DE19630381C2 - Method, device and use of a device for the detection of blood flow and / or the flow of intracorporeally flowing liquids in human or animal tissue - Google Patents

Description

The invention relates to a method, a device and the use of a device for the detection of blood flow and / or the flow of intracorporeal fluids in human or animal tissue.

The skin as a border organ between humans and the environment fulfills a variety of functions. It serves to fulfill regulatory and immunological tasks and, last but not least, as a sensory organ. The skin is roughly composed of the epidermis and the underlying layer, the corium consisting of nerves, muscles and capillaries. The interaction of these muscles, nerves and capillaries regulates the microcirculation and controls all other tasks that are the responsibility of the skin. A determination and control of the blood flow to the skin can now serve to determine fluctuations or disorders thereof and to support a medical diagnosis. Below is just an extract of the various application examples:

• - Diagnosis of skin diseases, e.g. B. Sclerodermia, psoriasis
• - Localization of arterial sclerosis symptoms
• - Assistance in the detection of diabetic Microangiophathy
• - Observation of the arterial vasomotion
• - Monitoring of sympathetic functions in the Regional anesthesia
• - Blood flow control during transplants, etc.  
• - Blood flow control during transplants, etc.

Laser Doppler systems have been used for decades Skin vascular diagnostics used. The biggest limitation of the conventional laser Doppler systems are based on their low effective depth of penetration and analysis "direction-independent" signals. This reduces the Use on measuring the microcirculation of the skin, being a measuring volume the size of a hemisphere with a Diameter of max. 1 mm can be examined. Furthermore deliver the devices for clinical use that have been used up to now the blood flow to the skin from methodological and metrological No comparable measurement values for reasons. The users of these conventional systems, e.g. B. flow meters are included passed, mainly the time behavior of the measurement signals defined stimulations to assess the microcirculation to use.

DE 195 06 484 A1 already discloses a method and a method Device for selective non-invasive laser myography (LMG) known. With this method or device Muscle activities selectively also in deeper tissue layers be measured. With a semiconductor laser with a large coherence length become photons through a short optical fiber into the tissue irradiated. The photons emerging from the tissue are detected at greater distances from the point of radiation. Thereby the photons are due to the muscle fiber activities frequency shifted by the optical Doppler effect and it do not arise from overlaps with statically scattered frequency shifted coherent photon intensity beats with the Doppler frequency. Thus, it is possible through detection of the photons emerging again with increasing distance from Irradiation point selective information regarding the Obtain muscle activity from specific tissue depths.  

US Pat. No. 4,476,875 A describes a method and a method Device for detecting blood flow in a tissue known. For this purpose, photons are inserted into the Tissue sent in, the being relatively narrow to that Irradiation location adjacent surface areas again emerging photons by means of at least two separate ones Photodetectors can be detected. From the output signals of this A signal is derived from each photodetector, which also fluctuations in intensity due to the Doppler frequency shift. This way processed signals of the at least two photodetectors are finally subtracted from each other by one measurement with respect to the blood or fluid flow. Since the emerging photons in such areas be the i. w. equidistant from the irradiation point of the photons are the meaningfulness of the measured values obtained in this way only limited. In particular, depth-selective surveys of the Blood flow or flow of intracorporeal fluids in the tissue using this method or device not possible.

Finally, DE 38 44 651 C2 describes a device for Determine the backscattering of light in animal and known to human tissues, in the light by means of a Light guide is radiated into the tissue and over at least two light guides the backscattered light is, this receiving light guide radially spaced differently from the incident light guide are. The device is used to change the size of Determine particles in the tissue. For example, the Mitochondrial size changes are detected, so that a early detection of brain edema, for example, is possible.

In contrast, the object of the invention is a method, a Device and a new use of a device  to indicate with whom a depth-selective, non-invasive Detection of blood flow and / or flow flowing intracorporeally Liquids in biological tissue is possible.

