Abstract:
Light scattering and absorption techniques for the detection of possible abnormal living tissue. Apparatus and methods for utilizing multiple blood content detection sensors and/or contact sensors for beneficially providing data to better guide an endoscope or colonoscope to locate abnormal tissue, tumors, or tissues that precede the development of such lesions or tumors.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is related to U.S. patent application Ser. No. 11/937,133, filed on Nov. 8, 2007, entitled “Blood Content Detecting Capsule.” 
     FIELD OF THE INVENTION 
     The present invention relates generally to the utilization of light scattering and absorption techniques to detect possible abnormal living tissue. More specifically, the invention relates to an apparatus and method for utilizing multiple blood content sensors to guide a probe or endoscope to more advantageously detect abnormal tissue within a living body. 
     BACKGROUND OF THE INVENTION 
     Scientists have discovered that a detectible increase in the blood content of superficial mucous membrane occurs proximate cancerous and precancerous lesions in the colon relative to the blood content of healthy tissue as described in, for example, R K Wali, H K Roy, Y L Kim, Y Liu, J L Koetsier, D P Kunte, M J Goldberg, V Turzhitsky and V Backman,  Increased Microvascular Blood Content is an Early Event in Colon Carcinogenesis , Gut Vol. 54, pp 654-660 (2005), which is incorporated by reference herein. This phenomenon is referred to as early increase in blood supply (EIBS). 
     Relying on this phenomenon, it has been discovered that it is possible to predict an area of potential abnormality based on early increase in blood supply (EIBS) in the area of abnormality. Further, it has been discovered, that by using a probe applying collimated light to an area of interest, and detecting the amount of absorbed and reflected light it is possible to provide information to a clinician to guide an endoscope to detect a possible abnormality in vivo without an invasive procedure. Such techniques have been described for example in U.S. patent application Ser. No. 11/937,133 filed on Nov. 8, 2007, entitled “Blood Content Detecting Capsule”, assigned to the assignee of the present invention, which is incorporated by reference herein. 
     However, particular types of optical blood content sensors require contact between the detection sensors and the mucosa of the underlying tissue for accurate detection of blood content. When a gap is present between these detection sensor types and the tissue of interest, a reduced amplitude of light interacted with the illuminated tissue will be received by the sensor and may be of little value in detecting abnormalities. Accordingly, in order to improve the likelihood that an abnormal area of tissue will be detected, it is important to ensure that the measurement sensor remains in contact with the tissue under investigation. Prior contemplated configurations have not addressed this issue. As a result, areas of abnormality may be missed or not detected with such systems. 
     SUMMARY OF THE INVENTION 
     The present invention advantageously increases data accuracy from detection sensors based on systems and methods that increase the desired sensor contact and/or identify collected data during the instances when such contact with the tissue under investigation occurs. This increase is accomplished in the present invention by employing, for example, contact detectors associated with the blood content detectors as part of a probe for insertion into a cavity of a living body, such as an endoscope or endoscopic sheath, and/or employing multiple blood content detectors for beneficially providing data to better guide an endoscope, colonoscope, or other probe, to locate abnormal tissue, tumors, or tissues that precede the development of such lesions or tumors. 
     In one aspect of the invention, contact detectors are employed with optical blood content detectors that provide more accurate blood content data when such sensors are in direct contact with the subject tissue. The contact detectors beneficially indicate when such sensors are in contact with tissue and correspondingly indicate that the generated blood content information signals at that instance are more likely to have improved accuracy than during instances when such sensors are not in contact with tissue. Further, the contact sensors may generate signals or power to the blood content sensors such that the illuminators and collectors within the blood content sensors are energized or powered on only during periods when the contact sensors are in contact with the tissue mucosa. 
     In another aspect of the invention, improved blood content detection is achieved by the use of multiple blood content sensors advantageously positioned in or on the surface of the probe or endoscope. The detection and locating of abnormal tissue is enhanced based on the blood detection data from the multiple sensors. It is particularly advantageous to use substantially simultaneously generated data from such sensors which can be statistically processed or otherwise to better and more accurately provide information for use in guiding the probe or endoscope. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the present invention, reference is made to the following description and accompanying drawings, while the scope of the invention is set forth in the appended claims: 
         FIG. 1  illustrates a block diagram of an exemplary system in accordance with one aspect of the invention utilizing multiple blood content detector sensors; 
