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United States Patent |
6,230,044
|
Afanassieva
,   et al.
|
May 8, 2001
|
Apparatus and method for spectroscopic analysis of human or animal tissue
or body fluids
Abstract
The present invention relates to methods employing fiberoptic evanescent
wave Fourier transform infrared (FEW-FTIR) spectroscopy using fiberoptic
sensors operated in the attenuated total reflection (ATR) regime in the
middle infrared (MIR) region of the spectrum (850 to 4000 cm.sup.-1). The
apparatus and method claimed is applied to diagnostics and
characterization of noninvasive and rapid (seconds) direct measurements of
spectra (in real time) of normal and pathological tissues in vivo, ex vivo
and in vitro. The aim of our invention is testing and monitoring of normal
skin and various skin tumor tissues at the early stages of their
development Furthermore the apparatus and method is suitable for fluid
diagnostics, as well as endoscopic and biopsy applications. Specifically
the remote diagnostics of normal skin and malignant tissue on the skin
surface (directly on patient) can distinguish between normal and malignant
skin. In addition the apparatus and method can be applied for different
types of clinical diagnostics. Finally the invention relates to
diagnostics of environmental damage of skin tissue and acupuncture points,
and treatment of skin tissue on a molecular level.
Inventors:
|
Afanassieva; Natalia I. (709 Putnam Dr., Reno, NV 89503);
Bruch; Reinhard Frank (709 Putnam Dr., Reno, NV 89503)
|
Appl. No.:
|
172186 |
Filed:
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October 13, 1998 |
Intern'l Class: |
A61B 006/00 |
Field of Search: |
600/473,475,476
|
References Cited
U.S. Patent Documents
5313941 | May., 1994 | Braig et al. | 600/322.
|
5997472 | Dec., 1999 | Bonnell et al. | 600/473.
|
6016440 | Jan., 2000 | Simon et al. | 600/473.
|
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Hartman; Charles
Parent Case Text
This application claims benefit to provisional application 60/063,054 filed
on Oct. 27, 1997.
Claims
We claim:
1. An apparatus for spectroscopic analysis of human or animal tissue or
body fluids, said apparatus comprising:
a radiation source for generating radiation in the middle infrared region
in the spectral range from 3.mu. to 20.mu.,
at least one ultra sensitive fiber optical probe adapted to be brought in
direct contact with said tissue or body fluid and operated in the
attenuated total reflection (ATR) mode,
a detector for detecting radiation reflected from said tissue or body
fluid, and
a Fourier transform infrared spectrometer receiving signals from said
detector and operated in said middle infrared region.
2. An apparatus according to claim 1, comprising a plurality of
interchangeable fiber-optical probes.
3. An apparatus according to claim 1, characterized in that said apparatus
is adapted to directly measure IR-spectra in real time.
4. An apparatus according to claim 1, comprising means for storing
spectroscopic reference data representative for tissue or fluid of a first
type and for storing spectroscopic data representative for tissue or fluid
of a second type which is to be analyzed.
5. An apparatus according to claim 4, comprising means for comparing said
spectroscopic reference data and said spectroscopic data.
6. An apparatus according to claim 1, comprising means for selecting
pre-given wavelength ranges in which said spectrometer operates.
7. An apparatus according to claim 1, wherein said probe is adapted to
measure living tissue or fluid in vivo.
8. An apparatus according to claim 1, wherein said Fourier transform
spectrometer measures spectroscopic data of said tissue on a molecular
level.
9. An apparatus according to claim 1, wherein said Fourier transform
spectrometer is operated as a fiberoptic evanescent wave spectrometer.
10. An apparatus according to claim 1, wherein said probe is adapted to
percutaneous analysis of tissue or body fluids.
11. A method for spectroscopically analyzing human or animal tissue or body
fluids, said method comprising:
generating radiation in the middle infrared region in the spectral range
from 3.mu. to 20.mu.,
providing at least one ultra sensitive fiber optical probe (27) and
bringing said probe in direct contact with said tissue or body fluid and
operating the probe in the attenuated total reflection mode (ATR),
detecting radiation reflected from said tissue or body fluid, and
providing a Fourier transform infrared spectrometer receiving detected
signals and operating said spectrometer in said middle infrared region.
12. The method of claim 11, comprising the step of directly measuring
IR-spectra in real time.
13. The method of claim 11, comprising the step of storing spectroscopic
reference data representative for tissue or fluid of a first type and
storing spectroscopic data representative for tissue or fluid of a second
type which is to be analyzed.
14. The method of claim 13, comprising the step of comparing said
spectroscopic reference data and said spectroscopic data.
15. The method of claim 11, comprising the step of selecting pre-given
wavelength ranges and operating said spectrometer in said wavelength
ranges.
16. The method of claim 11, comprising the step of measuring living tissue
or fluid in vivo.
17. The method of claim 11, comprising the step of measuring spectroscopic
data of said tissue or fluid on a molecular level.
18. The method of claim 11, comprising the step of operating said Fourier
transform spectrometer as a fiberoptic evanescent wave spectrometer.