This task is the subject of the Claim 1 solved. Advantageous refinements of the method are given in claims 2 to 4.

Concerning. the device does this task by the subject of Claim 5 solved. Advantageous embodiments of this Device are specified in claims 6 to 12.

Concerning. the new use, the task is through the subject of claim 14 solved.

This device or this evaluation method use the Property of the interaction of electromagnetic waves tissue and blood and / or fluid components. Because of a sufficiently small wavelength and with that connected, adequate ratio of wavelength to geometric dimensions of the body to be detected or Tissue, the spectral range is suitable from visible to infrared electromagnetic waves. At the same time sufficient detection depth in biological tissue is reached. This procedure is non-invasive and the one from the Interactions that arise are proportional to Speed, number and depth of each yourself moving blood and / or fluid components, so that from this information clearly, especially a relative one Change in flow rate or the like is detectable and assignable is. Investigations both in everyday clinical practice and in special, medical, pharmacological or industrial Questions about depth-selective detection of blood flow  and / or intra- and / or extracorporeally flowing liquids can with this device or this Evaluation procedure extremely simple, painless and perform reproducibly.

The invention is based i. w. then, by means of laser light or the like, coherent and monochromatic electromagnetic radiation the skin surface or tissue surface of the examined Digits in. The photons penetrate the tissue and are according to the optical parameters of the tissue scattered or absorbed. Since the spread with a change the direction of propagation of the photons goes, too Photons remitted from the tissue, d. H. to the surface of the Scattered tissue or skin and emerge again from the Fabric. This remission from the tissue again emerging photons shows a decreasing intensity increasing distance from the point of entry of the photons. A Another characteristic of biological tissue is that light not evenly, d. H. isotropic, scattered in all directions is, but a forward characteristic in the spreading process preserved. This is expressed in the so-called Anisotropy factor g for scattering processes, the one for tissue Value g assumes approximately 0.9. A value g = 0 would be isotropic, a value g = 1 correspond to pure forward scatter.

Using a simple model is explained below to what extent detection of the remitted photons a conclusion about the condition of the tissue or the blood flow and / or intra- and / or extracorporeally flowing liquids is possible: B. photons that are about 5 mm apart the point of irradiation of the photons from the tissue emerge, then with a high probability of it be assumed that these emerging photons through different scattering processes in about one semicircular or similar trajectory through the tissue  have moved. Due to the special arrangement of the Measuring device or the implementation of the evaluation process however, ensure that the start of the trajectory at the point of entry of the Photons and the end of the trajectory at the measuring point of the emerging photons. Unless they come out again Photons any information regarding the movement of the Blood flow and / or intra- and / or extracorporeally flowing In any case, liquids should be assumed be that the directly next to the irradiation location again from the Tissue leaking photons only information regarding wear below the surface of flowed tissue layers, while those at a greater distance from the irradiation site emerging photons digestion also over deeper flow Can give layers of tissue. This model consideration thus illustrates that by detecting from the tissue again emerging photons with increasing distance from Irradiation location selectively information from certain tissue depths can be obtained.

It is known to measure moving, scattering particles the optical Doppler effect is used. Thereby light experiences in the scattering process a frequency shift that is proportional to the speed of the moving particle increases. Under Consideration of the Doppler effect can, for. B. in superficial tissue layers determined the blood flow in the tissue will. For an optimal Doppler signal of blood flow and / or intra- and / or extracorporeally flowing liquids Preserving in deeper tissue layers is one Light wavelength of the light source, in particular of the laser, required, which is only slightly absorbed by the tissue. It therefore there are wavelengths in the range from about 600 nm to about 1200 nm, preferably at about 820 nm.