         FIG. 2  illustrates an exemplary diagram of a system in accordance with the invention utilizing at least three optical blood content detectors; 
         FIG. 3  illustrates an exemplary embodiment of an optical blood content sensor useable with the present invention; 
         FIG. 4  illustrates an alternative exemplary embodiment of the optical blood content sensor useable with the present invention; 
         FIG. 5  illustrates an exemplary embodiment of a polarizer useable with the present invention; 
         FIG. 6  illustrates a representative block diagram of a exemplary processor useable with the present invention; 
         FIG. 7  illustrates an exemplary embodiment of a first endoscope configuration utilizing the present invention; 
         FIG. 8  illustrates an exemplary embodiment of a second endoscope configuration utilizing the present invention; 
         FIG. 9  illustrates an exemplary embodiment of a third endoscope configuration utilizing the present invention; 
         FIG. 10  illustrates an exemplary embodiment of a fourth endoscope configuration utilizing the present invention; 
         FIG. 11  illustrates an embodiment of an exemplary portion of an endoscope utilizing the present invention; 
         FIG. 12  illustrates an exemplary endoscope and sheath configuration utilizing the present invention; 
         FIG. 13  illustrates a second exemplary endoscope and sheath configuration utilizing the present invention; and 
         FIG. 14  illustrates an exemplary light fiber bundle useable with the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates generally to improvements in blood flow detection due to the improved contact and possibility of improved contact between the various detection sensors and the living tissue mucosa under investigation. 
     Referring to the drawings, like numbers indicate like parts throughout the views as used in the description herein, the meaning of “a” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes both “in” and “on” unless the context clearly dictates otherwise. Also, as used in the description herein, the meanings of “and” and “or” include both the conjunctive and disjunctive and may be used interchangeably unless the context clearly dictates otherwise. 
       FIG. 1  depicts a schematic diagram of blood detection system  100  containing three detection sensors. 
     However, as will be appreciated by those skilled in the art, the number of detection sensors or windows is not limited to three. Light source  1  is in contact with single fiber rod  2 . The light emanating from light source  1  is focused on the end face of single fiber rod  2 . Due to the internal configuration of single fiber rod  2 , the beams of light are repeatedly reflected off the inner walls of the single fiber&#39;s core resulting in a light source of uniform intensity, i.e., collimated light. 
     Single fiber rod  2  is further in contact with fiber bundle  3 . Fiber bundle  3  is made up of the independent illumination fibers  3   a ,  3   b ,  3   c , . . .  3   n . The transmitted light is communicated on the respective illumination fibers  3   a  to  3   n  to measurement units  12   a  to  12   n . In each measurement unit  12   a  to  12   n , the transmitted light passes through a series of polarizers, lenses and prisms before exiting. The exiting light illuminates the areas of living tissue under examination. Interacted light from the illuminated tissue mucosa is correspondingly detected by the measuring units  12   a  to  12   n . In each measurement unit  12   a  to  12   n , received interacted light passes through the measurement unit prism, lens, and polarizer as seen in  FIG. 3  and is transmitted via collectors  7   a  and  7   b  back to spectroscope  9  for analysis. 
       FIG. 2  depicts a block diagram of an exemplary configuration of the system  100  of  FIG. 1 . Referring to  FIG. 2 , the exemplary system seen in  FIG. 2  contains light source  1  for generating light of sufficient intensity and frequency to illuminate the tissue under investigation so as to ascertain the blood content within the illuminated tissue mucosa. Single fiber rod  2  may be, for example, a fiber optic conductor containing a optical core or similarly designed to equalize and collimate the light emitted from light source  1  to ensure uniform intensity and frequency of the light entering the illumination fibers. Illuminator fibers  3   a - 3   n  are individual optical transmission lines that convey the light from single fiber rod  2  to the measurement units  12   a - 12   n . Light source  1  may be, for example, a xenon lamp, a halogen, lamp, an LED, or any other light source capable of providing a light of adequate intensity and frequency. 
     In addition to light source  1 , measurement units  12   a - 12   n  further includes polarizer  4 , lens  5 , prism  6  and measurement window  15 . Polarizer  4  is a linear polarizer designed to ensue that the transmitted light waves are aligned in a linear fashion, i.e., horizontally or vertically. Lens  5  is an optical lens that conveys light waves in a parallel orientation. Light waves exit lens  5  in a generally parallel direction and strike the surface of prism  6 . Prism  6  is a optical prism with a coated reflective surface. Light waves striking the surface of prism  6  are orthogonally reflected through measurement window  15  into the underlying living tissue. Measurement window  15  is an optical window typically, glass or other transmissive material in the detection wavelength range, that does not adversely interact with or attenuate transmitted or reflected light waves. 