19. The method of claim 11, comprising the step of measuring percutaneously
tissue or body fluids.
Description
BACKGROUND PRIOR ART
Fourier transform infrared (FTIR) spectroscopy monitoring techniques have
been discussed, for example in Bornstein et al. U.S. Pat. No. 5,070,243,
and Bornstein and Lowry U.S. Pat. No. 5,436,454. In the U.S. Pat. No.
5,070,243 Bornstein et al. claim unclad optical waveguides as probes for
fluid medium to increase the sensitivity of spectroscopic measurements by
the ATR method. However, the sensors and waveguides claimed are not
suitable for tissue diagnostics in vivo. In the U.S. Pat. No. 5,436,454
(1995) Bornstein and Lowry describe another optical probe for remote
attenuated total reflectance measurements of liquid, and/or relatively
solid materials. Their fiber probes are quite rigid and are characterized
by a waveguide element in the form of a loop. In addition, chalcogenide
glass is used as the fiber material. These suggested probes are not very
practicable for nontoxic, noninvasive tissue diagnostics in vivo.
Furthermore the epoxy used for material sealing and the chalcogenide glass
as a fiber probe may be toxic and therefore not suitable for tissue
diagnostics in vivo. Stevenson et al., in U.S. Pat. No. 5,585,634 (1996)
claims attenuated total reflectance sensing with U shaped probes
consisting of optical fibers with core cladding, where only the U shaped
sensor surface portion is uncladded. This method is limited by the
selection of fiber material (chalcogenide glass) and the complex shape of
the fiber probe, and requires extended sensing time. In addition,
Stevenson does not claim any tissue applications in vivo.
Weissman et al., U.S. Pat. No. 5,569,923 discloses a fiber optic
reflectance probe for the FTIR and ATR regime. The probe is made of
chalcogenide glass and has not been optimized for tissue diagnostics in
vivo. Devices and methods for optical and spectroscopic methods for tissue
diagnostics or analysis of biological materials are described in U.S. Pat.
Nos. 5,280,788, and 5,349,954. In particular the invention of James et al.
U.S. Pat. No. 5,280,788 relates to optical spectroscopy in the diagnosis
of tissue where a needle probe is in close contact with the tissue
surface. However this method utilizes dye lasers as a light source and is
therefore not very convenient for clinical applications. The U.S. Pat. No.
5,349,954 by Tiemann et al. proposes an instrument for characterizing
tumor tissue, specifically mammographically abnormal tissue, with a broad
band light source and monochromator. This cancer diagnostic technique uses
a hollow needle, fiber optic illuminator for breast tissue detection. This
method can only analyze shifts in hemoglobin oxygenation. Evans suggests
in U.S. Pat. No. 5,419,321 a non-invasive medical sensor for living tissue
such as skin tissue or organs, where the noninvasive monitoring process is
not specified in detail. This patent is based on the non-invasive
determination of analyte concentration in the bodies of mammals, in
particular the concentration of glucose in blood. Stoddart and Lewis in
U.S. Pat. No. 5,349,961 disclose a methodology and apparatus for the
clinical evaluation of biological matter, related to internal tissue
characterization of skin pigmentation, on a nonintrusive in vivo basis.
The examination and/or analysis of tissue and/or biological materials is
performed by optical spectrometry in the visible and near infrared range,
which do not provide molecular vibrational band information.
BACKGROUND OF THE INVENTION
This invention is concerned with a new combination of Fourier Transform
Infrared (FTIR) Spectroscopy and fiber optics technology in the middle
infrared region from about 3 to 20 microns. Furthermore this invention
relates to the diagnostics of normal and pathological tissues in vivo. In
particular nontoxic, chemically inert, nonhygroscopic, intrinsically safe,
flexible, low loss optical fiber probes are used for noninvasive or
minimally invasive, fast, direct, remote measurements of infrared spectra
from tissue in vivo.
The present invention relates to a new complex spectroscopic method and
applications using middle infrared optical fiber probes for noninvasive
diagnostics of normal, precancerous, and cancerous human tissue in vivo as
well as other biological tissues and/or fluids at a molecular level.
The present invention elucidates new trends and methods of noninvasive
diagnostics of biotissues in vivo, where more advanced technologies are
combined including fiberoptic evanescent wave Fourier transform infrared
(FEW-FTIR) spectroscopy tools using extremely low loss fibers with
different configurations of fiber optical probes and sensors operated in
the ATR regime in the middle infrared (MIR) wavelength range (800 to 4000
cm.sup.-1). In particular these methods have the following unique
properties: nondestructive, noninvasive, nontoxic, chemically inert,
intrinsically safe, nonhygroscopic, fast (seconds), direct, remote,
realtime, in vivo, ex vivo and in vitro tissue diagnosis. These techniques
are simple and are characterized by low-cost maintenance and are therefore
suitable to any commercial application of FEW-FTIR spectrometer including
clinical applications.