In the literature it is discussed now and then that coherent Laser light when beaming into the tissue due to the large number  the scattering processes could lose their coherence characteristics. However, by interferometric studies show that a certain proportion of photons in the larger Leave the tissue at the distance from the radiation site with which incident photon beam can interfere with what undoubtedly it must be concluded that the coherence characteristics of these scattered photons are still present. So it is but also possible at greater distances from the point of irradiation still Doppler signals with the corresponding Frequency shift of the photons emerging again detect. The photons mix with Doppler shifted frequency with photons that do not have Doppler Have experienced displacement, i.e. only from a rigid or immobile matrix were scattered. At the detection site at the The tissue surface thus creates an intensity beat between frequency-shifted and non-frequency-shifted Photons. This leads to a local speckle pattern, the Intensity varies with the Doppler frequency and thus from an optical detector can be measured.

In principle, the signals are evaluated in the form that two detectors, preferably symmetrical to the irradiation location record remitted photons. The output signals of this Detectors are evaluated and processed accordingly to the desired information or statements regarding the Blood flow and / or intra- and / or extracorporeally flowing Liquids.

In summary, it can be said that such Evaluation method or such a device especially in Area of the "therapeutic window", ie at wavelengths in the range from 600 nm to 1200 nm, in which the scattering of the irradiated photons is not negligible, is feasible. The optical absorption from scattering of Light in human tissue can pass through the  Photon transport theory are described in more detail. Here will follows the path of a photon scattered into the skin. The Photon experiences either one at the individual local spreaders elastic scatter or it is completely absorbed. Out of it can be used for laser light in the red wavelength range (600 nm) or the infrared wavelength range (1200 nm) Determine depth of penetration and the spreading process. Although the so-called mean free path is relatively short, light can penetrate this wavelength range deep into the tissue because the scatter is mainly in the forward direction (so-called Mie scattering), the scattering processes are essential are more common than that of absorption and absorption in the Tissue for this wavelength range is low compared to other wavelengths. The spread of light in the tissue is reduced of transport theory described by the following parameters: Anisotropy factor, scattering coefficient, absorption coefficient, mean free path.

An overall view of the theoretical as well as performed experimental studies indicate that with the inventive method or the inventive Device annular interference structures in concentric Location regarding the irradiation location are available. With increasing the photons also provide a lateral distance to the point of incidence higher probability in the tissue larger distances back and accordingly penetrate deeper into the tissue. To the Information contained in the photon state about movements of the To be able to evaluate illuminated tissue should Light source specific properties, such as adequate Have coherence length, be monochromatic and in single Mode state can be operated.

An important prerequisite for obtaining the desired one Information is a sufficiently high coherence length so that a Interference pattern on the surface of the invention  Device can be achieved. The emergence of the interference pattern is due to the assumption that photons close to the Tissue or skin surface are scattered, none Experienced changes in frequency, but not so to speak scattered photons with those in depth moving particles, i.e. on the moving blood and / or Liquid components are scattered and thereby a Experience frequency change, interfere. So will that frequency-shifted scattered light, which on moving Particle was scattered with quasi-frequency-shifted Original light, made to coincide on the detector surface, there is a beat frequency or an interference pattern. Around these beat frequencies from deeper tissue layers too received, the use of a wavelength in the range of 600 nm up to approx. 1200 nm required, whereby also on a sufficient coherence length of the light source must be observed should. It could be shown that typical Interference patterns are also detectable for large tissue depths and that the information with increasing distance of the Detector area comes from increasing depth of tissue. This Evidence is also available for large lateral distances Detector area from the irradiation location in a range of up to approx. 15 mm has been successfully carried out. However, appear lateral distances of up to 30 mm in practice to be possible.

As very particularly advantageous in the invention Device proves the measure that the others Area areas or the assigned detectors in pairs adjacent to each other and i. w. in a row one behind the other are arranged, each pair a different distance from the has the first area and the distances between adjacent pairs are in particular equidistant. So there are two Detector surfaces provided in pairs next to each other and symmetrical to the irradiation location of the photons in a defined  Distance from this are arranged. Each of the pair Surface areas or detectors thus represents a Measuring volume of the tissue to be analyzed. Any of those paired Detectors should enter due to the light distribution in the tissue record equivalent signal.