     Light that interacts with or is reflected off of the underlying tissue is conveyed through window  15  back through prism  6 , lens  5  and polarizer  4  onto collectors  7   a  and  7   b . Optical fibers  7   a  and  7   b  each convey the reflected light back to spectroscope processing unit (spectroscope)  9 . It should be noted that as a result of the placement of optical collectors  7   a  and  7   b  with respect to polarizer  4 , optical fibers  7   a  and  7   b  convey either horizontally or vertically polarized light waves back to spectroscope  9 . Fibers  7   a  and  7   b  enter spectroscope  9  at slot  8  and convey there respective blood content data to the data receiver located in spectroscope  9 . 
     An exemplary detailed operation of the system  100  is now described with respect to a single measurement unit  12   a  with regard to  FIGS. 1 and 2 . However, it shall be understood that this operation may be carried out simultaneously or otherwise by the measurement units  12   a - 12   n  depicted in  FIG. 1 . Referring to  FIG. 2 , light emitted from light source  1  passes through single fiber rod  2  to reach the individual optical fibers  3 . As light emanating from light source  1  passes through single fiber rod  2 , the rod  2  equalizes and collimates the intensity and wavelength of the light emitted from light source  1  and guides the equalized and collimated light into the individual illuminator fibers  3   a  to  3   n.    
     Once the collimated light enters a single fiber  3   a  to  3   n  it is communicated to the individual measurement units  12   a  to  12   n . Each measurement unit  12   a  to  12   n  is comprised of a illuminator fiber, a polarizer unit  4 , a lens  5 , a prism  6 , and window  15 . The transmitted light exits the measurement unit  12   a  via window  15  and illuminates a region of tissue within the living body. 
     Certain light interacted with the illuminated tissue is reflected back and collected by the corresponding measurement unit  12   a  to  12   n  through its corresponding window  15  and passes back through prism  6 , lens  5 , and polarizer unit  4  to the collector fibers  7   a  and  7   b.    
     Each measurement unit  12   a  to  12   n  has two optical receiving or collector fibers  7   a  and  7   b  that direct the received or collected interacted light to pass-through slit  8  in spectroscope  9  for analysis. As an alternative to the receiving fibers  7   a  and  7   b  of measurement units  12   a  to  12   n , directly entering spectroscope processing unit  9  via a slit  8 , a lens may be provided between receiving fibers  7   a  and  7   b  and the slit  8  for an improved and more efficient light transmission. An exemplary configuration for such a lens is cylindrical. However, alternative shapes or other configurations may be employed in accordance with the invention. 
     As depicted in and later described with respect to  FIG. 14 , individual fibers  3   a  to  3   n  may have a diameter as small as, for example, 100 μm, resulting in a fiber bundle  3  in  FIG. 1  as small as 1 mm. In this example, the diameter of a single fiber should likewise be of sufficient size to receive light emitted from light source  1  to produce light emitted from the various windows of a desired intensity. In order to maintain each fiber bundle  3   a - 3   n  of sufficiently small size, each individual fiber end may have a tapered shape and the area of the core at the end face close to the light source is greater than that of the other end face close to the respective single measurement unit  12   a - 12   n.    
       FIG. 3  depicts an exemplary configuration of measurement unit  12   a . Other measurement units  12   b  to  12   n  may contain similar optical configurations. Referring to  FIG. 3 , Measurement unit  12   a  contains illumination fibers, and collector fibers, linear polarizer  41  and  42 , lens  5 , prism  6 , and measurement window  15 . 
     In operation of the measurement unit of  FIG. 3 , light emitted from light source  1  (shown in  FIGS. 1 and 2 ) travels through illumination fiber  3  and passes through linear polarizer  4 . Polarizer  4  is comprised of two linear polarizers  41  and  42 . Linear polarizer  41  may be oriented for polarization in a horizontal direction and linear polarizer  42  may be oriented for polarization in a perpendicular direction relative to the linear polarization produced by polarizer  41 . The transmitted linear polarized light beams  301  pass through linear polarizer  41  and enter lens  5 . Due to the shape of lens  5 , the light beams  301  exit the lens parallel to each other before being refracted by prism  6 . The light is reflected off prism surface  21  and is conveyed through window  15  and illuminates the target tissue mucosa  17 . Prism surface  21  may contain, for example, a vapor-deposited coating of silver, aluminum, or other material in order to produce the preferred reflectivity. 
     In the instance when window  15  is in contact with the target tissue mucosa  17 , the transmitted light is interacted with by the tissue mucosa  17 . Portions of the interacted light  302  and  303  reenter prism  6  and again refracted off of the prism surface  21  and back through lens  5 . The interacted light  302  and  303  passes through lens  5  and into polarizer unit  4 , passing through either linear polarizer  41  or linear polarizer  42 . After passing through the respective polarizer  41  or  42 , the light  302  and  303  enters the respective collector fibers  7   a  or  7   b  depending on which linear polarizer  41  or  42 , the light has passed through. 
