AU4878199A - Method and apparatus for detecting electro-magnetic reflection from biological tissue - Google Patents

Description

S F Ref: 403070D1

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

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I Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: University of Arkansas University Tower Building, Suite 601 1123 South University Little Rock Arkansas 72204 UNITED STATES OF AMERICA Stephen T Flock, Louis Fink and Milton Waner Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Method and Apparatus for Detecting Electro-magnetic Reflection from Biological Tissue The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845 Description Background of the Invention The present invention relates to an imaging apparatus comprising a light source, an image detector and a monitor.

More particularly, the invention relates to a system -for locating anatomical structures such as blood vessels in a mammalian body by utilising equipment sensitive to the unique absorption and scattering characteristics of the target structure, such as blood.

Further, the present invention provides a system and method to enhance the contrast between a target structure, such as a blood vessel, and its surrounding tissue.

Every day in the United States, many hundreds-of-thousands of medical procedures involving the puncturing of blood vessels are performed. Venipuncture, as it is known, is required in order to administer emergency fluids, blood components, and anesthetics during operations, or to allow the drawing of blood for biochemical analysis.

15 Venipuncture, which is often the rate-limiting step when administering intravenous compounds, can take as long as a half hour with a typical patient or longer when the patient is a neonate, infant, geriatric, obese or burn patient. Notwithstanding the enormous financial burden on our society as a whole because operating rooms and healthcare providers must wait as an intravenous line is placed, the delay in placing an 20 intravenous line can in fact be life threatening. Furthermore, there is a high morbidity associated with multiple venipunctures caused by the clinician's failure to locate the ;vessel.

The reason venipuncture is sometimes difficult to do is that the blood vessels are often located relatively deep within the tissue which, because of its absorptive and 25 scattering optical properties, makes visualisation of the blood vessel impossible under normal conditions.

2 Furthermore, the situation is made worse by the fact that the vessel may spasm and constrict if it is manipulated too much. Consequently, health care providers have a need to visualize blood vessels in real-time during venipuncture in order to reduce the risk to the patient, save time and reduce the cost of the procedure. Furthermore, reducing the time of the procedure limits the providers' exposure to a potentially contaminated needle. Finally, visualization of vascular tissue can provide important diagnostic and therapeutic information about certain diseases such as thromboses, cancers or vascular malformations.

In the mid-1970's an instrument was devised that purportedly provided surgeons with the ability of visual- 15 izing superficial blood vessels. It consisted of a visible light source which, when pressed up against the skin, transilluminated the subcutaneous tissue and aided S:in the visualization of superficial blood vessels. The Sblood-vessel transilluminator made use of the different absorption properties of blood and tissue. Because blood strongly absorbs certain wavelengths of light, while fat Sand skin absorb other wavelengths, a health-care provider purportedly could visually distinguish the position of the subcutaneous blood vessel with the naked eye. The transilluminator has essentially fallen into disuse because it fails to provide enough contrast between the blood vessel and tissue to be of use other than for venipuncture of superficial vessels. Furthermore, some versions of the blood-vessel transilluminator caused thermal damage to the patient.

The transilluminator's failure revealed that high contrast was of critical importance to medical personnel.

Consequently, several references proposed using an illumination wavelength which penetrates surface tissue to a depth of the deep vessels but which is also highly absorbed by the blood. See, Cheong, W-F, et al., "A Review of the Optical Properties of Biological Tissues," 3 IEEE Journ. Quant. Elec., 26:2166-2185 (1990). These references, however, did not disclose efficient means of eliminating detection of scattered light from areas outside the vessel region off angle light). Nor did they disclose the elimination of detection of polychromatic white noise, such as from ambient room light or from a polychromatic light source. Later devices only employed a subtraction technique using expensive digital processing and cumbersome computer analysis to eliminate unwanted scattered waves.

Furthermore, these devices did not disclose a method of noise reduction for use with a white light source, but rather relied on use of a monochromatic laser light source to reduce polychromatic noise. Accordingly, there was a need for a contrast enhancement i• device useable with a polychromatic light source or in a polychromatic clinical environment.

Most importantly, electromagnetic imaging devices have used transmitted rather ooooo than reflected light to construct their image. Such systems house the image detector and o\ the light source on either side of the patient rather than side by side in a single integral is unit. Such an arrangement unfortunately does not allow for convenient same-side illuminating and detecting such as in the form of a single unit goggle or scanning device.

Accordingly, manipulation of many of these devices along with the patient required multiple clinical personnel. Moreover, these references in fact teach away from the use of any scattered light to create an image, including reflected light. Instead, these devices seek to eliminate all scattered light from detection since such light was thought not to carry any image information. Such an imaging apparatus is for instance known from US Patent No. 4,817,622.

Summary of the Invention *According to a first embodiment of this invention, there is provided an imaging apparatus comprising: a light source; an image detector; a monitor which displays an image of an internal anatomical structure received from said image detector; characterized in that the image detector is designed in order to detect light from said light source which is directly reflected and singularly scattered from a biological target tissue; 3a a contrast enhancing element is provided including means for substracting multiple scattered light reflected from a surrounding tissue other than a target anatomical structure from light directly reflected and singularly scattered from the target anatomical structure.

According to a second embodiment of this invention, there is provided an imaging apparatus comprising a light source wherein said light source comprises a monochromatic source within the infrared range and wherein said monochromatic light source within the infrared range comprises means for illumination within the range of 700-900nm; an image detector which detects light from said light source after it has been reflected from a biological target tissue; and a monitor which displays an image of an internal anatomical structure from said image detector.

According to a third embodiment of this invention, there is provided an imaging apparatus comprising a light source; o °an image detector further comprising a video camera which detects light from said light source after it has been reflected from a biological target tissue; and a monitor which displays an image of an internal anatomical structure received from said image detector.

According to a fourth embodiment of this invention, there is provided an imaging Sapparatus comprising a light source; 20 an image detector further comprising a liquid crystal telephone detector which detects light from said light source after it has been reflected from a biological target tissue; and a monitor which displays an image of an internal anatomical structure received from said image detector.

According to a fifth embodiment of this invention, there is provided an imaging S 25 apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element wherein said contrast enhancing element includes at least one bandpass filter; and a monitor which displays an image of an internal anatomical structure received from said image detector.

According to a sixth embodiment there is provided an imaging apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected from a biological target tissue; [R:\LI IZZ]06008.doc:NJC 3b a contrast enhancing element wherein said contrast enhancing element includes at least one bandpass filter which passes wavelengths around 800nm; and a monitor which displays an image of an internal anatomical structure received from said image detector.

According to a seventh embodiment there is provided an imaging apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected from a biological target tissue; wherein said contrast enhancing element includes a digital processor filter; and a monitor which displays an image of an internal anatomical structure received from said image detector.

According to an eighth embodiment there is provided an imaging apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected fiom a biological target issue; a contrast enhancing element wherein said contrast enhancing element includes at least one collimator; and a monitor which displays an image of an internal anatomical structure received from Ssaid image detector.

20 According to a ninth embodiment there is provided an imaging apparatus comprising; a light source; an image detector which detects light from said light source transmitted through biological target tissue a monitor which receives and displays image information from said image detector; and a contrast enhancing element which includes a first polarising optical element in the path of incident light between said light source and said biological tissue and a second polarising optical element in the path of the transmitted light between the non-light source side of the tissue and said image detector.

