated around said opening at the other side of platform and placed within a cylindrical or conical light shielding wall which is also adapted to ensure fixed distance between the camera and the examined tissue.

2. The device according to Claim 1, wherein the platform represents a disc with external diameter equal to that of the shielding cylinder or cone basement and both power supply and management of the LED ring emission is provided by the battery and software of the smartphone or similar mobile device, respectively, via flexible cable connected to the USB port of the smartphone, while the captured images are processed by appropriate smartphone software.

3. The device according to Claim 1 or 2, wherein to assure mapping of tissue fluorophores the first polarizer is replaced by cut-off optical filter and the LED ring comprises one or several light emitting diodes suitable for tissue fluorescence excitation, e.g. emitting in the spectral range 400-450 nm, and at least one white light emitting diode for tissue illumination to ensure capturing of colour photo of the tissue.

4. The device according to Claim 1 or 2, wherein spectrally specific sequential tissue illumination is provided by mono-coloured display of smartphone or similar mobile device with appropriate software and tissue images are taken by front camera of the smartphone, providing that a micro-structured prism film or other light turning element is attached to the smartphone display so that the display-emitted light is side-directed and provides optimal illumination of the tissue area facing the front-camera of smartphone and the distance between them is x = A _* ctg a, where A is the distance between the middle-points of the display and the front camera, respectively, and a is the light turning angle, where the light shielding is ensured by means of a hollow smartphone holder placed on the tissue surface and having upper surface comprising an opening for the front camera objective, possibly covered by a properly oriented polarizing film; alternatively, the upper surface of the holder comprises a sloped mirror, transparent wedge or another element that turns aside field-of-view of the front camera for angle a so ensuring optimal imaging of the display- illuminated tissue surface placed at the distance x from the front panel of smartphone.

5. The device according to Claim 1 or 2, wherein the LED ring covered with diffuser is replaced by a disc- shaped scattering diffuser with round central opening which is radially side-illuminated by several laser beams with different wavelengths, emitted from a number of laser modules placed inside the cylindrical wall, using appropriate optical element for laser beam management, e.g. external transparent disc with sloped edge; alternatively, laser modules are placed elsewhere and laser beams are radially illuminating the disc-shaped diffuser via flexible optical fibres or other light guide(s).

6. A method for tissue chromophore mapping providing that selected area(s) of healthy tissue adjacent to the pathology region or sufficiently close to it is/are exploited as the reference(s) for determination of spectral reflectance and/or optical density of reflectance by defining specific areas of interest at the images captured by smartphone camera and using the recorded reflected signals for quantifying severity of the particular pathology by their comparing with pre-defined threshold values of spectral reflectance, optical density and/or the criterion [C(pat)/C(hea)], where C(pat) and C(hea) are the derived chromophore concentrations in the pathology region and in the healthy tissue region, respectively, with indicating the severity level(s) of pathology(-ies) on the smartphone display by different colours, flashing signs, sound signal(s), or similar.

7. A method for mapping of tissue fluorophores using video-images taken by RGB digital camera of a smartphone or similar mobile device under temporally stable irradiation by light emitting diode(s) or other light source(s) emitting wavelength(s) fitting within the absorption band(s) of particular fluorophore(s), typically in the violet-blue spectral range 400-450 nm, providing that fluorescence images of the specified tissue area are sequentially recorded for at least 20 seconds with a period 1 second or less, wherein the B- output signal of each image pixel or selected pixel group is used for reference while the G- and R-output signals are used to monitor tissue fluorescence and its photo-bleaching over time, resulting in identification of fluorophores or their groups by analysis of parametric maps of photo-bleaching rate distribution and/or video file(s) or similar format that properly reflects temporal changes of the parameter k = G/R, where G an R are the G- and R-signal output value for each image pixel or specified group(s) of pixels, respectively.