The device according to the invention has a number of advantageous embodiments.

It is, for example, according to a first advantageous one Embodiment of the device according to the invention possible that the light source has at least one end face of the tissue attachable or attachable optical fiber piece, or a Collimation optics for focusing the laser light on the Tissue or skin, is subordinate. By this measure a locally defined radiation of the photons into the Fabric guaranteed. The optical fiber piece should preferably a mono-mode fiber with a diameter of approx. 5-15 µm to be the light output of the semiconductor laser to be able to transfer. However, multi-mode Fibers with a diameter of approx. 300 µm and larger be used. Depending on the version can also on Optical fiber piece can be dispensed with, for example, if that Laser light using collimation optics on the Skin surface is focused.

Furthermore, it has proven to be extremely advantageous that the Detectors one or the front of the tissue have attachable optical fiber, which a photodiode or the like. is subordinate. Thus, the detector surface consists of the Polished glass fiber end faces, their spatial Luminous flux distribution is designed so that the received light each on the sensitive area of a photodiode is forwarded.  

To improve the signal quality, the use of one of the Light source downstream or the detectors upstream polarization filter proved, the If necessary, an additional absorption filter is assigned to detectors can be. These filters can either be evaporated or be designed as a separate glass insert.

Advantageous wavelengths that are preferred as semiconductor lasers trained light source are in the range of 600 nm to about 1200 nm, preferably around 820 nm. This wavelength range is also called the "therapeutic window".

In principle, of course, it is also possible to use only one only additional area or detector per Use detection channel. However, it turns out in this If the measured value acquisition is due to a less favorable signal Noise ratio as considerably more complex.

As the practical studies have shown, they are further surface areas or the corresponding detectors Detection of the photons emerging from the tissue to a maximum distance of about 15 to 30 mm from the first Area arranged. This maximum range is i. w. of the used wavelength and the associated  Absorption coefficient and the coherence length of the used light source dependent.

It has proven to be particularly advantageous in terms of Evaluation of the signals from the detectors proved that those of paired areas or from the corresponding Detectors detected two signals, the two of them Inputs of a differential amplifier are supplied. Of the Using a differential amplifier has the advantage that the static signal component of the paired detectors due to the amplification only that at the inputs applied input voltage difference is compensated and thus i. w. only the dynamic fluctuations in intensity, which by the optical Doppler effect and thus the moving blood and / or fluid components are caused, be reinforced. This measure leads to a significant one Improvement of the signal-to-noise ratio and thus to one significantly more accurate signal evaluation, since only the on Movements of tissue resulting in fluctuations in intensity be reinforced.

The fact that the signals from the detectors, possibly after a Digitization, including an adaptive filter function and subjected to a cepstrum analysis function remains on the one hand, the useful signal is unaffected due to the filtering and can also be characteristic, changing Frequency components of the signals are made visible.

According to a further advantageous aspect of the invention the light source as well as the detectors and electronic Components such as preamplifiers, differential amplifiers and / or Analog / digital converter together in one measuring head, the Can be placed flat on the tissue or skin is housed, the measuring head only by means of electrical conductor with the evaluation unit, in particular the  Processor that can be connected. This measuring head can, for example, approx. 130 mm high and approx. 15 mm wide and with a rounded side surface be trained. However, other housing designs are also available conceivable depending on the individual requirements. The whole Device with the exception of the processor is thus on one attached single carrier plate or board or the like, which in a closed, physiologically safe and shielded Plastic housing is included.

A particularly advantageous embodiment of the entrance described evaluation method according to the invention in being a light source with a coherence length larger than 10 cm and you use them again emerging photons at a certain distance of the first area, preferably at least at the same time in two closely adjacent or symmetrical to the first area arranged surface areas, detected. By this measure is the prerequisite for a particularly good signal / noise Relationship created.