According to a tenth embodiment there is provided an imaging apparatus comprising: a light source; an image detector which detects light from said light source reflected from a biological target tissue; a monitor which receives and displays image information from said image detector; and fR:\LIBZZ]06008.doc:NJC 3c a contrast enhancing element which includes a polarising optical element in the path of incident light between said light source and said biological tissue and a polarising selecting optical element in the path of the reflected light between the said biological tissue and said image detector.

According to a eleventh embodiment there is provided an imaging apparatus comprising: a light source; an image detector which detects light from said light source transmitted through biological target tissue; a monitor which receives and displays image information from said image detector; and a contrast enhancing element including a modulation source and a light phase modulator connected to said modulation source.

According to a twelfth embodiment there is provided an imaging apparatus 15 comprising: S.a light source; an image detector which detects light from said light source reflected from a biological target tissue; a monitor which receives and displays image information from said image detector; and S- a contrast enhancing element including a modulation source and a light phase modulator connected to said modulation source.

According to a thirteenth embodiment there is provided an imaging apparatus comprising: S 25 a light source; an image detector which detects light from said light source reflected from a biological target tissue; a monitor which receives and displays image information from said image detector; and a contrast enhancing element including an illumination intensity modulation source.

According to a fourteenth embodiment there is provided an imaging apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected from a biological target tissue wherein said light s6urce and said image detector are part of a single integral unit; and [R:\LI BZZ]06008.doc:NJC a monitor which displays an image of an internal anatomical structure received from said image detector.

According to a fifteenth embodiment of this invention, there is provided an imaging apparatus comprising: a light source wherein said light source comprises a dual-wavelength illumination source; an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element; and a monitor which displays an image of an internal anatomical structure received from said image detector wherein said monitor comprises a means to rapidly alternate the display of the image reflected at each respective wavelength.

According to a sixteenth embodiment of this invention, there is provided an imaging S* apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element wherein said contrast enhancing element includes an exogenous dye adsorbed within the biological target tissue; and a digitising frame grabber connected to said image detector.

20 According to a seventeenth embodiment of this invention, there is provided an imaging apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element wherein said contrast enhancing element includes a 25 monoclonal antibody attached to the target biological tissue; a digitising frame grabber connected to said image detector; and a monitor which displays an image of an internal anatomical structure received from said image detector.

According to a eighteenth embodiment of this invention, there is provided an imaging apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element wherein said contrast enhancing element includes a molecule collected on plaque within a blood vessel; a digitising frame grabber connected to said image detector; and [R:\LIBZZ]06008.doc:NJC 3e a monitor which displays an image of an internal anatomical structure received from said image detector.

According to a nineteenth embodiment of this invention, there is provided an imaging apparatus comprising a light source; an image detector further comprising a liquid crystal television detector which detects light fromn said light source after it has been reflected from a biological target tissue and said light source and said detector are phase modulated in synchronicity; and a monitor which displays an image of an internal anatomical structure received from said image detector.

According to a twentieth embodiment of this invention, there is provided an imaging apparatus comprising a light source; an image detector further comprising a photorefractive crystal which detects light from said light source after it has been reflected from a biological target tissue; and ooooo a monitor which displays an image of an internal anatomical structure received from said image detector.

According to a twenty first embodiment of this invention, there is provided a method for imaging an anatomical structure comprising illuminating a biological tissue; wherein said step of illuminating comprises illuminating with a wavelength of between 700-900nm; detecting the reflected image from said biological target tissue; and o displaying said reflected image on a monitor.

According to a twenty second embodiment of this invention, there is provided a method for imaging an anatomical structure comprising illuminating a biological target tissue; bandpass filtering the light of interest; detecting the reflected image from said biological target tissue; and displaying said reflected image on a monitor.

According to a twenty third embodiment of this invention, there is provided an imaging apparatus comprising a light source wherein said light source comprises a monochromatic source within the infrared range and wherein said monochromatic light source within the infrared range comprises means for illumination within the range of 700- 900nm; an image detector which detects light from said light source after it has been reflected from a biological target tissue wherein said light source and said image detector are part of a unit; and [R:\LI BZZ]06008.doc:NJC a monitor which displays an image of an internal anatomical structure from said image detector.

According to a twenty fourth embodiment of this invention, there is provided an imaging apparatus comprising a light source wherein said light source comprises a monochromatic source within the infrared range and wherein said monochromatic light source within the infrared range comprises means for illumination within the range of 700- 900nm; an image detector which detects light from said light source after it has been reflected fi-om a biological target tissue; a monitor which displays an image of an internal anatomical structure from said image detector; and a helmet comprising said light source and image detector.

According to a twenty fifth embodiment of this invention, there is provided an oooeo "imaging apparatus comprising a light source wherein said light source comprises a monochromatic source within the infrared range and wherein said monochromatic light source within the infrared range comprises means for illumination within the range of 700- 900nim; an image detector which detects light from said light source after it has been reflected from a biological target tissue; and S 20 a monitor which displays an image of an internal anatomical structure from said image detector wherein said image detector and said monitor are part of a unit.

According to a twenty sixth embodiment of this invention, there is provided an imaging apparatus comprising a light source wherein said light source comprises a monochromatic source within the infrared range and wherein said monochromatic light S 25 source within the infrared range comprises means for illumination within the range of 700- 900nm; an image detector which detects light from said light source after it has been reflected from a biological target tissue; a monitor which displays an image of an internal anatomical structure from said image detector; and a head piece attached to said monitor.

According to a twenty seventh embodiment of this invention, there is provided an imaging apparatus comprising a light source wherein said light source comprises a source within the infrared range; [R:\LIBZZ]06008.doc:NJC 3g an image detector which detects light from said light source after it has been reflected from a biological target tissue; and a monitor which displays an image of an internal anatomical structure received from said image detector wherein said monitor and said image detector are part of a unit.

According to a twenty eighth embodiment of this invention, there is provided an imaging apparatus comprising a light source wherein said light source comprises a source within the infrared range; an image detector which detects light from said light source after it has been reflected from a biological target tissue wherein said image detector and said light source are part of a unit; and a monitor which displays an image of an internal anatomical structure received from said image detector.

According to a twenty ninth embodiment of this invention, there is provided an oooll imaging apparatus comprising a light source wherein said light source comprises a source within the infrared range; o o.,an image detector which detects light from said light source after it has been reflected from a biological target tissue; a helmet comprising said light source and said image detector; and a monitor which displays an image of an internal anatomical structure received S 20 from said image detector.

According to a thirtieth embodiment of this invention, there is provided an imaging apparatus comprising a light source wherein said light source comprises a source within the infrared range; i9 an image detector which detects light from said light source after it has been reflected from a biological target tissue; and a helmet comprising said image detector, said light source and a monitor which displays a image of an internal anatomical structure received from said image detector.

According to a thirty first embodiment of this invention, there is provided an image apparatus comprising a light source; an image detector further comprising a video camera which detects light from said light source after it has been reflected from a biological target tissue wherein said image detector and said light source are part of a unit; and a monitor which displays an image of an internal anatomical structure received from said image detector.

[R:\LIBZZ]06008.doc:NJC 3h According to a thirty second embodiment of this invention, there is provided an imaging apparatus comprising a light source; an image detector further comprising a video camera which detects light from said light source after it has been reflected from a biological target tissue; a monitor which displays an image of an internal anatomical structure from said image detector; and a helmet comprising said light source and image detector.