In particular the potential of the method of this invention is huge for
characterizing normal and pathological tissue of the human or animal body
(see FIG. 1 and 2). Hence this combination of fiber optical sensors and FT
spectrometers can be applied to many fields: (i) noninvasive medical
diagnostics of cancer and other disease states in vivo, (ii) monitoring of
biochemical processes, (iii) surface diagnostics of numerous materials,
(iv) minimally invasive bulk diagnostics of tissues and materials, (v)
characterization of the quality of food, pharmacological products and
cosmetics (vi) characterization and treatment of aging of the skin, etc.
This invention is concerned with bare-core (unclad) fibers used in
different configurations of probes in the ATR regime of FTIR spectroscopy
for spectroscopic monitoring and diagnostics in real time of skin tissue
in vivo, ex vivo and in incisions (see FIG. 6). The invention includes
also nontoxic, minimally invasive, remote, fast, and ex vivo
characterization of normal and abnormal tissue from breast, stomach, lung,
prostate, kidney and other body parts during surgery, allowing an
alternative first step of spectral histopathological examination and
disease state characterization. This technique can open another branch of
clinical diagnostics concerned with minimally invasive, fast, remote
analysis for endoscopic and catheter applications as well as for the
needle regime. Using these techniques, a high sensitivity for the
composition of body fluids such as blood, saliva, urine, lymph and gland
system is achieved as well.
This invention relates primarily to diagnostics of normal and pathological
human skin tissue in vivo, where the sensor probe has direct contact with
the patients skin tissue. As an example of this approach, we can
distinguish and diagnose healthy, tumorous, precancerous and cancerous
tissue of the skin on a molecular level in specific IR spectral ranges
(fingerprint regions).
The invention provides a powerfill method to detect functional molecular
groups to elucidate complex structures within tissue, to characterize,
distinguish and diagnose healthy, tumorous, precancerous and cancerous
tissue at an early stage of development. More particularly, the invention
provides important information such as the absorbance measured as a peak
position, peak height, peak height ratio, peak area or peak area ratio
from the obtained FTIR tissue spectra.
In a broad sense, the invention is also directed to a new method and
compact apparatus with several fiber optical probes and accessories for
obtaining response data by examining biological tissue under the influence
of the environment, for example sun-induced aging of the human skin or
treatment for aging skin and diagnostics of acupuncture points and normal
human skin zones.
SUMMARY OF THE INVENTION
The subject of the present invention is noninvasive tissue diagnostics in
vivo using a combination of FTIR spectroscopy method with fiber optical
techniques. In accordance with the present invention unclad optical fibers
and fiber probes in the regime of ATR are applied to living tissue of
animals and humans. A beam of infrared radiation (preferably middle
infrared radiation) is passed through a low loss optical fiber and
interacts with the tissue via the ATR effect. In this process, the
absorbing tissue is placed in direct contact with the reflecting fiber.
The length of interaction of the tissue surface with a cylindrical flexible
fiber probe varies from about 1 to 10 mm. The depth of penetration of the
infrared light in living tissue is of the order of the wavelength used.
Silver halide fibers are characterized by an index of refraction n.sub.1
of approximately 2.2 whereas living tissue has an index of refraction
close to water with n.sub.2 =1.3. Therefore the ATR condition n.sub.1
>n.sub.2 is satisfied and the and the multiply reflected wave can be
detected and analyzed by a FT spectrometer. In the case of very small
biopsy samples the flexible fiber probe can be bent at specific angles. In
addition, infrared needle probes of the present invention can be used for
fluid and tissue diagnostics, in particular for minimally invasive biopsy
techniques. Furthermore this invention includes compact fiber optic probes
for endoscopic and/or catheter applications. For example the needle probes
are also suitable for investigations of breast cancer and prostate cancer.
Moreover, this regime of minimal invasive biopsies has a great potential
for body fluid analysis.
The optical fiber elements for ATR probes are commonly polycrystalline
AgBr.sub.x Cl.sub.l-x (where x=0 to 1) fibers, typically 1 mm in diameter.
They operate in the spectral range 3 to 20 .mu.m with low optical losses,
typically 0.1 to 0.5 dB/m at 10 .mu.m. A preferred fiber probe is
characterized by a high flexibility (R.sub.bending> 10 to 100 fiber
diameters) depending on the concentration of bromine and chlorine,
structure, purity of composition and manufacturing process. These type of
infrared fibers are soft, nontoxic and nonhygroscopic. The optical system
consists of the optical fibers to input and output the infrared radiation
and focusing spherical mirrors or lenses to focus an infrared beam into
the fiber and collect light from the fiber onto a cooled detector
(preferably a nitrogen cooled MCT detector). The optical scheme of the
invention is specifically designed and applicable with any commercial FT
spectrometer.
The fiberoptic evanescent wave Fourier transform (FEW-FTIR) spectra
measured in vivo enable the user to select specific spectral ranges, where
fundamental changes in the protein, lipid, phosphate, and sugar systems as
well as hydrogen bonds occur. Such FEW-FTIR spectra reveal important
information about "order-disorder" phenomena in living tissue and hence
the disease state.