     Because of this lens, prism, and polarizer unit configuration, only light that interacts with tissue mucosa  17  at specific angles enters the collectors or receiving fibers  7   a  and  7   b . More specifically, light entering collector or receiving fiber  7   a  is oriented at the same polarization direction as the transmitted light, since both transmitted and reflected light are passing though linear polarizer  41 . In contrast, the light entering collector or receiving fiber  7   b  is always perpendicular to the transmitted light since it passes through linear polarizer  42  which is oriented in a perpendicular direction relative to that of liner polarizer  41 . 
       FIG. 4  depicts an alternative embodiment of the polarizer, lens, prism combination of measurement unit  12  of  FIG. 3 . In  FIG. 4 , the lens  5  and the prism  6  of  FIG. 3  are integrated into a single lens prism unit  19 . The integration of the two components decreases the number of sides the individual lens and prism combination has, thereby reducing the amount of stray light generated by reflection on the sides and accordingly, the stray light that reaches the light receiving fibers. A further advantage of utilizing a single lens prism combination may be realized due to the reduced number of optical components required, the reduced cost in manufacturing and assembly. In another embodiment, the flat reflection surface  21  of the prism may be spherical or ellipsoidal so as to achieve the same effect as the lens itself, thereby further reducing the number of components and manufacturing costs. 
     In operation, the measurement unit of  FIG. 4  operates in a similar manner to that described with respect to  FIG. 3 . Light emitted from light source  1  travels through illuminator fiber  3  and passes through linear polarizer  41 . Linear polarizer  41  may be oriented for polarization in a horizontal direction and linear polarizer  42  may be oriented for polarization in a perpendicular direction relative to the linear polarization produced by polarizer  41 . The transmitted linear polarized light beams  301  pass through linear polarizer  41  and enter lens prism unit  19 . Due to the shape of the lens portion of lens prism unit  19 , light beams  301  are oriented parallel to each other before being refracted by surface  21  of lens prism unit  19 . The light is reflected off surface  21  and is conveyed through window  15  and illuminates the target tissue mucosa  17 . Prism surface  21  may contain, for example, a vapor-deposited coating of silver, aluminum, or other material in order to produce the preferred reflectivity. 
     In the instance when window  15  is in contact with the target tissue mucosa  17 , the transmitted light interacts with the tissue mucosa  17 . Portions of the interacted light  302  and  303  reenter lens prism unit  19  and are again refracted off of surface  21  and back through the lens portion of lens prism unit  19 . The light  302  and  303  pass through lens prism unit  19  and into either linear polarizer  41  or linear polarizer  42 . After passing through the respective polarizer  41  or  42 , the light enters the respective collectors or receiving fibers  7   a  or  7   b , accordingly. 
     Because of the configuration of lens prism unit  19  and polarizer units  41  and  42  only light that interacts with tissue mucosa  17  at specific angles enters the collectors or receiving fibers  7   a  and  7   b . More specifically, light entering receiving fiber  7   a  is oriented at the same polarization direction as the transmitted light, since both transmitted and reflected light are passing though linear polarizer  41 . In contrast, the light entering receiving fiber  7   b  is always perpendicular to the transmitted light since it passes through linear polarizer  42  which is oriented in a perpendicular direction relative to that of liner polarizer  41 . 
       FIG. 5  depicts an exemplary configuration of the linear polarizer unit  4  of  FIGS. 2-4 .  FIG. 5  illustrates that the linear polarizers  41  and  42  of  FIGS. 2 through 4  may be composed of a glass substrate  51  with a polymer material  52  bonded to a first side and an aluminum wire vapor-deposited on an opposite, second side  53 . The polarizing surfaces i.e., polymer side or aluminum-wire side, may preferably be bonded on the surface of the light receiving fibers. Due to the thermostability of the polarizing surface, the surface is preferably formed from an aluminum wire, such as, for example, the aluminum-wire grid polarizing filter manufactured by Edmunds Optics Inc. of Barnington, N.J. 
     In the present invention, calculations are computed based on the detection of interacted light received by each individual measurement unit.  FIG. 6  shows a schematic diagram of an exemplary spectroscope  9 . In  FIG. 6 , the spectroscope  9  includes a data receiver  620 , a data preprocessor  621 , a blood content estimator  622  (or blood content calculator), a data validator  623 , a power supply  624 , an optional display or indicator  625  and a data comparator  626 . Data receiver  620  receives information from the receiving fibers  7   a  and  7   b.    
     In operation, the data received by the data receiver  620  of the spectroscope  9  in  FIG. 6  is provided to a data preprocessor  621 . The data preprocessor  621  executes, for example, a data correction algorithm, such as white correction represented in the following equation (1). 
     