According to a thirty third embodiment of this invention, there is provided an imaging apparatus comprising a light source; an image detector further comprising a video camera which detects light from said light source after it has been reflected from a biological target tissue; and a monitor which displays an image of an internal anatomical structure from said image detector wherein said image detector and said monitor are part of a unit.

•oooo S. According to a thirty fourth embodiment of this invention, there is provided an imaging apparatus comprising a light source; *an image detector further comprising a video camera which detects light from said ,,light source after it has been reflected from a biological target tissue; a monitor which displays an image of an internal anatomical structure from said image S- detector; and A head piece attached to said monitor.

According to a thirty fifth embodiment of this invention, there is provided an imaging apparatus comprising: a light source; ia*a.. an image detector which detects light from said light source transmitted through biological target tissue; a monitor which receives and displays image information from said image detector; a head piece attached to said monitor; and a contrast enhancing element which includes a first polarising optical element in the path of incident light between said light source and said biological tissue and a second polarising optical element in the path of the transmitted light between the non-light source side of the tissue and said image detector.

According to a thirty sixth embodiment of this invention, there is provided an imaging apparatus comprising a light source in the infrared image: an image detector which detects light from said light source transmitted through biological target tissue; [R:\LIBZZ]06008.doc:NJC 3i a monitor which receives and displays image information from said image detector; a head piece attached to said monitor; and a contrast enhancing element which includes a first polarising optical element in the path of incident light between said light source and said biological tissue and a second polarising optical element in the path of the transmitted light between the non-light source side of the tissue and said image detector.

According to a thirty seventh embodiment of this invention, there is provided an imaging apparatus comprising: a light source; an image detector which detects light from said light source reflected from a biological target tissue; a monitor which receives and displays image information from said image detector; a head piece attached to said monitor; and a contrast enhancing element which includes a polarising optical element in the path is of incident light between said light source and said biological tissue and a polarising selecting optical element in the path of the reflected light between the said biological tissue and said image detector.

According to a thirty eighth embodiment of this invention, there is provided an imaging apparatus comprising a light source in the infrared image: an image detector which detects light from said light source reflected from a 1,biological target tissue; a monitor which receives and displays image information from said image detector; and a contrast enhancing element which include a polarising optical element in the path of incident light between said light source and said biological tissue and a polarising selecting optical element in the path of the reflected light between the said biological tissue and said image detector.

According to a thirty ninth embodiment of this invention, there is provided an imaging apparatus comprising: a light source wherein said light source comprises a dual-wavelength illumination source an said imaging apparatus further comprises an optical fibre bundle wherein said light source is coupled to said optical fibre bundle; an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element; and [R:\LIBZZ]06008.doc:NJC a monitor which displays an image of an internal anatomical structure received from said image detector.

In the present invention, a system and method is provided to view an anatomical structure such as a blood vessel in high contrast with its surrounding tissue. It is an object of the invention to product an image of an s 0*S* 0** Se

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[R:\LIBZZ06008.doc:NJC 4 anatomical structure using reflected electromagnetic radiation singularly scattered from the target tissue.

Yet another object of the present invention is to provide a method and apparatus for producing a clear three-dimensional image of an anatomical structure by detecting the electromagnetic radiation characteristics reflected from the target area.

Another object of the invention is to provide sameside illuminating and detecting of reflected electromagnetic radiation for use in a convenient integral imaging device.

Still another object of the present invention is to provide helmet mounted imaging technology in a single ~integral helmet which allows the wearer to view an anatomical structure located within a patient such that the image is continuously oriented according to the orientation o he helmet wearer's head.

Yet another object of the present invention is to provide a method and apparatus for quickly, accurately and efficiently allowing for the performance of venipuncture.

Another object of the present invention is to provide a method and apparatus for improving contrast between any anatomical structure and its surrounding tissue for use in any imaging system.

These and other objects of the present invention are achieved by one or more of the following embodiments.

Description of the Drawings Fig. 1 is a schematic diagram of the basic imaging system constructed in accordance with the principles of the present invention.

Fig. 2 is a schematic diagram of a further embodiment disclosing a light source emitting two distinct wavelength ranges and a digital image processor and frame grabber for enhancing image contrast.

Fig. 3 is a schematic diagram of a further embodiment disclosing a system using collimators to eliminate multiply scattered light.

Fig. 4 is a schematic diagram disclosing a system for performing phase-modulated detection of a reflected image.

Fig. 5 is a schematic diagram of an imaging helmet apparatus in accordance with the principles of the present invention.

Description of the Invention The present invention provides a system for locating an anatomical structure, such as a blood vessel, wherein the system comprises a light source and an image detector, which detects light radiation reflected from the area of examination, and a monitor which receives and displays 15 image information from said image detector. The term "light source" inc1urie hut Js not It- t p- I VL i to poiychromatic sources, such as white light sources, as well as monochromatic sources such as laser light sources. The term "image detector" refers to any device capable of 20 detecting light, including but not limited to charge- ~coupled device infrared cameras (CCD's), video cameras, and liquid crystal television detectors.

Optionally, the present invention may include elements that enhance the contrast between the anatomical structure 25 and the surrounding tissue in the image. The term "contrast enhancing element" refers to any element or combination of elements which enhance contrast between the anatomical structure and its surrounding tissue in the image, including elements which eliminate light outside the wavelengths of interest and elements which reduce multiply scattered light from the biological tissue in the tissue region of interest or eliminate multiply scattered light from the biological tissue adjacent to the region of interest. The contrast enhancing element as herein defined includes, but is not limited to, bandpass filters, digital processing filters, collimators, polarizing optical elements, photorefractive crystals, digital frame grabbers, blink imaging monitors, phase modulators, confocal-optical devices, exogenous dyes, and vascular modifying procedures.

The instant invention of detecting reflected light allows the light source and the reflected image detector to be part of a single integral unit. Such a single unit provides for convenient use, allowing a caregiver to hold the unit or wear the unit and as in the form of a helmet.

As explained in greater detail below, the possibility of a single integral unit also provides for the creation of :a helmet capable of producing a real-time three-dimensional image of an area inside a patient in a manner that directly corresponds to the helmet wearer's line of 15 vision. In one variation of this aspect of the invention, a single integral unit comprises a helmet, at least one light source and east one imaging detector mounted on the helmet. Additionally, the helmet may contain a monitor, such as a monitor within an eye piece, which displays the contrasted image of the anatomical structure being viewed by the helmet wearer. In a preferred embodiment, two imaging detectors mounted onto eyepieces of the helmet receive electromagnetic radiation information ~reflected from the patient. The light source may optionally be coupled to an optical filter bundle, the end of which is pressed against the skin so as to reduce specular reflection. The information is then used to create a three-dimensional image for real-time transmission to a monitor such as a monitor contained within an eyepiece of the headgear. Such embodiment allows the wearer to see the contrasted structure within a patient in a way which corresponds to the wearer's own line of vision.

In another embodiment of the invention, the image detector and light radiation source are part of a single integral scanning device which is passed over the area of interest. In this embodiment the single scanning device can be a handheld scanner or a movable mounted scanner, either one attached to a portable monitor. Such an embodiment allows for mobile scanning by a caregiver.

I

another embodiment the monitor itself can be part of the scanner.