It has proven to be advantageous that the detected signals under two surface areas other leads a differential amplifier function and possibly an adaptive filter function and possibly a frequency and / or cepstrum analysis. Through this type of procedural signal evaluation can be a precise analysis of the Blood flow perfusion can be obtained.

The invention is described in the following Description of the exemplary embodiments with reference to the drawings explained in more detail.  

Show it:

Fig. 1 is a schematic view of a first embodiment of the, placed on a fabric device of the invention in side view,

Fig. 2 shows a second embodiment of the device according to the invention in side and bottom view,

Fig. 3 shows a third embodiment of the device according to the invention in a schematic representation;

Fig. 4 is a block diagram of an adaptive filter function and

Fig. 5 is a block diagram of a cepstrum analysis function.

The device 10 shown in FIGS . 1 and 2 for depth-selective detection of blood flow and / or intra- and / or extracorporeally flowing liquids in human, animal or the like tissue 12 has a light source 14 , in particular a semiconductor laser, for emitting photons into the tissue 12 or the blood vessels. The device 10 is placed with a carrier plate on the tissue 12 or the skin 18 of the tissue, with photons entering the tissue 12 or the blood vessels through a first region 16 , which is well defined locally. The photons are partly scattered, partly absorbed in the tissue 12 or the blood vessels, some possible photon paths 66 , 68 being illustrated and schematically in FIG. 1. It is clearly visible that the photons emerge again and again from the tissue 12 with increasing penetration depth 64 from the first region 16 .

Furthermore, the device 10 has a plurality of detectors 20 for detecting the photons emerging from further surface areas 22 of the skin 18 or of the tissue 12 . The further surface areas 22 are spaced from the first area 16 at different distances.

According to the exemplary embodiment in FIG. 1, the light source 14 is assigned an optical fiber piece 24 which can be placed on the face of the fabric 12 . It can be seen from the exemplary embodiment in FIG. 2 that, instead of the light-conducting fiber piece 24 , collimation optics 26 can also be used to focus the laser light on the tissue 12 or the skin 18 .

The detectors 20 each have an optical fiber 28 which can be placed on the face of the tissue 12 and which is followed by a photodiode 30 or the like.

The light source 14 is followed by a polarization filter and upstream of the detectors 20 . Furthermore, absorption filters 34 are optionally inserted between the optical fiber 28 and the photodiode 30 .

The wavelength of the semiconductor laser is in the range of approximately 600 nm to about 1200 nm, preferably at about 820 nm.

As can be seen in particular from the exemplary embodiment in FIG. 2, the further surface areas 22 or the associated detectors 20 are arranged in pairs adjacent to one another and generally lying one behind the other in row 38 , each pair 36 being at a different distance from the first area 16 and the distances adjacent pairs 36 are in any case equidistant in the exemplary embodiment. It goes without saying that other distances between the individual detectors 20 with respect to the first region 16 can also be selected, this is measured on the basis of the special requirements of the respective system and on the basis of the specialist knowledge of the person skilled in the art. The further surface areas 22 or the corresponding detectors 20 are arranged up to a maximum distance 56 of approximately 15 to 30 mm from the first area 16 .

As can be seen in particular from FIG. 3, the two signals 42 , 44 detected by paired surface areas 22 or by the corresponding detectors 20 are each fed to the two inputs of a differential amplifier 46 . This measure is also advantageously used in the exemplary embodiments in FIGS. 1 and 2, in which case corresponding pairs 36 of detectors are then connected to a differential amplifier 46 . The signals from the detectors 20 are subjected, among other things, to an adaptive filter function 52 and a cepstrum analysis function 78 ( FIG. 5).

