Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Patent
1997-08-06
1998-11-24
Casler, Brian
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
A61B 600
Patent
active
058400354
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a method for spectroscopic examination of biological tissue.
2. Description of the Prior Art
The diagnosis of mammary carcinoma is currently mainly based on the imaging method of X-ray mammography. Portions of the public and of the medical community, however, are increasingly critical of this examination method since damage to the transirradiated tissue cannot be precluded with certainty. Additionally utilized, further, is the extremely complicated nuclear magnetic resonance tomography as well as, to a slight extent, ultrasound measuring methods and infrared thermography.
Light-tomographic methods are being clinically tested wherein to tissue to be examined is illuminated with visible or, respectively, IR light and the reflected or transmitted radiation is detected (see, for example, G. Muller et al. (Eds.), Medical Optical Tomography. Functional Imaging and Bellingham, Wash., 1993, SPIE Vol. IS11; B. Chance, R. R. Alfano, A. Katzir (Eds.) Photon Migration and Imaging in Random Media and Tissues, The International Institute for Optical Engineering, Bellingham, Wash. 1993, SPIE Vol. 1988; G A Navarro, A. E. Profio; Med. Phys. Vol. 15(1988); S. 181-187. Since the measured intensities are dependent on the optical properties of the respectively transirradiated region, one hopes to be able to distinguish tissue types and identify and localize physiological or, respectively, pathological modifications in the tissue. Possible applications of light-tomography extend from the detection of mammary carcinoma via the recognition of Alzheimer's disease up to the registration of the oxygenation of the brain and the extremities.
SUMMARY OF THE INVENTION
An object of the invention is to create an optical method with which physiological and pathological modifications in a biological tissue, particularly in the human body, can be detected in vivo. The method should not produce any damage to the tissue and should be comparatively simple to implement without great apparatus outlay.
The above object is achieved in a method for spectroscopic examination of a biological tissue wherein the tissue is irradiated with light having an intensity l.sub.0 (.lambda.) with the wavelength .lambda. being varied, a transmission or reflection spectrum l(.lambda.) is obtained by measuring the intensity of the radiation transmitted or reflected by the tissue dependent on the wavelength .lambda., and an approximate description of the measured transmission or reflection spectrum l(.lambda.) or of the spectrum l(.lambda.)/l.sub.0 (.lambda.) normalized to the incident radiation intensity, or of the quantity log {l(.lambda.)/l.sub.0 (.lambda.)} with an analytical function is made. The analytical function has a Beer-Lambert dependency on a first parameter which describes the absorption properties of the tissue and has a second parameter which is the average path length L(.lambda.) of the photons in the tissue, representing a slice thickness. The first parameter is dependent on concentrations c.sub.i of a number i of selected tissue components which are employed as fit parameters, as well as being dependent on specific absorption coefficients .alpha..sub.i (.lambda.) according to the relationship ##EQU2## The identified concentrations c.sub.1 are then compared to reference values.
The method is preferably employed in the area of medical diagnostics. Due to its enhanced sensitivity or, respectively, selectivity compared to what is referred to as diaphanography (see, for example, /3/), regions with pathological tissue modifications can be distinguished better from surrounding, healthy tissue and carcinoma in the female breast can be more exactly localized.
DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 show the absorption coefficients of hemoglobin (H.sub.b), oxyhemoglobin (H.sub.b O), water and fat (vegetable oil) dependent on wavelength.
FIG. 3 shows the reduced scatter coefficient of breast tissue (in vivo) dependent on the wavelength.
FIG. 4 is a schematic i
REFERENCES:
patent: 4655225 (1987-04-01), Dahne et al.
patent: 4768516 (1988-09-01), Stoddart et al.
patent: 4805623 (1989-02-01), Jobsis
patent: 5099123 (1992-03-01), Harjunmaa
patent: 5112124 (1992-05-01), Harjunmaa et al.
patent: 5119815 (1992-06-01), Chance
patent: 5293873 (1994-03-01), Fang
patent: 5492118 (1996-02-01), Gratton et al.
Farrell et al., A diffusion theory model of spatially resolved, steady state difuse reflectance for the noninvasive determination of tissue optical properties in vivo, Med. Phys. 19(4), Jul./Aug, pp. 879-888, 1992.
Patterson et al., Time resolved reflectance and transmittance for the non-invasive measurement of tissue optical properties, Applied Optics, vol. 28, No. 12, pp. 2331-2336, Jun. 15, 1989.
Delori et al., Spectral reflectance of the human ocular funds, Applied Optics, vol. 28, No. 6, pp. 1061-1077, Mar. 15, 1989.
"Breast Tumor Characterization Using Near-Infra-Red Spectroscopy, " Kang et al., SPIE, vol. 1888, pp. 487-499.
"Contrast in Diaphanography of the Breast," Navarro et al., Med. Phys. 15 (2), Mar./Apr. 1988, pp. 181-187.
"A Comprehensive Approach To Breast Cancer Detection Using Light: Photon Localization By Ultrasound Modulation and Tissue Characterization by Spectral Discrimination," Marks et al., SPIE, vol. 188, pp. 500-511.
"Introduction: A Medical Perspective at the Threshold of Clinical Optical Tomography," Benaron et al., Medical Optical Tomography. Functional Imaging and Monitoring, The International Institute for Optical Engineering, SPIE, vol. IS11 (1993).
"Time Resolved Reflectance and Transmittance for the Non-invasive Measurement of Tissue Optical Properties," Patterson et al., Applied Optics, vol. 28, No. 12, Jun. 15, 1989, pp. 2331-2335.
"Spectral Reflectance of the Human Ocular Fundus," Delori et al., Applied Optics, vol. 28, No. 6, Mar. 15, 1989, pp. 1061-1077.
"A Diffusion Theory Model of Spatially Resolved, Steady-state Diffuse Reflectance for the Noninvasive Determination of Tissue Optical Properties in vivo" Farrell et al., Med. Phys. vol. 19, No. 4, Jul./Aug. 1992, pp. 879-888.
Heusmann Hans
Kolzer Jochen
Casler Brian
Siemens Aktiengesellschaft
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