According to a second feature of this invention, a variety of embodiments can be used to enhance contrast between the anatomical structure and its surrounding tissue. In one such embodiment the light source projects a broad range of wavelengths, including wavelengths absorbed by the anatomical structure, such as between approximately 700-900 nm for blood. The light is then passed through a bandpass filter which passes only the .desired wavelengths, e.g. 700-900 nm. The light is bubsequently absorbed by the target structure, e.g. the 15 blood vessel tissue, but not its surrounding tissue.

Alternatively, the filter may be placed in the path of the reflected li rfleted ligt be it reaches the detector, thus :eliminating polychromatic noise. The imaging detector 20then sends a signal to an image monitor. In a preferred embodiment the imaging detector is a CCD camera.

In another contrast enhancing embodiment, a laser which produces radiation at a single wavelength within the desired range, e.g. 700 -900nm, is used as the source of illumination. The target tissue including the target 25 anatomical structure, such as the blood vessel, is irradiated with light. Only unabsorbed light within the important range is then reflected back to the image detector.

Such embodiment allows for reduction of any other polychromatic light which serves as a source of background noise in the image. Specific wavelengths such as 730nm for bilirubin, l158nm and 1210nm for fat, and 760nm for hematomas may be used to detect other anatomical structures.

In another embodiment, a polarizing optical element such as a polarizing prism can be added to or can replace the bandpass filter. By polarizing the light before it reaches the tissue the reflected light will also be polarized in a particular plane with respect to the tissue. Thus, a Polarizing optical element Placed in front of the detector can Preferentially select out such radiation reflected by the tissue with the same polarization. Any highly scattered light (noise) and specular reflection will be filtered out since highly scattered light is randomly polarized and specular reflection is predominantly polarized in a different plane than the incident light. This polarizing element embodiment may be used with transilluminated light detection systems as well as reflected light detection systems.

In another embodiment, collimators are used to eliminate much of the reflected radiation that is highly scattered. In a variation of this embodiment, both the 15 source and detector are scanned in a raster-type pattern with the image built up over the period of the raster scan. This variation allows for strong collimation of the reflected light.

In another embodiment a confocal imaging system is focused at a particular depth of interest. Light from different depths and different positions is rejected by use of a collimator at the focal point of the optics. The S. image is then built up by raster-scanning the object to be imaged.

25 In still another embodiment the tissue is illuminated at two wavelengths, one which is strongly absorbed by the target structure but not the surrounding tissue and one, with approximately the same scattering efficiency, that is weakly absorbed by both the target structure and the surrounding tissue. The two images are sequentially captured with a digitizing frame grabber, stored and subtracted from one another. The resultant image lacks the effects of scatter present in each image since scattered light is subtracted out. In a variation, two wavelengths alternate illuminating the target and being displayed on the monitor. The viewer sees images fed to the monitor in alternating fashion. Because the human eye is especially sensitive to relatively rapid changes in light intensity, the viewer is sensitive to the highly contrasted anatomical structure image. This blink imaging process eliminates the need for expensive digital electronic processing to subtract the signals. In another embodiment, the source illumination is phase modulated by connecting a modulation source to a light phase modulator such as a Kerr cell. The modulation source also modulates the image detector such that the detector measures only 0 electromagnetic radiation that has the same state of modulation as the incident light. This embodiment has the iadvantage that highly scattered light, devoid of image "*'*."information, is phase-shifted Consequently, highly scattered light will not be detected. In another embodi- 1 mn the ouai s 15 ment the modulation is accomplished by varying illumina- tion intensity rather than the illumination phase such as by modulating the diode laser power supply. with the Model S1011 diode laser modulating power supply from Thor- Labs, Newton, Both of these modulation embodiments may be used with transilluminated light detection systems as well as reflected light detection systems.

In still another embodiment to enhance image contrast, an exogenous dye is administered to the patient which then collects within the anatomical structure of interest. The 25 exogenous dye is highly absorptive of a particular wave- length of light relative to the surrounding tissue. An image prior to dye application can be taken and then subtracted from an image taken after dye application.

Such a method subtracts out the unwanted noise common to both images and leaves only an enhanced image. Alternatively, the images can be alternately displayed so that the operator views the highly contrasted image by virtue of the aforementioned blink imaging process. In another embodiment the exogenous dye is collected by the surrounding tissue but not the anatomical structure of interest thereby creating image contrast.

In another embodiment the image detector is a liquidcrystal television detector such as available from Sony Electronics, Inc. Itasca, IL. The liquid crystal television detector can provide phase sensitive detection See Alliance for Photonic Technology Industrial Quarterly, Vol.3, no.2, p.3 (Winter/Spring 1995). In this embodiment the light source is phase modulated in synchronicity with the detector such that the detector captures only the light modulated at the same frequency and ignores all other light. Consequently, highly scattered light which has phase shifted with respect to the incident source light, is eliminated.

In yet another embodiment the image detector is a 15liquid crystal television detector which captures all phase information. However, instead of phase modulating the incident light, the detector captures light of all phases, and then sends phase information along with intensity information to a device which is used to construct a three-dimensional image of the anatomical structure. By capturing phase information this embodiment can do real-time holography in three dimensions. In a variation of this three-dimensional image embodiment a photorefractive crystal or polymer Lithium Niobate from CSK Optronics, Culver City, CA) is directly used as an image detector to capture the image. A hologram image is then created by illuminating the crystal or polymer in real-time. Alternatively, the crystal or polymer may receive its input from the output of the liquid crystal television detector.

Detailed Descrtions of the Preferred Embodiments An imaging system constructed in accordance with the principles of the present invention is shown in Fig. i, and includes a light source 2 radiating a beam of incident light 4 upon a biological tissue 6, such that the beam is partially transmitted through the biological tissue until being absorbed by the target anatomical structure 8. An 11 image detector 12, Model CCD-72 camera available from Dage-MTI, Inc.) detects reflected light 16, predominantly reflected from tissue surrounding the target anatomical structure with a different absorptive wavelength than the anatomical structure. The image detector 16 is connected by a video signal 18 to a monitor 14 so that the intensity information of incident light reflected from the tissue is displayed onto the monitor in the form of an image. If a polychromatic light source is used, wavelengths outside the useful range for imaging the target structure should be filtered out by one or more bandpass filters 10. Alternatively, the imaging detector can detect only wavelengths within the useful range, such I as occurs with a charge-coupled device infrared camera (CCD) CCD1350-1 infrared CCD camera and 9300-00 *image intensifier available from Electrophysics Corp Fairfield NJ). Alternatively, a real-time digital image processor such as described in Fig. 2, CSP-2000 Processor available from Dage-MTI Inc.) can be used to filter out information poor wavelengths generated by the :polychromatic light source.

In an alternative embodiment of the invention, a polarizing optical element 22a such as a polarizing filter available from Ealing Electro-Optics Ind.

25 .Holliston, MA or Oriel Corp., Stratford, CT) is used in combination with a laser or other monochromatic light source. Monochromatic sources include, by way of example, the Model 6124 laser diode available from New Focus, Inc.

Sunnyvale CA, the Model Micralase available from Micracor, Inc., Acton MA, and the MDL-DLAW10 available from McDonnell Douglas Aerospace, St. Louis MO. The polarizing filter, by polarizing the incident light in a particular plane with respect to the tissue will cause the singularly reflected light to be of a distinct polarization.

A

second polarizing optical element 22b in front of the detector then preferentially selects out singularly reflected radiation from the light source. Multiply scattered radiation, which carries little image information, is typically randomly Polarized and thus will not pass through the second polarizing optical element 22b and onto the image detector 12. The polarizing filters can be used with either the bandpass filter 0, the chargecoupled device infrared camera, the digital image processor of Fig. 2 or any combination of these three in the event a polychromatic light source is used for the light source 2. Any combination of these elements may also be used when the light source 2 comprises a laser or other monochromatic light source.