A preferred embodiment involves ATR fiber optical probes for fast, remote
(up to 3 m), noninvasive and nontoxic diagnostics of skin cancer in vivo
and ex vivo during surgery and following incisions.
Another preferred embodiment is the measurement and disease state
characterization of human skin tissue in vivo in the spectral range from
800 to 3700 cm.sup.-1. Specifically the spectral variation from normal to
pathological tissues is indicated in the regions of 800 to 1500,
1500-1800, 2700-3100, and 3100 to 3700 cm.sup.-1. The group of bands
between 800 and 1500 originate mainly from molecular vibrations of sugars,
phosphate groups, and amide III. The spectra obtained in the 1500 to 1800
cm.sup.-1 wavenumber region stem from amide I, amide II, and two resolved
carbonyl bands. The range from 2700 to 3100 cm.sup.-1 is dominated by C--H
symmetric and asymmetric stretching vibrations. Bands arising from amide A
(O--H and N--H vibrations) occur in spectral region from 3100 to 3700
cm.sup.-1 (Anthony R. Rees and Michael J. E.
Steinberg, From Cells to Atoms, Blackwell Scientific Publications, Oxford
(1994)).
A further preferred embodiment is the analysis and means for analyzing the
pronounced variation of these specific bands from normal, precancerous, to
cancerous skin tissue measured in vivo. In particular this diagnostic
method is very sensitive to diagnose early stages of skin cancer and
precancerous phenomena. Benign and non-benign tumors can be clearly
differentiated by the FTIR method. This type of skin diagnostics is ideal
for surface investigations because the depth of IR light penetration is
about 10 to 20 .mu.m depending on the wavelength. The method can also be
applied to skin aging involving changes of both intrinsic aging and
sun-induced aging (photoaging or dermatoheliosis).
Another preferred embodiment is the diagnostics of normal skin tissue,
including the surface response from different acupuncture points and skin
zones of the human body. This method is a more selective technique on a
molecular level when compared to traditional acupuncture diagnostics, such
as electroacupuncture.
In summary the FEW-FTIR spectroscopy technique using fiber optical sensors
provides a new effective, fast method for characterization of normal,
cancerous, and otherwise diseased skin tissue. The changes in tumor
spectra can be observed in real time and analyzed by state of the art
pattern recognition and neural network computer programs. Finally the
method is very sensitive to the influence of the environment on skin
tissue damage. Another advantage of this method is potential applications
to any environment related health problems.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a schematic illustration of a preferred embodiment of the
diagnostics method of the present invention
FIG. 2 is a block diagram showing the principle of tissue diagnostics using
the present invention
FIG. 3, parts a, b and c are schematic views of different middle infrared
(MIR) fiber probe embodiments of the present invention
FIG. 3, part d is a schematic view of an endoscope or catheter embodiment
of the present invention
FIG. 4 is a remote FEW-FTIR spectrum of normal skin measured in vivo. The
measurement time is about 40 seconds.
FIGS. 5a to 5d show typical FEW-FTIR spectra of normal human skin tissue in
vivo in the practice of this invention. The dotted lines represent
computer fits of the main observed band structures. Lorentzian profiles
have been used as fitting finctions. The spectra originated from remote
measurements.
FIG. 6, parts a, b, and c are schematic diagrams of methods for normal and
cancer tissue diagnosis in accordance with the invention.
a.) in vivo
b.) ex vivo
c.) incision (under epidermis)
FIG. 7 shows several in vivo FEW-FTIR spectra of "normal" human skin close
to a benign tumor produced by the method of the present invention.
FIG. 8 shows several in vivo FEW-FTIR spectra of a pigment nevus
(noncancerous) in vivo for several patients, produced by the method of the
present invention.
FIG. 9a displays in vivo measurements of FEW-FTIR spectra of normal (A) and
malignant (B) skin tissues (premelanoma case) in the range of 1480-1850
cm.sup.-1 . The spectra were recorded using the method of the present
invention.
FIG. 9b shows ex vivo measurements of FEW-FTIR spectra of normal (A) and
malignant (B) skin tissues (premelanoma case) in the range of 1480-1850
cm.sup.-1. The spectra were recorded using the method of the present
invention.
FIG. 10a indicates in vivo measurements of FEW-FTIR spectra of normal (A)
and malignant (B) skin tissues (melanoma case) in the range of 1480-1850
cm.sup.-1. The spectra were recorded using the method of the present
invention.
FIG. 10b represents ex vivo measurements of FEW-FTIR spectra of normal (A)
and malignant (B) skin tissues (melanoma case) in the range of 1480-1850
cm.sup.-1. The spectra were recorded using the method of the present
invention.
FIG. 11 shows in vivo measurements of FEW-FTIR spectra of normal (A) and
malignant (B) skin tissues (basaloma case) in the range of 1480-1850
cm.sup.-1. The spectra were recorded using the method of the present
invention.
FIG. 12a shows in vivo measurements of FEW-FTIR spectra of normal human
skin in the range of 850-1800 cm.sup.-1 for three different body
locations, namely the left elbow crease (LU5), lower lip and left ear. The
spectra were recorded using the method of the present invention.
