| Multi-modal optical tissue diagnostic system -> Monitor Keywords |
|
|
  Multi-modal optical tissue diagnostic systemUSPTO Application #: 20060089556Title: Multi-modal optical tissue diagnostic system Abstract: An apparatus and method according to the invention combine more than one optical modality (spectroscopic method), including but not limited to fluorescence, absorption, reflectance, polarization anisotropy, and phase modulation, to decouple morphological and biochemical changes associated with tissue changes due to disease, and thus to provide an accurate diagnosis of the tissue condition. (end of abstract) Agent: Michael B. Lasky Altera Law Group - Minneapolis, MN, US Inventors: Shabbir B. Bambot, Mark L. Faupel, Tim Harrell, Anant Agrawal USPTO Applicaton #: 20060089556 - Class: 600476000 (USPTO) Related Patent Categories: Surgery, Diagnostic Testing, Detecting Nuclear, Electromagnetic, Or Ultrasonic Radiation, Visible Light Radiation The Patent Description & Claims data below is from USPTO Patent Application 20060089556. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The invention relates to apparatus and methods for determining tissue characteristics of, for example, a human or animal. [0003] 2. Background of the Related Art [0004] Spectroscopic methods for determining tissue characteristics are known and have been widely used to interrogate changes in tissue. A number of these distinct spectroscopic techniques are available that provide specific information depending on the nature of the interaction of light with cells and the natural chromophores present in tissue. These interactions include the absorption of light at a particular wavelength, the reemission of absorbed light as fluorescence, the scattering (redirection) of light at a particular wavelength and the change in polarization between the absorbed or scattered light and the reemitted light. [0005] For example, it is known to irradiate a target tissue with electromagnetic radiation and to detect returned electromagnetic radiation to determine characteristics of the target tissue. In known methods, the amplitudes and wavelengths of the returned radiation are analyzed to determine characteristics of the target tissue. For instance, U.S. Pat. No. 4,718,417 to Kittrell et al. discloses a method for diagnosing the type of tissue within an artery, wherein a catheter is inserted into an artery and excitation light at particular wavelengths is used to illuminate the interior wall of the artery. Material or tissue within the artery wall emits fluorescent radiation in response to the excitation light. A detector detects the fluorescent radiation and analyzes the amplitudes and wavelengths of the emitted fluorescent radiation to determine whether the illuminated portion of the artery wall is normal, or covered with plaque. The contents of U.S. Pat. No. 4,718,417 are hereby incorporated by reference. [0006] U.S. Pat. No. 4,930,516 to Alfano et al. discloses a method for detecting cancerous tissue, wherein a tissue sample is illuminated with excitation light at a first wavelength, and fluorescent radiation emitted in response to the excitation light is detected. The wavelength and amplitude of the emitted fluorescent radiation are then examined to determine whether the tissue sample is cancerous or normal. Normal tissue will typically have amplitude peaks at certain known wavelengths, whereas cancerous tissue will have amplitude peaks at different wavelengths. Alternatively the spectral amplitude of normal tissue will differ from cancerous tissue at the same wavelength. The disclosure of U.S. Pat. No. 4,930,516 is hereby incorporated by reference. The above described methods are referred to as fluorescence spectroscopy. [0007] Still other patents, such as U.S. Pat. No. 5,369,496 to Alfano et al., disclose methods for determining characteristics of biological materials, wherein a target tissue is illuminated with light, and backscattered or reflected light is analyzed to determine the tissue characteristics. The contents of U.S. Pat. No. 5,369,496 are hereby incorporated by reference. This type of method is referred to as absorption spectroscopy. [0008] It is also known to look at the decay time of fluorescent emissions to determine the type or condition of an illuminated tissue. These methods are referred to as time resolved spectroscopy. Generally, apparatus for detection of the lifetime of fluorescent emissions have concentrated on directly measuring the lifetime of the fluorescent emissions. Typically, a very short burst of excitation light is directed at a target tissue, and fluorescent emissions from the target tissue are then sensed with a detector. The amplitude of the fluorescent emissions are recorded, over time, as the fluorescent emissions decay. The fluorescent emissions may be sensed at specific wavelengths, or over a range of wavelengths. The amplitude decay profile, as a function of time, is then examined to determine a property or condition of the target tissue. [0009] For instance, U.S. Pat. No. 5,562,100 to Kittrell et al. discloses a method of determining tissue characteristics that includes illuminating a target tissue with a short pulse of excitation radiation at a particular wavelength, and detecting fluorescent radiation emitted by the target tissue in response to the excitation radiation. In this method, the amplitude of the emitted radiation is recorded, over time, as the emission decays. The amplitude profile is then used to determine characteristics of the target tissue. Similarly, U.S. Parent No. 5,467,767 to Alfano et al. also discloses a method of determining whether a tissue sample includes cancerous cells, wherein the amplitude decay profile of fluorescent emissions are examined. The contents of U.S. Pat. Nos. 5,562,100 and 5,467,767 are hereby incorporated by reference. [0010] Other U.S. patents have explained that the decay time of fluorescent emissions can be indirectly measured utilizing phase shift or polarization anisotropy measurements. For instance, U.S. Pat. No. 5,624,847 to Lakowicz et al. discloses a method for determining the presence or concentration of various substances using a phase shift method. U.S. Pat. No. 5,515,864 to Zuckerman discloses a method for measuring the concentration of oxygen in blood utilizing a polarization anisotropy measurement technique. Each of these methods indirectly measure the lifetime of fluorescent emissions generated in response to excitation radiation. The contents of U.S. Pat. Nos. 5,624,847 and 5,515,864 are hereby incorporated by reference. [0011] None of the prior art methods discussed above alone is sufficient to accurately measure changes in tissue characteristics. That is, as more fully discussed below, as tissue undergoes changes from normal to, for example, cancerous tissue, fluorescence spectroscopy becomes less effective in determining tissue characteristics