Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1998-01-23
2003-07-15
Smith, Ruth S. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S342000, C600S475000, C600S478000, C600S567000
Reexamination Certificate
active
06594518
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device and method for detecting, localizing, and imaging in a radiation-scattering medium, and more particularly relates to an optical device and method for measuring information regarding the interaction of emitted light with biological tissue during passage of light through the tissue, and using said information to classify the tissue by type or state, either for detection, localization, or imaging.
BACKGROUND OF THE INVENTION
A major portion of time spent in medicine is directed toward the problem of diagnosis, and a large proportion of the errors in medicine are made here. A delayed diagnosis raises the level of pain and suffering, and may allow progression to the point of irreversibility; an incorrect diagnosis can be even worse, leading to treatment that is at best unnecessary and at worst harmful or fatal.
Medical imaging, while highly sophisticated, usually merely images body structure without classification into tissue type. For example, an X-ray shows light and dark areas, but it is up to the physician to decide what is “bone” and what is “tissue.” Thus, the classification of tissue by type is left to a human decision, or to aposteriori classification rules. A more accurate tissue-type diagnosis usually requires surgical tissue removal (such as biopsy) and subsequent analysis by a pathologist, but still this decision is based upon subjective classification by eye, touch, chemical analysis, or even upon the absorption of exogenous dyes. Currently, it is quite easy to misdiagnose many lesions, as widely different tissues (such as nerves or lymph ducts) may look similar upon first glance.
Light penetrates tissue in small amounts, particularly in wavelengths between 200 nm and 100 &mgr;m, with the best deep penetration achieved at wavelengths between 600 nm and 1200 nm. The light that does pass through tissue emerges bearing a signature of the tissue through which it passed, and this signal can be objectively analyzed. Optical methods of monitoring tissue, or invasive methods without optical diagnostics, are taught in U.S. Pat. No. 4,290,433, U.S. Pat. No. 4,622,974, U.S. Pat. No. 4,945,895, U.S. Pat. No. 5,030,207, U.S. Pat. No. 5,131,398, U.S. Pat. No. 5,271,380, and WO 92/17108. Each of these does not perform a tissue analysis, requires fluid or tissue removal or sampling, utilizes fluorescence or other emission-based techniques which measure light other than that used to perform the illumination, is restricted to external or penetrating use, or does not teach tissue classification or identification. Automated classification of tissues for general clinical use via light in vivo has not been taught, nor has such a tool been successfully commercialized.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention uses optical methods to allow for a rapid tissue diagnosis via characterization of tissue in an automated manner. The present invention relies upon the optical characteristics of tissue, either by variations in absorbance or scattering by wavelength or over space, in order to make a medical diagnosis, namely an optical classification of the tissue by tissue type or state, either as a present/absent decision, as a localization, or as an image.
A salient feature of the present invention is an incorporation of the observation that light, while both being scattered and absorbed by scattering media, can be made to penetrate human tissue, then be detected upon reemergence in order to allow quantitation of characteristics of the interior of the tissue, such as tissue types or biochemical composition, imaging and localization of tissue types, and that such information is medically useful.
Accordingly, an object of the present invention is to provide a method for detecting the presence of tissue types using light, whether to merely detect, classify, localize, or image the tissue.
A second object is that classification of the tissue can be made, wherein the classification can be selected from normal tissue types (such as artery, vein, nerve, lymph, liver, muscle, brain, gray matter, white matter, colon, blood), from tissue components (water, fat, hemoglobin), from tissue states (frozen, thawed, coagulated), from tissue functional status (alive, dead, at risk for dying), and that such classifications can even be used to determine tissue pathology (normal or abnormal).
A third object is that localization of tissue by type can be made, such that the tissue may be classified as present or absent, distances from one tissue to a reference point can be measured, or the tissue can be localized in space. A measurement that characterizes a tissue at a defined point in space is considered imaging. This spatial distribution can be key in medical diagnosis.
Another object is to provide a noninvasive method for optically detecting, quantifying, or imaging a change in the tissue state, whether to merely detect, classify, localize or image the change in the tissue. This change in state can be in response to a medical intervention, such as a change in the blood volume of the motor cortex of the brain during muscle activity, or the tool itself can initiate the change, such as by squeezing the tissue to assess vascular responsiveness, or freezing, thawing, welding, denaturing, or otherwise affecting the tissue.
Another object is that this technique is not limited to monitoring the tissue from the outside (e.g., such as is commonly done in computed x-ray tomography), but also may be used to allow a probe to measure its surrounding medium, such as if an optical fiber is inserted into a cyst, to allow sizing and diagnosis of the cyst from the inside, or if an underwater probe is to take note of objects nearby, such as rocks, when the water is cloudy, to allow better guidance. Thus, such an approach can be used both to detect changes within a medium, as well as around a probe submerged in a medium that comprises the environment of the detection apparatus. This method has the advantage of being noninvasive, should this be desired, or invasive, should measurement inside the tissue be useful. For example, the characterization of tissue as a probe is advanced through the tissue can be important in diagnosis and localization.
Another object is that any medical probe can be modified to perform this classification function, such that measurements may be made using existing medical equipment, modified to hold emitter and detector elements, such as modified hand-held medical probes, tips of surgical tools, stethoscopes, EKG leads, or other devices. The ability to classify can also be designed into new or unforeseen medical probes or devices. This function can be incorporated into replaceable device tips.
Another object is that the classification can be enhanced by a priori knowledge, such as the spectral characteristics of target tissues (which can be stored for reference in the device or in the probe), the area of the body the physician is working (such that far away tissues need not be considered in the analysis), or other medical scans (such as a CT or MRI scan).
Another object is that this data can be enhanced by collection over time. In many medical applications, the value of a measurement is enhanced by determination of temporal characteristics. For example, the detection of an enlarging bleed in head tissue holds a different significance than the detection of a stable, but otherwise similar, bleed. In underwater applications, the ability to detect moving nearby objects may also be important. Subtraction of the data at one point in time from data collected at a second point in time allows elimination of many types of individual tissue variations, and can yield improved data.
Another object is that this classification represents a decision point upon which a human response may be initiated, such as with an alarm bell, or an interlock decision may be initiated, such as via an output signal attached to a medical device.
A final object is that the detection, localization, or imaging information can be presented to the user in a number of ways,
Benaron David A.
Rubinsky Boris
Dorsey & Whitney LLP
Smith Ruth S.
LandOfFree
Device and method for classification of tissue does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device and method for classification of tissue, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device and method for classification of tissue will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3010043