The entire device, with the exception of a processor 54 , that is to say the light source 14 , the detectors 20 and the electronic components, such as, if appropriate, preamplifier 48 , differential amplifier 46 and analog / digital converter 50 are accommodated together in a measuring head 58 which is flat on the tissue 12 or the skin 18 can be placed. The measuring head 58 thus only has a connection by means of electrical conductors to the evaluation unit, in particular the processor 54 . The inside of the measuring head is filled with a filling compound 62 .

In a departure from the arrangement of the detectors 20 of the embodiments of FIGS. 1 and 2, the embodiment according to FIG. 3 has further surface areas 22 or associated detectors 20 , which are generally symmetrical on both sides on a straight line 40 running through the first area 16 and in pairs of the first region 16 are arranged.

The adaptive filter function 52 in FIG. 4 has two channels 70 , 72 , the first channel 70 carrying the unchanged input signal, but a delay stage 74 being switched on in the channel 72 . By means of the adaptation stage 76 , the filter coefficients are changed until the difference between the unfiltered input signal of the channel 70 and the filtered signal of the channel 72 becomes minimal on a quadratic average.

Referring to FIG. 5, which represents a block diagram of the cepstrum analysis function 78, the signals as time-amplitude function shown graphically and with a real-valued fast Hartley transformation (FHT) or a Fast Fourier Transform (FFT) or other Frequency analysis algorithm broken down into a power spectrum 88 or power spectrum. Here, the partial frequencies contained in the beat frequency are analyzed with regard to their intensity and bandwidth. The performance spectrum 88 is determined in real time with a number of support points greater than 64 points and is graphically prepared for each A / D converter channel 82 in a type of "waterfall display". This power spectrum is subjected to a moment analysis for both the intensity and the frequency. The moments thus formed can be combined into a vector and represented graphically. Overall, the cepstrum analysis function 78 consists of the series connection of a filter function 80 , an A / D converter 82 , a discrete time window 84 , a fast Fourier transform 86 , a power spectrum 88 , a logarithmic function 90 , an inverse fast Fourier transform 92 , a lifter function 94 , a fast Fourier transformation 96 and finally the modified power spectrum 89 . This latter process is also referred to as cepstrum analysis function 78 , whereby characteristic, changing frequencies can be made visible. The importance of the cepstrum analysis function is in particular that spectra with periodic fluctuations can be subjected to an exact analysis. The cepstrum is formed from the phaseless range of services.

All measurement data, evaluations and analyzes can be on one graphical user interface visualized and archived for further processing on mass storage devices. The different signals of the individual channels can also continuing with a cross-correlation, the autocorrelation and other signal evaluation algorithms compared and be evaluated.

The embodiment of FIGS. 1 and 2 works as follows. A semiconductor laser arranged in the measuring head 58 radiates coherent, monochromatic light, in particular a coherence length greater than 10 cm, directly into the optical fiber piece 24 . The light is transmitted in the optical fiber piece 24 to the surface of the skin 18 in the first region 16 . The optical fiber piece 24 should preferably be a mono-mode fiber with a minimum diameter of approximately 300 μm in order to be able to transmit the light output of the semiconductor laser. Depending on the design, the optical fiber piece 24 can be dispensed with if the laser light is focused directly on the skin surface with the aid of collimation optics 26 . The remitted light is received on the optical fibers 28 in the further surface areas 22 and passed on to the photodiodes 30 . Absorption filters 34 and polarization filters 32 are located in front of or behind the optical fibers 28 and / or in front of the optical fiber piece 24 .