A further embodiment of the invention is shown in Fig 2. for an imaging system with a digital image processor and frame grabber 24 (such as the CSP-200 0 processor 15 available from Dage-MTI Inc.). In this embodiment the tissue can be illuminated by a light source 20 projecting at least two wavelengths. In a preferred embodiment the biological tissue 6 is illuminated by a wavelength that Penetrates the tissue yet is weakly absorbed by the target anatomical structure 8. In the case of a blood vessel containing blood, the wavelength of between 7 00nm and 90 0nm, preferably around 8 00nm, would suffice. The reflected image is then captured with a digital image processor, containing a digital frame grabber, and stored.

Next, the same tissue field is illuminated by a second wavelength which is close enough in frequency to the first wavelength such that the tissue scattering efficiency is about the same. However the second wavelength must either be more weakly or more strongly absorbed by the target anatomical structure. This second image is captured and subtracted from the previous by the digital image processor 24; thus the effects of scatter are removed from the resulting image and only the absorption difference between the two images shows.

Another embodiment of the two-wavelength approach eliminates the digital image processor 24 altogether. By illuminating the biological tissue with two wavelengths and alternating the display of the image reflected by each separate wavelength on the monitor 14 the target anatomical structure will sequentially appear and disappear. The human eye is especially sensitive to relatively rapid changes in light intensity, and through a physiological process known as blink imaging would detect the outline of the target structure.

A further embodiment of the invention is shown in Fig. 3, disclosing a system using collimators to eliminate multiply scattered light. Components corresponding to those already identified in connection with Fig. 1 have Sthe same reference numerals. In this embodiment at least one collimator 26 is used to stop multiply scattered photons 28 from reaching the image detector 12. In this 915 way, strong collimation reduces the background noise not useful for producing an image. Extremely strong collimation, if required, might necessitate the light source and image detector to be scanned in a raster-type pattern and the image built up over the period of a raster scan. The collimators may be used in combination with any of the possible combinations of contrast enhancing elements shown in Fig. 1 and Fig. 2. When the light source 2 is polychromatic, the collimators should be used in combination with a bandpass filter 10, a selective image detector 12 :25 such as a infrared CCD, a digital image processor 24, or any other device capable of eliminating reflected light outside the wavelength of interest.

Another embodiment of the invention is shown in Fig.

4 disclosing a system for performing phase-modulated detection of a reflected image. In this embodiment, incident laser light is phase modulated by a modulation source 30 which controls a light phase modulator 28 such as a rotating aspheric optic or a Kerr cell available from Meadowlark Optics, Longmont CO., Advanced Optronics Inc., San Jose CA., or Ninds Instruments Inc., Nillsboro OR.) The modulation source 30 controls the phase-sensitive imaging detector 32 such as a liquid crystal video television. Thus, the image detector only measures the reflected light that has the same state of modulation as the incident light. All other light is removed from the measurement. Because highly scattered light is phase-shifted, that light too would also be eliminated. The modulation source 30 may also comprise two independent phase-matched sources, one controlling the modulator 28 and one controlling the detector 32.

A further embodiment of the invention is shown in Fig.

5 which discloses a system of conducting binocular stereo imaging of a target anatomical structure. In this preferred embodiment, three dimensional depth information is incorporated within the image by detecting two angles of reflected light from the target tissue area using two 15 imaging detectors 34a and 34b Model 8900 infrared sensitive video cameras with focussing eyepieces and objective lenses from FJW Optical Systems Inc., Palatine, IL.) In one variation of this embodiment a light source 38 MDL-DLAW10 diode laser from McDonnell Douglas Aerospace, St. Louis, MO, with LD1001 driver from Thor- Labs, Newton NJ and 12 V DC source) is mounted on a helmet 40 The Physician's Headlight from Welch-Allyn Inc., Skaeneateles Falls, NY) which in turn holds the two imaging detectors 34a and 34b. The light source output 25 may optionally be focussed with diode laser collimation optics Model LT11OP-B from Thor-Labs, Newton,

N.J.)

to produce about a 1mm spot at a distance of about inches. The incident light 4 is reflected back from the target tissue as 16a and 16b.

In a variation of the preferred embodiment bandpass filters 46a and 46b 808nm center wavelength filters Model BP Series-3 Cavity from Omega Optical, Inc., Brattleboro, VT) are positioned in front of the video cameras to filter out all ambient light. In another variation, linear polarizing filters Model 27805 filters, from Oriel Corp., Stratford, CT) are placed, one between the laser light source and the tissue and the others on each eyepiece, thereby eliminating scattered (randomly polarized) light- The detectors each capture light reflected back at a slightly different angle creating a stereoscopic effect. The image detector's output 40a and 40b send the information to a monitor 14 for processing and eventual three-dimensional display of the highly contrasted tissue area. In a variation of this embodiment, the monitors may actually be in the eyepieces, 44a and 44b of the helmet, such as attached to or part of the image detectors 34a and 34b, thus allowing the goggle wearer to examine the subject as if seeing through the tissue surrounding the target anatomical structure.

In another variation of this embodiment, the two image detectors are mounted on an automated piece of surgical 15 equipment. The output of the detectors 34a and 34b are sent to a remote monitor which displays a three-dimensional image of the target tissue. The surgical equipment is then operated remotely using position-sensitive servo- S. motors. Accordingly, certain procedures such as venipuncture can be done remotely by the operator.

In another embodiment, image contrast is enhanced by the injection of an exogenous dye which is collected in the anatomical structure of interest. Alternatively, the exogenous dye is collected in the surrounding tissue but 25 not the anatomical structure of interest. For example, indocyanine-green (ICG) dye absorbs strongly near 800nm, where tissue is relatively transmitting. Flock, S. et al., "Thermal Damage of Blood Vessels using Insocyanine Green and a Pulsed Alexandrite Laser," Lasers Med. Sci., 8:185-196 (1993) A reflected image is taken using an 800nm illumination source. Then ICG is injected upstream, and a second image is taken. The first image is stored by the digital processor and the second image subtracted out by a digital processor and the result displayed as previously described. Alternatively, the operator can monitor the image using the blink imaging process as previously described without the aid of digitalrocessing. ther exogenous dyes such as hematoporphyrin can also be used.

In a variation of this embodiment, a monoclonal antibody to a particular antigen is linked to light absorbing chromophore. The antbody is then bound to the target tissue of interest. The target area is then illuminated with light of a wavelength absorbed by the chromophore and the resultant image detected Alternatively, a wavelength which excites a fluorophore bound to antibody may be fluorophore bound to antibody may be used whereupon fluorescence of the fluorophore s detected.wheTeo fe t h e fluorophore is detected. This technique can create an *image of any subcutaneous pathology bindable through antibody technology. For example, a monoclonal antibody to a hepatocyte cler surface antigen is injected and an image of the liver can be created by the present inven- .tion. Such a technique may be used in conjunction with any of the aforementioned systems and combinations S: ihn another variation of this embodiment, molecules S th e blood strea cholesteol affinity may be injected into the blood stream. These molecules then collect on plaque in the blood vessels. Hayashi et al., "Transadvential Localization of Atheromatous Plaques by Fluorescence Emission Spectrum Analysis of Mono-L-aspartyl-chlorin e6, Cardiovasc. Research, 27:1943- 1947 (1993). In this S 25 variation, an illumination wavelength is selected based upon the differential absorbance of the drug or, alternatively, the drug's capacity for florescence at a particular wavelength. The contrast image is then detected by the image detector after illumination at the appropriate wavelength.