FIG. 12b indicates in vivo measurement of FEW-FTIR spectra of normal human
skin in the range of 2450-4000 cm.sup.-1 for three different body
locations, namely the left elbow crease (LU5), lower lip and left ear. The
spectra were recorded using the method of the present invention.
FIG. 13a shows in vivo measurements of FEW-FTIR spectra of normal human
skin in the range of 850-1800 cm.sup.-1 for two acupuncture points of the
left wrist. The spectra were recorded using the method of the present
invention.
FIG. 13b represents in vivo measurements of FEW-FTIR spectra of normal
human skin in the range of 2450-4200 cm.sup.-1 for two acupuncture points
of the left wrist. The spectra were recorded using the method of the
present invention.
FIGS. 14a-e indicate in vivo measurements of FEW-FTIR spectra of normal
skin in the range of 1500-1800 cm.sup.-1 for five different acupuncture
points: a)lower lip, b) left ear, c) elbow crease (LU5), d) left wrist
(8p), and e) lower wrist (9p). The spectra were recorded using the method
of the present invention.
FIGS. 15a-e show in vivo measurements of FEW-FTIR spectra of normal skin in
the range of 2800-3000 cm.sup.-1 for five different acupuncture points:
a)lower lip, b) left ear, c) elbow crease (LU5), d) left wrist (8p), and
e) lower wrist (9p). The spectra were recorded using the method of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
With reference to the diagrammatic view of FIG. 1, illustrating noninvasive
diagnostics of tissue and fluids in vivo 10, this method is connected to
the field of optical spectroscopy 11, and in particular to Fourier
Transform techniques 12 in combination with fiber optics and sensors 13.
Tissue measurements are performed in the middle infrared (MIR) 14, and
recorded spectra are fingerprints for specific molecular vibrations 15.
Specialized MIR fibers of the type AgBr.sub.x Cl.sub.1-x 16, operated in
the range 3-20 .mu.m with a diameter D<=1 mm 17 and extremely low losses
18 have unique properties such as high flexibility and softness, and are
nontoxic and nonhygroscopic 19. The unclad MIR fibers 16 are designed for
the attenuated total reflection (ATR) regime 20. Fiber probe 21 is in
direct contact with the tissue 22.
The general nature and usage of the apparatus in accordance with the
invention is illustrated in FIG. 2. The optical scheme consists of a
commercial FTIR spectrometer 23. Light from an IR source 24 passes through
a Michelson interferometer setup 25, and is for example extracted through
an external port and focused into an unclad optical fiber. The optical
scheme of this invention consists of optical fibers and fiber probe 27 to
input and output the infrared radiation via focusing lenses or spherical
mirrors 26,29. In accordance with the invention the unclad fiber probe is
in direct contact with the tissue sample 28, where the length of contact
between the fiber and tissue varies from one to a few millimeters. In
accordance with this invention the unclad fiber has direct contact with
the tissue similar to the prism in the ATR method.
At the tissue-fiber interface, an evanescent wave penetrates beyond the
tissue surface into the sample. An evanescent wave is characterized by a
nonpropagating field in the optically denser medium, whose electric field
amplitude decays exponentially with distance from the surface. The
reflected light is collected from the tissue-fiber interface onto a
detector, preferably a nitrogen-cooled MCT (Mercury, Cadmium, Tellurium)
detector 30. After amplification the signal is processed in a
microprocessor or computer system 31. It is further noted that a larger
tissue-fiber contact corresponds to a more pronounced FTIR tissue
spectrum. Depending on the signal to noise ratio an optimal number of
scans can be chosen for in vivo tissue measurements. Typical recording
times range approximately from 2 to 40 seconds. Therefore this diagnostic
technique is very convenient for human patient and animal testing.
A schematic view of different fiber probes in close contact with the tissue
are depicted in FIG. 3, parts a to 3d. An embodiment of these probes is
that the fibers, preferably silver halide fibers, can be bent to a
specific form and angle creating different tip probes depending on the
size of the tissue samples. The probes of this invention can be utilized
with different radii of curvature of the tip portion. In FIG. 3, part a is
shown an unclad MR fiber tip probe 32 covering a larger tissue segment 33.
Another exemplary utilization of the tip probe is indicated in FIG. 3,
part b. Here the MIR fiber 34 is bent at a sharp angle, forming a tip
probe for detection of smaller areas of tissue 35. This probe is suitable
for detection of normal and malignant tissues with size of the order of 1
mm or less. Such small tip probes, typically 1 mm in diameter, can also be
used for biopsies. Another embodiment of the probe is shown in FIG. 3,
part c, wherein a needle tip 36 touches a tissue surface 37. This probe of
the present invention is used in minimally invasive diagnostics, for
example for breast cancer. The same probe can be used as well in
measurements of fluids. A further embodiment of our invention of the probe
38 touching the tissue 41 is shown in FIG. 3, part d, wherein an endoscope
or catheter 39 is illustrated with additional remote fiber cable 40.