All fibers and filters are preferably locked in an opaque plastic or ceramic socket on the measuring head 58 . The fibers are arranged in pairs off-center of a longitudinal axis 100 on a carrier plate of the measuring head 58 . The distance between the individual pairs 36 is the same, and this distance can be made variable in different versions. The optical fibers 28 should not exceed a diameter of 400 μm, since the signal-to-noise ratio becomes better as the diameter becomes smaller. However, the intensity of the measurement signal also decreases as the diameter becomes smaller, so that a compromise can be found here. When choosing the photodiodes 30 , it should preferably be ensured that the individual photocurrents differ only slightly from one another with the same illumination. The entire evaluation electronics consisting of preamplifier 48 and differential amplifier 46 is integrated in the shielded housing of the measuring head 58 . The analog / digital converter 50 can also be arranged in the measuring head 58 . However, there is also the possibility of placing these components outside the measuring head 58 on a measuring card, so that only digitized signals are passed on to the processor 54 . The evaluation electronics have the task of converting and amplifying the current coming from the photodiodes 30 into a voltage, which is carried out by means of the preamplifier 48 . A signal difference is then formed by paired and switched photodiodes 30 by means of the differential amplifier 46 and further amplified. Finally, each differential amplifier 46 is followed by an analog / digital converter 50 with 12 to 16 bit resolution and a minimum sampling rate of approximately 20 kHz. An A / D converter channel is thus assigned to each pair 36 of the photodiodes. The digitized signals are sent to processor 54 for evaluation.

It remains to be mentioned that, in contrast to the embodiment of FIGS. 1 and 2 in the exemplary embodiment according to FIG. 3, the pairs 36 of the photodiodes 30 and the surface areas 22 are not arranged in pairs next to one another, but rather, so to speak, diametrically and symmetrically to the left and right of the first region 16 are formed. With this arrangement too, improved signal-to-noise ratios can be formed by forming the difference between the output signals of corresponding pairs 36 of photodiodes 30 . However, this arrangement can be somewhat disadvantageous, particularly in the presence of a preferred direction of light propagation in the tissue.

In this respect, the illustrated embodiments of FIGS. 1 and 2 with regard to the paired arrangement of the photodiodes 30 or further surface areas 22 are a preferred embodiment of the invention.

Reference list

10th

- Contraption

12th

- tissue

14

- light source

16

- first area

18th

- Skin

20th

- detector

22

- area

24th

- Optical fiber piece

26

- collimation optics

28

- optical fiber

30th

- photodiode

32

- polarization filter

34

- absorption filter

36

- Pair

38

- Line

40

- Straight

42

- signal

44

- signal

46

- differential amplifier

48

- preamplifier

50

- A / D converter

52

- filter function

54

- processor

56

- distance

58

- measuring head

60

- Ladder

62

- filling compound

64

- depth of penetration

66

- photon path

68

- photon path

70

- Channel

72

- Channel

74

- delay stage

76

- adaptation level

78

- Cepstrum analysis function

80

- filter function

82

- A / D converter

84

- Time window

86

- Fast Fourier transform

88

- Range of services

90

- Logarithmic function

92

- inverse Fast Fourier transform

94

- lifter function

96

- Fast Fourier transform

98

- mod. Range of services

100

- longitudinal axis

Claims (14)