In still another variation of this embodiment, images are taken of a blood vessel before a vascular modifying procedure is performed For example, a tourniquet can be applied to the vessel after a first image detection, thus modifying blood density A second image then is detected and subtracted from the first image. Alternatively, ice can be applied to the cutaneous surface after a first 17 detection, thus modifying blood flow. Again, the postmodifying procedure image is subtracted from the premodifying procedure image to create the outline of the vessel.

Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventors to embody with" e i n t e n t i o of the inventors to embody fithin the patent warranted hereon all changes and modifications as reasonable and properly come within the scope of their contribution to the art.

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Claims (22)

1. An imaging apparatus comprising: a light source; an image detector; a monitor which displays an image of an internal anatomical structure received from said image detector; characterized in that the image detector is designed in order to detect light from said light source which is directly reflected and singularly scattered from a biological target tissue; a contrast enhancing element is provided including means for substracting multiple 10 scattered light reflected from a surrounding tissue other than a target anatomical structure from light directly reflected and singularly scattered from the target anatomical structure.

2. The imaging apparatus of claim 1 wherein said light source is polychromatic source.

3. The imaging apparatus of claim 1 wherein said light source is a monochromatic source within the infrared range.

4. The imaging apparatus of claim 3 wherein said monochromatic light source illuminates within the range of 7 00-900nm. The imaging apparatus of claim 1 wherein said image detector is a charge coupled device infrared camera.

6. The imaging apparatus of claim 1 wherein said image detector is a video camera.

7. The imaging apparatus of claim 1 wherein said image detector is a liquid crystal television detector.

8. The imaging apparatus of claiml wherein said contrast enhancing element includes means for eliminating light outside the wavelength of interest.

9. The imaging apparatus of claim 8 wherein said contrast enhancing element includes at least one bandpass filter. The imaging apparatus of claim 9 wherein said bandpass filter passes wavelengths around 800nm.

11. The imaging apparatus of claim 8 wherein said contrast enhancing element includes a digital processor filter.

12. The imaging apparatus of claim 8 wherein said contrast enhancing element includes at least one collimator.

13. The imaging apparatus of claim 1 wherein said contrast enhancing element includes a first polarizing optical element in the patch of incident light between said light source and said biological tissue and a second polarizing optical element in the path of the reflected light between the said biological tissue and said image detector.

14. The imaging apparatus of claim 1 wherein said contrast enhancing element includes a modulation source and a light phase modulator connected to said modulation source. The imaging apparatus of claim 1 wherein said contrast enhancing element includes an illumination intensity modulation source.

16. The imaging apparatus of claim 1 wherein said light source and said image i detector are part of a single integral unit. S"17. The imaging apparatus of claim 16 wherein said single integral unit comprises a helmet.

18. The imaging apparatus of claim 17 wherein said monitor is part of said helmet. ~19. The imaging apparatus of claim 15 wherein said light source is coupled to an optical fibre bundle. The imaging apparatus of claim 15 wherein said image detector is an infrared sensitive video camera and said light source is a diode laser.

21. The imaging apparatus of claim 15 wherein said single integral unit is an automated piece of surgical equipment.

22. The imaging apparatus of claim 1 wherein said light source illuminates with at least two wavelengths and said image detector is connected to a digitizing frame grabber.

23. The imaging apparatus of claim 1 wherein said light source illuminates with at least two wavelengths and said monitor rapidly alternates display of the mage reflected at each respective wavelength. m age ref l ect at

24. The imaging apparatus of claim 1 wherein said contrast enhancing element includes an exogenous dye absorbed within the biological tissue; and a digitising frame grabber connected to said image detector. The imaging apparatus of claim 1 wherein said contrast enhancing element includes a monoclonal antibody attached to the target biological tissue; and a digitising frame grabber connected to said image detector.

26. The imaging apparatus of claim I wherein said contrast enhancing element includes a molecule collected on plaque within a blood vessel; and a digitising frame grabber connected to said image detector.

27. The imaging apparatus of claim 1 wherein said image detector is a liquid crystal television detector and said light source and said detector are phase modulated in 8. 15 synchronicity. n d d m latd *:28o An imaging apparatus as in claim 1 wherein said image detector is a photorefractive crystal.