This type of sensor in accordance with the invention can be applied for
breast, kidney, stomach, lung, and prostate cancer diagnostics. The fiber
probes shown in FIG. 3, parts a to d are easily changed and are generally
used only one time. For fluid examination the fiber probe is located
within the hypodermic needle or syringe. In this invention changeable tip
probes are used for biopsy and endoscopic applications. The special tip
size and configuration allow the collection or scattering of IR light for
different type of tissue examinations. In another embodiment (see FIG. 4)
a typical remote FEW-FTIR spectrum of normal skin in vivo in the range of
about 500 to 4500 cm.sup.-1 is displayed. In this spectrum the absorbance
is plotted versus the wavenumber in cm.sup.-1 and the spectrum is measured
with a resolution of 4 cm.sup.-1.
Polycrystalline silver halide AgBr.sub.x Cl.sub.1-x fibers, preferably with
1 mm diameter, extremely low optical losses (0.1 to 0.5 dB/m in the region
of 10 .mu.m), and high flexibility (Rbending>10 to 100 fiber diameters)
are used as fiber tip probes (Artjushenko et al. , U.S. Pat. No. 5,309,543
and U.S. Pat. No. 5,342,022, and Kupper and Butvina, Offenlegungschrift DE
4414552A1). As can be seen from FIG. 4, the fiber probes transmit IR
radiation with low losses in the range of about 800 to 4000 cm.sup.-1,
Hence, in accordance with one aspect of the invention the quality of the
obtained IR. spectra is high, i.e. low background, excellent statistics
and full compensation in the region of water vapor and CO.sub.2
vibrations.
Another embodiment of the human skin diagnostic in vivo is related to
different fingerprint regions of the IR spectra in the wavenumber ranges
800 to 1500 cm.sup.-1, 1500 to 1800 cm.sup.-1, 2700 to 3100 cm.sup.-1, and
3100 to 3700 cm.sup.-1. In the present invention, the FEW-FTIR method of
tissue diagnostics in the above ranges of spectral measurements can be
extended to the near infrared (NIR) of far infrared (FIR) regions using
different fiber materials and fiber probes.
The present invention is further embodied in the in vivo FEW-FTIR spectral
features of normal human skin tissue shown in FIGS. 5a to 5d. FIG. 5a
indicates the significant IR bands of 42 to 49 connected with vibrations
in systems of phosphate groups, sugars, amide III and CH.sub.2
deformations. In particular, in accordance with the invention peaks 42 and
43 belong to vibrations of the C--O--C groups in sugars. Peak 44 is
attributed to symmetric stretching modes of phosphate groups
(PO.sub.2.sup.--). Furthermore peak 45 coincides with stretching
vibrations of C--O and C--C bands in systems of sugars. The structure
labeled 46 originates from asymmetric stretching of phosphate groups
(PO.sub.2.sup.13) plus associated C--O--C bands in sulfoglycolipids,
whereas peak 47 stems from amide III band components of proteins. Peak 48
of this invention is due to symmetric stretching of carboxylate groups
(COO.sup.--) and finally peak 49 corresponds to the bending of methylene
(CH.sub.2). All of these band structures can be used as fingerprints for
tissue diagnostics, and are related to this invention. P As may be seen in
FIG. 5b, four main bands contribute to the FEW-FTIR spectrum of normal
skin tissue in the range of the dominant amide bands. Thus peak 51 is
associated with amide II vibration and peak 52 is due to amide I of a
helical structure for normal skin. In addition two weaker bands, 53 and
54, are assigned to C.dbd.O aliphatic and C.dbd.O cyclic groups,
respectively. In accordance with the present invention FIG. 5c shows three
major band structures, 5556 and 57. Bands 55 and 56 correspond to
symmetric and asymmetric stretching of methylene group (CH.sub.2) in
systems of fatty acids, and shoulder 57 of the band 56 is due to
asymmetric stretching of methyl group (CH.sub.3). All of these bands play
an important role in tissue diagnostics and are therefore an embodiment of
this invention.
Another embodiment of our invention is associated with the FEW-FTIR
spectrum of normal skin tissue in the range of about 3100 to 3700
cm.sup.-1. The band structure labeled 59 with shoulder 58 belong to NH
stretching modes in the amide A system of proteins, and the partially
resolved band 60 originates from OH stretching. The same FTIR-FEW approach
can be applied to tumor diagnostics and disease state characterization of
skin tissue. Therefore this invention relates also to cancer diagnostics
in early and advanced stages. FIG. 6, parts a, b, and c depict clinical
procedures for analyzing skin tissue material in vivo and ex vivo during
surgery, and in incisions (in vitro).
FIG. 6, part a indicates a sequence of measurements of human skin 61 in
vivo (directly on patient), where point 62 is the center of tumor or
cancer and the points 63 and 64 correspond to measurements taken in the
direction of normal skin. The distance between 62-63 and 62-64 depend on
the size and growth of the tumor tissue. FIG. 6, part b shows the scheme
of exvivo measurements at the surface off skin tissue 65 after surgery.