       
         
           
             
               
                 
                   
                     Δ 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     
                       Ic 
                       ⁡ 
                       
                         ( 
                         λ 
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                         Δ 
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                         ⁢ 
                         
                           I 
                           ⁡ 
                           
                             ( 
                             λ 
                             ) 
                           
                         
                       
                       
                         Δ 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         
                           Iw 
                           ⁡ 
                           
                             ( 
                             λ 
                             ) 
                           
                         
                       
                     
                     = 
                     
                       
                         
                           
                             I 
                             Π 
                           
                           ⁡ 
                           
                             ( 
                             λ 
                             ) 
                           
                         
                         - 
                         
                           
                             I 
                             ⊥ 
                           
                           ⁡ 
                           
                             ( 
                             λ 
                             ) 
                           
                         
                       
                       
                         
                           
                             Iw 
                             Π 
                           
                           ⁡ 
                           
                             ( 
                             λ 
                             ) 
                           
                         
                         + 
                         
                           
                             I 
                             ⊥ 
                           
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     Where the symbols Π and ⊥ used in the numerator and denominator of equation (1) represent the spectrum of horizontally polarized light and the spectrum of vertically polarized light, respectively. In equation (1), Λ represents wavelength, ΔI(λ) indicates the measured difference polarization spectrum, ΔIw(λ) is the spectrum measured using a standard white plate and is calculated by summing the white horizontal polarization spectrum Iw Π (λ) and the white perpendicular polarization spectrum Iw ⊥ (λ), as shown in the denominator of equation (1). In the numerator of equation (1), the difference between the horizontal polarization spectrum I Π (λ) and the perpendicular polarization spectrum I ⊥ (λ) is calculated and a signal indicative of ΔI(λ). 
     Based on the generated results of the data processor  621 , the blood content estimator  622  calculates the blood content by using equation (2) below, which is shown in, for example, M. P. Siegel et al.  Assessment of blood supply in superficial tissue by polarization - gated elastic light - scattering spectroscopy , Applied Optics, Vol. 45, Issue 2, pp. 335-342 (2006), which is incorporated by reference herein.
 
Δ I (λ)=Δ I   scattering (λ)exp[−α A   PG (λ)]  (2)
 