29. An imaging apparatus, substantially as hereinbefore described with reference S to the accompanying drawings. 21 I. An imaging apparatus comprising a light source wherein said light source comprises a monochromatic source within the infrared range and wherein said monochromatic light source within the infrared range comprises means for illumination within the range of 700-900nm; an image detector which detects light from said light source after it has been reflected from a biological target tissue; and a monitor which displays an image of an internal anatomical structure from said image detector. 2. An imaging apparatus comprising a light source; I0 an image detector further comprising a video camera which detects light from said light source after it has been reflected from a biological target tissue; and a monitor which displays an image of an internal anatomical structure received from said imnage detector. 3. An imaging apparatus comprising a light source; an image detector further comprising a liquid crystal telephone detector which detects light from said light source after it has been reflected from a biological target tissue; and S-a monitor which displays an image of an internal anatomical structure received from said image detector. 4. An imaging apparatus comprising a light source; 2o an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element wherein said contrast enhancing element includes at least one bandpass filter; and a monitor which displays an image of an internal anatomical structure received from said image detector. An imaging apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element wherein said contrast enhancing element includes at least one bandpass filter which passes wavelengths around 800nm; and a monitor which displays an image of an internal anatomical structure received from said image detector. lR:\LIBZZ]06199.doc:NJC 22 6. An imaging apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected from a biological target tissue; wherein said contrast enhancing element includes a digital processor filter; and a monitor which displays an image of an internal anatomical structure received from said image detector. 7. An imaging apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected from a biological target issue; 0 a contrast enhancing element wherein said contrast enhancing element includes at least one collimator; and *.oa monitor which displays an image of an internal anatomical structure received fromn said image detector. 8. An imaging apparatus comprising; a light source; an image detector which detects light from said light source transmitted through biological target tissue a monitor which receives and displays image information from said image detector; and a contrast enhancing element which includes a first polarising optical element in the path of incident light between said light source and said biological tissue and a second polarising optical element in the path of the transmitted light between the non-light source side of the tissue and said image detector. 9. An imaging apparatus comprising: a light source; an image detector which detects light from said light source reflected from a biological target tissue; a monitor which receives and displays image information from said image detector; and a contrast enhancing element which includes a polarising optical element in the path of incident light between said light source and said biological tissue and a R:\LIBZZ]06199.doc:NJC 2-3 polarizing selecting optical element in th path of the reflected light between the said biological tissue and said image detector. An imaging apparatus comprising: a light source; toan image detector which detects light from said light source transmitted through biological target tissue; detector and a monitor which receives and displays image information from said image a contrast enhancing element including a modulation source and a light O phase modulator connected to said modulation source. :11. An imaging apparatus comprising: a light source; Sa biolo an image detector which detects light from said light source reflected from a biological target tissue; detector; and mo nitor which receives and displays image information from said image a contrast enhancing element including a modulation source and a light phase modulator connected to said modulation source, 12. an imaging apparatus comprising: a light source; Sian image detector which detects light from said light source reflected from a biological target tissue; detector; and a monitor which receives and displays image information from said image 2 odulati a contrast enhancing element including an illumination intensity modulation source. 13. An imaging apparatus comprising a light source; n image detector which detects light from said light source after it has been reflected from a biological target tissue wherein said light source and said image -0 detector are part of a single integral unit; and a monitor which displays an image of an internal anatomical structure received from said image detector. 14. An imaging apparatus as in claim 13 wherein said single integral unit comprises a helmet. is1. An imaging apparatus as in claim 14 wherein said monitor comprises part of said helmet. 16. An imaging apparatus as in claim 15 further comprising an optical fiber bundle wherein said light sourc is coupled to said optical fiber bundle. 17. An imaging apparatus as in claim 15 wherein said image detector io comprises an infrared sensitive video camera and said light source* comprises a diode laser. 18. An imaging apparatus as in claim 15 wherein said single integral unit comprises an automated piece of surgical equipment. 19. An imaging apparatus comprising: light sourcc wherein said light source comprises a dual-wavelength illumination source and said imaging apparatus fuirther comprises an optical fiber bundle wherein said light source is coupled to said optical fiber bundle; an image detector which detects light from said light source after it has been reflected from a biological target tissue; :a contrast enhancing element; and a monitor which displays an image of an internal anatomical structure received from said image detector. An imaging apparatus comprising: a light source wherein said light source comprises a dual-wavelength 2c illumination source; an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element; and a monitor which displays an image of an internal anatomical structure received .S C3 from said image detector wherein said monitor comprises a means to rapidly alternate the display of the image reflected at each respective wavelength. 21. An imaging apparatus comprising a light source. 2-G an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element wherein said contrast enhancing element includes an exogenous.dye adsorbed within the biological target tissue; and a digitizing frame grabber connected to said image detector. 22. An imaging apparatus comprising a light source; an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element wherein said contrast enhancing element includes a lo monoclonal antibody attached to the target biological tissue; a digitizing frame grabber connected to said image detector, and a monitor which displays an image of an internal anatomical structure received from said image detector. S. 23. An imaging apparatus comprising a light source; i an image detector which detects light from said light source after it has been reflected from a biological target tissue; a contrast enhancing element wherein said contrast enhancing element includes a molecule collected on plaque within a blood vessel; "a digitizing frame grabber connected to said image detector; and a monitor which displays an image of an internal anatomical structure received from said image detector. 24. An imaging apparatus comprising a light source; an image detector further comprising a liquid crystal television detector which detects light from said light source after it has been reflected from a biological target tissue and 2- said light source and said detector are phase modulated in synchronicity; and a monitor which displays an image of an internal anatomical structure received from said image detector. An imaging apparatus comprising a light source; an image detector further comprising a photorefractive crystal which detects light So from said light source after it has been reflected from a biological target tissue; and I a monitor which displays an image of an internal anatomical structure received from said image detetor. olo26. A method for imaging an anatomical structure comprising illuminating a biological tissue;