1. A method for detecting the blood flow and / or the flow of intracorporeally flowing liquids in human or animal tissue ( 12 ), characterized in that photons of a coherent, monochromatic light source ( 14 ) into the tissue ( 12 ) through a first region ( 16 ) can occur, photons emerging from the tissue ( 12 ) with respect to frequency and number are detected at different distances from this first region ( 16 ) and from the information, namely frequency and / or number and / or location of the again emerging photons by means of an evaluation program and / or algorithm draws conclusions about relative changes in the flow rate and / or speed and / or spatial position of the blood flow and / or the flow of intracorporeally flowing liquids in the tissue ( 12 ). 2. The method according to claim 1, characterized in that one uses a light source ( 14 ) with a coherence length greater than 10 cm, and one at a certain distance from the first region ( 16 ) again emerging photons, preferably at the same time at least in two surface areas ( 22 ) closely adjacent or arranged symmetrically to the first area ( 16 ) are detected. 3. The method according to claim 2, characterized in that the detected signals each two surface areas ( 22 ), among other things, a differential amplifier function ( 46 ) is supplied. 4. The method according to claim 2 or 3, characterized in that the detected signals are subjected, inter alia, to an adaptive filter function ( 52 ) and / or a cepstrum analysis function ( 78 ). 5. Device ( 10 ) for detecting the blood flow and / or the flow of intracorporeally flowing liquids in human or animal tissue ( 12 ) with a coherent, monochromatic light source ( 14 ), in particular a laser, for emitting photons into the tissue ( 12 ) by a locally well-defined first region (16) of the fabric (12) covering the skin, if necessary, (18) and having a plurality of detectors (20) for detecting the out of further surface regions (22) of the skin (18) and the fabric (12 ) again emerging photons, the further surface areas ( 22 ) being spaced at different distances from the first area ( 16 ), characterized in that the further surface areas ( 22 ) or the associated detectors ( 20 ) are adjacent to one another in pairs and approximately in series ( 38 ) are arranged lying one behind the other, each pair ( 36 ) being at a different distance from the first region ( 16 ), the distances being adjacent beard pairs ( 36 ) are, in particular, equidistant and the blood flow and / or the flow of intracorporeally flowing liquids in the tissue ( 12 ) is detected as the measured variable. 6. The device according to claim 5, characterized in that the light source ( 14 ) at least one of the tissue ( 12 ) can be applied or attached to the front face of the optical fiber piece ( 24 ) or a collimation lens ( 26 ) for focusing the laser light on the tissue ( 12 ) or is subordinate to the skin ( 18 ). 7. Device according to one of claims 5 or 6, characterized in that the detectors ( 20 ) each have a fabric ( 42 ) on the front side attachable or attachable optical fiber ( 28 ), which is followed by a photodiode ( 30 ). 8. Device according to one of the preceding claims 5 to 7, characterized in that a polarization filter ( 32 ) downstream of the light source ( 14 ) and the detectors ( 20 ) is connected upstream. 9. Device according to one of the preceding claims 5 to 8, characterized in that the detectors ( 20 ) is assigned an absorption filter ( 34 ). 10. Device according to one of claims 5 to 9, characterized in that the wavelength of the light source ( 14 ), which is preferably in the form of a semiconductor laser, is in the range from 600 nm to approximately 1200 nm, preferably approximately 820 nm. 11. Device according to one of the preceding claims 5 to 10, characterized in that the further surface areas ( 22 ) or the corresponding detectors ( 20 ) up to a maximum distance ( 56 ) of about 15 mm to 30 mm from the first area ( 16 ) are arranged. 12. Device according to one of the preceding claims 5 to 11, characterized in that the two signals ( 42 , 44 ) detected by paired surface areas ( 22 ) are each fed to the two inputs of a differential amplifier ( 46 ). 13. Device according to one of the preceding claims 5 to 12, characterized in that the light source ( 14 ) and the detectors ( 20 ) and electronic components, such as. Preamplifier ( 48 ), differential amplifier ( 46 ) and / or analog / digital Transducers ( 50 ) are arranged together in a measuring head ( 58 ) which can be placed flat on the tissue ( 12 ) or the skin ( 18 ), the measuring head ( 58 ) being connected to the evaluation unit only by means of electrical conductors ( 60 ), in particular a processor ( 54 ). 14. Use of a device ( 10 ) for detecting the blood flow and / or the flow of intracorporeally flowing liquids in human or animal tissue ( 12 ) with a coherent, monochromatic light source ( 14 ), in particular a laser, for emitting photons into the tissue ( 12 ) by means of a locally well-defined first area ( 16 ) of the skin ( 18 ) possibly covering the tissue ( 12 ) and with several detectors ( 20 ) for detecting the areas ( 22 ) of the skin ( 18 ) or of the tissue ( 12 ) again emerging photons, the further surface areas ( 22 ) being spaced apart from the first area ( 16 ) at different distances.