Here 66, 67 and 68 correspond to the same locations (62, 63 and 64)
indicated in FIG. 6, part a. Moreover FIG. 6, part c shows a
characteristic cut 69 at the center of a tumor 70 and distant points 71
and 72 to measure different layers of the tumor and normal skin below the
skin surface. Such experiments can be performed conveniently in any
surgical center (operating room) for ex vivo examinations during surgery.
This method applies to breast cancer and tumorous tissues from lung,
kidney, prostate, stomach, glands etc. for on-line, remote, fast,
nondestructive diagnostics. The results of such spectral measurements can
be compared directly with the traditional and more time consuming analysis
of histological data. This new IR spectral histology method in vitro is in
accordance with the present invention.
FIG. 7 demonstrates the sensitivity of FEW-FTIR non invasive measurements
of skin tissue in vivo. For example FTIR spectra of normal skin (A),
distant point (see FIG. 6, part a, point 63) exhibit four distinct bands
in the range of the main amide vibrations (see FIG. 5b). In contrary the
spectrum of nearest point (B) to tumor (see FIG. 6, part a, point 64)
shows only three distinct bands, where the structure labeled 53 (see FIG
5b) is reduced and nearly disappears in curve (B). Furthermore FIG. 8
indicates a typical FEW-FTIR spectra arising from pigment nevus
(noncancerous) for three different patients (A,B,C). It is evident that in
two cases (A and B) the four band positions 51 to 54 coincide, but in the
case C the peak positions 51 and 52 originating from amide I and amide II
are shifted. This is a clear indication of an early stage of cancer
revealed by an apparatus according to the present invention.
The invention is also concerned with means for comparing band structure,
peak positions, peak ratios etc., including visual displays of the spectra
to be compared. Alternatively, such means for comparing can be
superimposed. It is also possible to provide more sophisticated means for
comparing which calculate differences between different spectra, e.g.
subtracting one spectrum from another spectrum in order to reveal the
differences between the spectra.
Accordingly another object of this invention is to provide a method and
means for the diagnostics of premelanoma in vivo as shown in FIG. 9a and
b. When comparing normal (A) and premelanoma (B) tissues (see FIG. 9a), we
find that the four main band structures and the mean peak positions have
not changed, whereas the relative intensities of both amide bands
decreased. A practicable, reliable method available in this invention for
monitoring cancer and precancer is the determination of intensity ratios
for three band pairs: R.sub.I (I.sub.52 /I.sub.51), R.sub.II (I.sub.52
/I.sub.54), and R.sub.III (I.sub.54 /I.sub.53). In particular the
intensity ratio R.sub.II can be used for cancer and precancer diagnostics.
In FIG. 9b is shown a comparison of FEW-FTIR ex vivo measurement
(incision) for normal (A) and malignant (B) skin tissue (premelanoma) in
the same range as in FIG. 9a. From this figure it is apparent that the two
hydrogen bonded carbonyl bands 53 and 54 disappeared completely in spectra
of incision under the top layer of epidermis. In addition the intensity
ratio R.sub.I has changed substantially and the peak positions of the
bands 51 and 52 have shifted in opposite directions.
As another example of the foregoing diagnostic technique we display in FIG.
10a and b an extreme case of melanoma. As can be seen from FIG. 10a both
carbonyl bands 53 and 54 are absent for normal (A) and malignant (B) skin
surface points (see FIG. 6, part a). Furthermore the band maxima 51 and 52
exhibit characteristic shifts. Hence the distances in band position
between 51 and 52 can be used as another parameter for cancer diagnostics.
In addition there exists a pronounced difference in the intensity ratio
for R.sub.I in accordance of this invention. As can be seen in FIG. 10b,
dramatic changes occur in the FEW-FTIR spectra from normal (A) and
malignant (B) skin tissue (melanoma) below the epidermis (see FIG. 6, part
c) in the same range compared to FIG. 10a. It is further noted that the
peak 51 has partially collapsed. However a weak contribution of band 54
(carbonyl group) is observed exclusively for normal tissue.
With the apparatus of this invention FEW-FTIR spectra of malignant skin
tissues in vivo (basaloma) have been measured as indicated in FIG. 11. In
this figure are displayed spectra for normal (A) and malignant (B) skin
surfaces. Significant differences occur in peak positions, intensities,
intensity ratios and shape of band structures. Therefore basaloma can be
detected directly from the skin surface by comparing curve A and B (see
FIG. 11). Furthermore melanoma can be analyzed at the surface and below
the surface of the skin.