700-900wherein said step of illuminating comprises illuminating with a wavelength of between 700-900 nm; ing wth a veegth oftween detecting the reflected image from said biological target tissue; and displaying said reflected image on a monitor. 27. A method for imaging an anatomical structure as in claim 25 wherein said step of io detecting further comprises detecting with a charge coupled device infrared camera. .28 Amethodfor i: 28. A method for imaging an anatomical structure comprising illuminating a Sbiological target tissue; Sbandpass filtering the light of interest; detecting the reflected image from said biological target tissue; and *6 displaying said reflected image on a monitor. 29. An imaging apparatus comprising a light source wherein said light source comprises a monochromatic source within the infrared range and wherein said monochromatic light source within the infrared range comprises means for illumination within the range of 700- 900nm; o an image detector which detects light from said light source after it has been reflected from a biological target tissue wherein said light source and said image detector are part of a unit; and adetecto monitor which displays an image of an internal anatomical structure from said image "detector. 30. An imaging apparatus comprising a light source wherein said light source comprises a monochromatic source within the infrared range and wherein said monochromatic light source within the iared range comprises means for illumination within the range of 700- 900am; an image detector which detects light from said light source after it has been reflected et, from a biological target tissue; a monitor which displays an image of an internal anatomical structure from said image detector; and a helmet comprising said light source and image detector. 31. An imaging apparatus comprising a light source wherein said light source comprises a monochromatic source within the infrared range and wherein said monochromatic ght source within the infrared range comprises means for illumination within the range of 700- 900nm; San image detector which detects light from said light source after it has been reflected from a biological target tissue; and a monitor which displays an image f an internal anatomical structure from said image 32. An imaging apparatus comprising a light source wherein said light source o comprises a monochromatic source within the infrared range and wherein said monochromatic an image detector which detects light from said light source after it has been reflected rom a biological target tissue; I a monitor which displays an image of an internal anatomical structure from said image detector, and a head piece attached to said monitor. 33. The apparatus of claim 29 wherein said imaging apparatus further comprises a filter for eliminating light outside the wavelength of interest. 0 34. The apparatus of claim 32 wherein said imaging apparatus further comprises a filter for eliminating light outside the wavelength of interest The apparatus of claim 33 wherein said filter comprises a bandpass filter. 36. The apparatus of claim 29 wherein said imaging apparatus further comprises a contrast enhancing element and wherein said monitor is part of the same unit as said image 37. The apparatus of claim 30 wherein said helmet further comprises said monitor. 38. The apparatus of claim 37 wherein said imaging apparatus further comprises a filter for eliminating light outside the wavelength ofinteresL 39. The apparatus of claim 29 wherein a helmet is part of the same unit as the image detector and said light source. The apparatus of claim 39 wherein said imaging apparatus fiurther comprises a filter for eliminating light outside the wavelength of interest 41. The apparatus of claim 38 wherein said filter comprises a bandpass filter. 42. The apparatus of claim 40 wherein said filter comprises a bandpass filter. 43. The apparatus of claim 41 further comprising a contrast enhancing element which includes a polarizing optical clement in the path of incident light between said light source and said biological tissue and a polarizing selecting optical clement in the path of the reflected light i between the said biological tissue and said image detector. 44. The apparatus of claim 42 further comprising a contrast enhancing element which includes a polarizing optical element in the path of incident light between said light source and said biological tissue and a polarizing selecting optical element in the path of the reflected light between the said biological tissue and said image detector. O 45. The apparatus of claim 31 wherein said imaging apparatus further comprises a filter for eliminating light outside the wavelength of interest. i 46. ihe apparatus of claim 37 wherein said helmet is made of three head straps. "47. An imaging apparatus comprising a light source wherein said light source :""*comprises a source within the infrared range; 6 an image detector which detects light form said light source after it has been reflected from a biological target tissue; and a monitor which displays an image of an internal anatomical structure received from said -image detector wherein said monitor and said image detector are part of a unit 48. An imaging apparatus comprising a light source wherein said light source .o comprises a source within the infrared range; an image detector which detects light from said light source after it has been reflected from a biological target tissue wherein said image detector and said light source are part of a unit; and 2o.i a monitor which displays an image of an internal anatomical structure received from said 2" image detector. 49. An imaging apparatus comprising a light source wherein said light source comprises a source within the infrared range; an image detector which detects light from said light source after it has been reflected from a biological target tissue; So a helmet comprising said light source and said image detector; and a monitor which displays an image of an internal anatomical structure received from said iage detector. An inl~ing apparatus comprising a light source whereinsaid ligt sorc comprises a source within the infrared range; an image detector which detects light from sad light Source after it has been reflectedl from a biological target tissue; and a helmet comprising said imae detector, sai ih oreadamntrwihdsly an image of an internal anatomical structure recid fromt soeaid ma dmtectorwihdsly 51- The apparatus Of claim 47 wherein the apparatus fuirther comprises a contrast enhancing element. 52. lie apparatus of claimi 48 wherein the apparatus further comprises a contrast i o, enhancing element. 53- T7he apparatus of claim 49 wherein the apparatus further Comprises a contrast enhancing element.. 54. The= apparatus of claimi 50 wherein the apparatus further comprises a contrast *.enhancing element. 111e apparatus Of claim 51 wherein said contrat enhancinig element comprises a filter for eliminating ligh outside the wavelength of interest 56. -Ile apparatus Of claim 52 wherein said cntrast: enhancing element comprises a filter for elinminaing light outside the wavelenth of nerst 57. Ile apparatus Of claim 53 wherein said contrast enAnring element comprises a filter for eliminating light outside the wavelength of interest. The apparatus Of claim 54 wherein said contrast enhancing element comprises a filter for eliminating light outside the wavelength of interest. 5-9- The apparaUS Of claim 51 wherein said image detector comprises a charge coupled device infrared camera The apparatus Of claim 52 wherein said image detector comprises a charge coupled device infrared camera 61. The apparatuzs Of claim 53 wherein said image detector comprise a charge coupled device infrared camera 62. The apparatus of claim 54 wherein said image detector Comprises a charge c> coupled device infrared camera. 63. The- apparatus of claim 51 Wherein. said Con1trast enhancing element includes a Pololizing optical clemetnt in tile Path of incident liht between szaid light sourca and said biological tissue and a polarizing seleting optical clement in the path of the reflected light between the said biological tissue and said image detector. 64. The apparatus of claim 52 wherein said contrast enhancing elernent includes a polarizing optical element in the path of incident light between said light source and said S biological tissue and a polarizing selecting optical element in the path of the reflected light between the said biological tissue and said image detector. The apparatus of claim 53 wherein said contrast enhancing element includes a polarizing optical element in the path of incident light between said light source and said hiological tissue and asaid light source and said biological tissue and a polariing selectin optical element in the path of the reflected light 66. The apparatus of claim 54 wherein said contrast enhancing element includes a polarizing optical element in the path of incident light between said light source aid said biological tissue and a polarizing selecting optical element in the path of the reflected light between the said biological tissue and said image detector. 67. An imaging apparatus comprising a light source; an image detector further comprising a video camera which detects light from said light source after it has been reflected from a biological target tissue wherein said image detector and said light source are part ofa unit; and Sdete a monitor which displays an image of an internal anatomical structure received f said or s image detector. 68. An imaging apparatus comprising a light source; an image detector further comprising a video camera which detects light from said light source after it has been reflected from a biological target tissue; d a monitor which displays an image of an internal anatomical structure from said image A2G detector; and a helmet comprising said light source and image detector. 69. An imaging apparatus comprising a light source; an image detector further comprising a video camera which detects light from said light source after it has been reflected from a biological target tissue; and a monitor which displays an image of an internal anatomical structure from said image detector wherein said image detector and said monitor are part of a unit. An imaging apparatus comprising a light source; 3\ an image detector further comprising a video camera which detects light from said light source after it has been reflected fiom a biological target tissue; a monitor which displays an image of an internal anatomical stmucture from said image detector; and 6 a head piece attached to said monitor. 71. The apparatus of claim 67 wherein said imaging apparatus further comprises a filter for eliminating light outside the wavelength of interest. 72. The apparatus of claim 70 wherein said imaging apparatus further comprises a filter for eliminating light outside the wavelength of interest. S0 73. The apparatus of claim 71 wherein said filter comprises a bandpass filter. 74. The apparatus of claim 67 wherein said imaging apparatus frther comprises a contrast enhancing element and wherein said monitor is part of the same unit as said image detector and said light source. is f he sam as aid image The apparatus of claim 78 wherein said helmet further comprises said monitor. 76. The appartus of claim 75 wherein said imaging apparatus further comprises a filter for eliminating light outside the wavelength of interest. 77. The apparatus of claim 67 wherein a helmet is part of the same unit as the image e "detector and said light source. 78. The apparatus of claim 77 wherein said imaging apparatus further comprises a filter for eliminating light outside the wavelength of interest. 79. Te apparatus of claim 76 wherein said filter comprises a bandpass filter. The apparatus of claim 78 wherein said filter comprises a bandpass filter. 81. The apparatus of claim 67 furtler comprising a contrast enhancing element which includes a polarizing ptical element in the path of incident light between said light source and t w said biological tissue and a polarizing electing optical element in thepath ofthe reflected light between the said biological tissue and said image detector. 82. The apparatus of claim 68 further comprising a contrast enhancing clement which includes a polarizing optical element in the path of incident light between said light source and said biological tissue and a polarizing selecting optical element in the path of the reflected light between the said biological tissue and said image detector. 83. The apparatus of claim 69 wherein said imaging apparatus further comprises a filter forcliminating light outside the wavelength of interest. 84. The apparatus of claim 75 wherein said helmet is made of three head straps. An Wirn g apparatus comprising: a light source; an image detector which detects light from said light source transnittecl through biological target tissue;ns sa monitor which recei ves and displays image information from said image detector; a head picce attached to said monitor; and a1 contrast enhancing element which includes a first polarizing optical clement in the path of incident light between said light source and said biological tissue and a second plrzn optical element in the path of the transmitted] light between the non1-liht soresd pofh trisue 0O and said image detector. g rcsd fte.tsu 86. An imaging apparatus comprising a light source in the infrared mage an image detector which detects light from said light source transmitted through *biological target tissue; u a monitor which receives and displays image information from saidimgdectr a head piece attached to said monitor and contrast enhancing element which includes a first polarizing optica element inthe pat of incident light btensaid light source and said biological tissue and a second polarizing optical element in the Path of the transmitted light between the non-light source side of the tissue and said image detector. 87. An imaging apparatus comprising: a light source; an image detector which detects light from said light source reflected from a biological target tissue; a monitor w(hich receives and displays image information from said image detector; 5 a head piece attached to said mionitor, and a contrat enhancing element which includes a polarizing optical element in the path of incident light between said light source and said biological tissue and a polarizing selecting optical element in the path of the reflected light between the said biological tissue and said image detector. 88. An imging apparatus comprising a light source in the infrared image: 33 an image detector which detects light from said light source reflected from a biological target tissue; a monitor which receives and displays image information from said image detector; and a contrast enhancing element which includes a polarising optical element in the path of incident light between said light source and said biological tissue and a polarising selecting optical element in the path of the reflected light between the said biological tissue and said image detector. 89. A method of using the apparatus of claims 1, 29, 30, 31 or 32 wherein said to monitor is worn by the apparatus operator. 90. A method of using the apparatus of claim 1 or 29 wherein said unit is worn by the apparatus operator. 91. A method of using the apparatus of claim 1 or 29 wherein both said unit and said monitor are worn by the apparatus operator. 15 92. An imaging apparatus substantially as herein described. Dated 16 September, 1999 University of Arkansas :Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON (R:\LIBZZ]06200.doc:NJC