     The blood content estimator  622  calculates the blood quantity by using a model equation, such as equation (2), and may provide a corresponding blood content value to optional display  625 . Alternatively, the blood content estimator  622  may also provide the blood content value to data validator  623  as a check on the integrity of the collected data. Further, blood content estimator  622  may provide the results from the various detection units to comparator unit  626  to determine the validity of a measurement and to improve the accuracy of detection based on the numerous measurement units. 
     Various configurations of exemplary endoscopes with multiple measurement units in accordance with the invention are depicted in  FIGS. 7 to 13 . More specifically,  FIG. 7  depicts an endoscope tip  71  with multiple measurement units. Endoscope tip  71  is generally concave in shape with the multiple measuring units  72  deployed along the concave surface of the tip. In operation, by pressing an endoscope tip  71  into living tissue, the tissue is drawn into, or aspirated into contact with the multiple measuring units  72 . The placement of numerous measurement units on the concave surface ensures contact by one or more of the measurement units. Contact with multiple measurement units would tend to provide a more accurate reading than a probe with a single measurement unit. In additional, greater accuracy in blood content detection is achievable by comparing the data obtained from the multiple measuring units  72 . 
     In the configuration of  FIG. 8  multiple measurement units  84  are employed with a traditional flexible endoscope  8 . Endoscope  8  contains a rigid tip  81 , a connecting portion  82 , angled portion  83 , and measurement units  84  in accordance with the invention. By placing the measurement units  84  on the outer circumference of the insertion portion of the flexible endoscope, the detection windows are advantageously more likely to contact the tissue mucosa upon insertion and removal of the device. 
       FIG. 9  depicts a variation of the configuration of the invention shown in  FIG. 8 . A second ring of detection units  184  is longitudinally located on the circumference of the connecting portion  82 . By utilizing a second ring of measurement units  184  on the circumference of the flexible endoscope, a user is able to obtain measurement results at two different locations along the longitudinal access of the endoscope. By analyzing the data from the two different regions on the living tissue, an operator can more accurately determine the proximity of the abnormal lesion by utilizing the differences between the two areas of measurement. 
       FIG. 10  depicts an alternative embodiment to those disclosed in  FIGS. 8 and 9 . As seen in  FIG. 10 , the measurement units  184  may be arranged in a substantially helical arrangement about the circumference of the insertion portion of a flexible endoscope. Such an arrangement significantly increases the coverage area of the multiple detection windows. 
       FIG. 11  depicts an embodiment of the present invention wherein the connecting portion of the endoscope has a thread-like or helical protruded portion  112 . In this embodiment, the multiple measurement units  111  are placed in the outer circumference of the helical protrusion  112 . In operation of this configuration, the multiple measurement units  111  tend to serially come into contact with the same areas of tissue mucosa as the insertion portion is rotated upon insertion or extraction. 
       FIG. 12  depicts an endoscope  122  covered by a sheath  121  with measurement units  123  disposed therein. Sheath  121  is essentially a tube into which, for example, an endoscope  122 , such as a conventional endoscope is inserted. Multiple measurement units  123  are arranged along the circumference of sheath  121  and contact living tissue mucosa  124 . This type of sheath configuration allows the user to employ a conventional endoscope while at the same time advantageously utilizing blood content detection methods for guiding the endoscope to abnormal tissue. It will be appreciated by one skilled in the art that sheath  121  may also be configured with the thread-like protrusions  112  and the multiple measurement units  123  may likewise be configured in a spiral configuration along the circumference of the thread-like shape. 
       FIG. 13  depicts an embodiment with sheath  131 , endoscope  132 , and balloon  133  having multiple measurement units  134  disposed therein. Sheath  131  is typically a hollow tube through which, for example, a endoscope  132  will be inserted. Balloon  133  is attached to or formed integral with the sheath  131  and is inflated by either air or water pressure. Upon placement of sheath  131 , balloon  133  is inflated to contact the target tissue mucosa  135 . The inflation of balloon  133  ensures contact between the multiple measurement units  134  and tissue mucosa  135 . Further, a sensor  136  may be employed to start the blood detection process based on inflation of balloon  133 . As will be appreciated by those skilled in the art, sensor  136  may be located internally or externally to the sheath  131  or balloon  133 . For example a sensor could be located on the surface of balloon  136  or within sheath  131  and may sense the back pressure exerted by the balloon  133  when it inflates and contacts living tissue  135 . 
     In an alternative embodiment, two or more balloons may be utilized, each with its own set of measurement units  134 . By utilizing multiple balloons  133 , the multiple measurement units  134  can be spread out along sheath  131 . In the manner, the blood content detection data can be analyzed to determine which of the balloons  133  is closest to an area of interest. Such information will aid in isolating and detecting potential areas of interest. 
     In another exemplary embodiment of the present invention, blood data collection is triggered upon the sensing of contact between balloon  133  and tissue mucosa  135 . Such sensing of contact may be the result of back pressure sensed in the balloon inflation mechanism or as a result of surface sensors  136  located in balloon  133 . 
     While the foregoing description and drawings represent the preferred embodiments of the present invention, it will be understood that various changes and modifications may be made without departing from the spirit and scope of the present invention. For example, although the improved method and apparatus described herein as part of or in conjunction with an endoscope, it is also possible to use the invention with a stand alone probe or other medical device.