because it is less sensitive to the morphological changes occurring, as compared to absorption spectroscopy. Likewise, absorption spectroscopy alone is insufficient to assess changes in tissue characteristics because it is less sensitive to biochemical changes in tissue, as compared to fluorescence spectroscopy. [0012] It is known to combine two or more measurement techniques to arrive at a more accurate ultimate determination. For example, U.S. Pat. No. 5,582,168 to Samuels et al., the contents of which are hereby incorporated by reference, discloses an apparatus and method for detecting changes in the lens of an eye. Samuels et al. teach measuring both transmission or Raman or fluorescence emission, as well as scattering, reflection or similar effects. The material under examination is then normalized using a ratio of the fluorescence emission intensity to the scattering or reflected intensity. However, while this method addresses biochemical changes due to disease, it does not address morphological changes due to disease. [0013] Further, generally, prior art spectroscopic methods focus on tissue characteristics at a single point or minium number of points on the tissue. Taking measurements at just one point or a minimum number of points can be misleading as it does not provide a sufficient sampling of tissue area to accurately reflect the tissue's condition. SUMMARY OF THE INVENTION [0014] The invention focuses on providing methods and apparatus that provide accurate measurements of changes in characteristics of tissues. The methods and apparatus according to the invention combine more than one optical modality (spectroscopic method), including but not limited to fluorescence, absorption, reflectance, polarization anisotropy, and phase modulation to decouple morphological and biochemical changes associated with tissue changes, and thus to provide an accurate diagnosis of the tissue's condition. The measurements taken according to the various spectroscopic methods can be equally weighted for diagnostic purposes, or can be weighted in various manners to produce the best diagnostic results. For example, the results may be weighted based on characteristics particular to the tissue subject, such as, for example, patient ages, hormonal metabolism, mucosal viscosity, circulatory and nervous system differences. [0015] The invention encompasses apparatus and methods for determining characteristics of target tissues, wherein excitation electromagnetic radiation is used to illuminate a target tissue and electromagnetic radiation returned from the target tissue is analyzed to determine the characteristics of the target tissue. Some apparatus and methods embodying the invention can be used to perform a diagnosis at or slightly below the tissue surface of, for example, a human or animal. For instance, methods and apparatus embodying the invention could be used to diagnose the condition of skin, the lining of natural body lumens such as the gastrointestinal tract, or the surfaces of organs or blood vessels. Other apparatus and methods embodying the invention can be used to perform a diagnosis deep within tissues of, for example, a human or animal, where the excitation radiation has to pass through several centimeters of tissue before it interacts with the target tissue, such as in diagnosis of tumors and lesions deep in a breast of a human or animal. [0016] According to a preferred embodiment of the invention, an apparatus and method are provided which utilize fluorescence in combination with reflectance in order to decouple the biochemical changes from the morphological changes. The fluorescence and reflectance information may be separately analyzed and compared, or alternatively, can be calibrated to take into account the attenuation due to absorption and scattering. Other combinations of spectroscopic methods besides fluorescence and reflectance may also be appropriate. [0017] Measurements using the various spectroscopic methods may be taken simultaneously, or may be taken one after the other provided that a critical timing window, defined as the time period between the measurements, is maintained below a certain time interval. [0018] The above described techniques are preferably used to determine characteristics of multiple portions of a target tissue. The target tissue may be analyzed as a whole by simultaneously taking measurements at a plurality of interrogation points covering substantially the entire tissue surface, or by taking measurements at only a portion of the plurality of interrogation points covering substantially the entire tissue surface at timing intervals until measurements have been taken at all of the plurality of interrogation points. [0019] Further, the target tissue can be divided into a plurality of field areas to create a field pattern. Measurements may then be taken at a plurality of interrogation points within each of the field areas. The field areas may be then separately analyzed and compared in order to diagnose a condition of the target tissue. The target tissue can then be redivided into a different set of field areas and the field areas analyzed and compared in order to diagnose the condition of the tissue. The field areas may be all identically sized and/or shaped, or may have varied sizes and/or shapes. Further, the target tissue may be redivided into field areas of the same size and shape as the original field areas, which then are merely repositioned, or it may be redivided into field areas of a different size and/or shape, or of varied sizes and/or shapes. [0020] As discussed above, techniques embodying the invention can be used to determine the conditions of multiple portions of a target tissue, and the determined conditions can be used to create a map of the target tissue. Such a map could then be either displayed on a display screen, or presented in hard copy format. [0021] Further, the techniques can be used to feed information into a pattern recognition algorithm, or neural network. [0022] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims. Continue reading... Full patent description for Multi-modal optical tissue diagnostic system Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Multi-modal optical tissue diagnostic system patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Multi-modal optical tissue diagnostic system or other areas of interest. ### Previous Patent Application: Method for examining human hairs and an apparatus for implementing the method Next Patent Application: Method and apparatus to facilitate heart rate detection Industry Class: Surgery ### FreshPatents.com Support Thank you for viewing the Multi-modal optical tissue diagnostic system patent info. IP-related news and info Results in 3.43618 seconds Other interesting Feshpatents.com categories: Medical: Surgery , Surgery(2) , Surgery(3) , Drug , Drug(2) , Prosthesis , Dentistry |
||