Another embodiment of this invention is an apparatus and method for
noninvasive, fast, direct, sensitive investigations in vivo of various
human skin points and zones including acupuncture (AC) points in the range
of about 800 to 4000 cm.sup.-1. Acupuncture is an ancient Chinese
diagnostic and treatment method (Ralph Alan Dale, Demythologizing
Acupuncture, Alternative Complementary Therapies (1997)) in which
electrodes or needles are used at specific points, connected with specific
organs. These acupuncture points are characterized by comparitively low
electrical resistance, and are well mapped. The subject of this invention
includes the surface response of different acupuncture points of the human
body using the FEW-FTIR method of this invention, for the purposes of
disease state characterization and development of new acupuncture
techniques. FIGS. 12a and b represent IR spectra showing an extremely
sensitive surface response of several AC points and differences between
various AC points, for example between lower lip 125 (RN24, middle of the
mentolobial groove) (Wu Shao, Body Model for Both Meridian and
Extraordinary Points of China, GB123 46-90), left ear 126, left elbow
crease 127 (LU5 elbow crease) in the spectral range of 800 to 1800
cm.sup.-1. In FIG. 12b are shown spectra associated with the same points
in the spectral interval 2500 to 4000 cm.sup.-1. In accordance with this
invention and the apparatus provided by the invention the peak positions,
intensities, widths, shapes, and intensity ratios of bands can be
compared. In particular the amide I and II region is sensitive to
Watson-Crick pairing. For example the appearance of the 1585 cm.sup.-1
structure, appearing in the spectra of the lower lip 125, left ear 126,
and left elbow crease 127 represents C.dbd.O stretching modes in guanine.
Another important fingerprint region of human skin AC points detected in
the range 2500 to 4000 cm.sup.-1 (see FIG. 12b) is concerned with C--H,
N--H, and O--H vibrations, as demonstrated for lower lip 128, left ear 129
and left arm 130. It can be seen that pronounced differences among the
different spectra are obvious in the system of amide A (proteins)
connected with N--H and O--H groups and lipid groups connected with C--H
vibrations.
FIGS. 13a and 13b show results for two AC points on the wrist, namely LU8
(8P) and LU9 (9P). In particular in FIG. 13a are indicated the IR spectra
results (800 to 1800 cm.sup.-1) for LU8,131 and LU9,132. Huge differences
are observed in the spectral range 800 to 1200 cm.sup.-1 attributed to
phosphate groups in lipid systems of human tissue. The higher wavenumber
range for the same AC points LU8 (8P) 133 and LU9 (9P) 134 is illustrated
in FIG. 13b, where the C--H vibrations due to aliphatic chains in lipids
show large differences. In the following detailed spectra (FIGS. 14a to
e), showing a spectral deconvolution of the main amide bands (1450-1800
cm.sup.-1 ) in the MIR range. In FIGS. l5a to e the same AC points are
represented in another spectral interval of C--H vibrations in the region
of 2800-3000 cm.sup.-1.
The bands 51,52,and 54 are assigned to vibrations of hydrogen bonded amide
II, amide I and carbonyl groups. In the three cases of lip, ear, and elbow
crease an additional band at 1590 cm.sup.-1 (55) is apparent (FIGS. 14a-c)
connected to Watson-Crick base pairing. In FIGS. 14d and e this band, as
well as the carbonyl bands (54), are absent. These differences are
connected with the content of lipids and/or proteins in tissue. The
present invention is embodied in the appearance and disappearance of the
band structures 53,54, and 55 as well as in the intensity ratio
I(52)/I(51) corresponding to the amide I and amide II bands. Another
object of the present invention is concerned with the bands 56,57,58,59,
and 60 in the wavenumber range 2800 to 3000 cm.sup.-1 (see FIGS. 15a to
e). In all cases displayed in FIGS. 15a to 15e peak 56 is assigned due to
C--H symmetric stretching in methylene groups (CH.sub.2) of lipids. The
band structure located at about 2922 cm.sup.-1 is identified as the
asymmetric stretching of methylene groups CH.sub.2 in lipids. Furthermore
peak 58 at approximately 2956 cm.sup.-1 arises from asymmetric stretching
vibration of methyl group (CH.sub.3). When comparing the spectra in FIGS.
15a,b,c,and e, the spectrum associated with the left wrist, acupuncture
point Lu9 (9P) differs in the weak intensity of the band 58 (see FIG.
15c). This change depends on the vibration of the methyl group. A special
situation arises for the spectrum from FIG. 15d (AC point 8P or LU8). Here
peak 58 is dominating the spectrum. In addition two new band features near
2874 cm.sup.-1 (59) and 2893 cm.sup.-1 (60) are observed originating from
symmetric stretching vibration of methyl group (CH.sub.3) and C--H
stretch.
It can be seen that the pronounced peak 58 occurring at 2972 cm.sup.-1 is
shifted substantially towards higher wavenumbers
(.DELTA..nu..about.16cm.sup.-1 ) when compared to the band structures 58
shown in FIGS. 15a,b,c and e. Therefore, peaks 58,59,and 60 can be used as
fingerprints for AC diagnostics.
In conclusion the infrared FEW-FTIR spectroscopic technology described in
this invention is not only very sensitive to cancer and precancer
diagnostics of human tissue, but also for the diagnostics of normal skin
and even for the characterization of specific acupuncture points. In
particular this invention relates to the surface response of human tissue
including AC points.
It is understood that the invention is not confined exclusively to the
particular embodiments on human skin described herein as illustrative, but
embraces the disease state characterization of other forms thereof within
the scope of the following claims.
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