Optical coupler for in vivo examination of biological tissue

Abstract

A spectrophotometric system for examination of biological tissue of interest includes a light source, a light coupling system, a light detector, and a processor. The light source is constructed and arranged to emit a light beam of visible or infra-red radiation. The light coupling sytem includes at least one mirror and is constructed and arranged to receive the emitted light beam and scan the light beam for introduction into the biological tissue of interest. The light detector is optically coupled to detect photons of radiation that have migrated over optical paths in the biological tissue of interest. The processor is operatively coupled to the light source and detector and is adapted to determine an optical property of the biological tissue of interest based on the changes between the introduced and detected radiation.

1 . An optical coupling system for non-invasively: monitoring a region of living tissue, comprising: 
 an excitation port positionable at the tissue and adapted to introduce optical radiation into the monitored tissue;    a first light guide defining an excitation channel for conveying said radiation from a source to said excitation port;    a detection port, positionable at the tissue, adapted to receive radiation that has migrated in the monitored tissue from said excitation port to said detection port, said detection port having a detection area larger than an input area of said excitation port;    a detecting light guide, connected to said detection port, for conveying said radiation from said detection port to an optical detector; and    optical matching fluid, contained within a flexible optically transparent bag, disposed partially around the monitored tissue and said excitation and detection ports.    
     
     
         2 . The optical coupling system of  claim 1  which includes multiple excitation ports positionable at the tissue and adapted to introduce radiation of said source into the monitored tissue, and multiple light guides each defining an excitation channel for conveying said radiation from said source to the corresponding excitation port.  
     
     
         3 . The optical coupling system of  claim 1  which includes multiple detection ports positionable at the tissue and adapted to receive radiation that has migrated in the monitored tissue, and multiple detecting light guides each connected to the corresponding detection port for conveying said radiation from the detection port to at least one optical detector.  
     
     
         4 . The optical coupling system of  claim 1 ,  2  or  3  wherein said optical matching fluid is positioned partially between said ports and the monitored tissue.  
     
     
         5 . The optical coupling system of  claim 1 ,  2  or  3  wherein said optical matching fluid has known scattering or absorptive properties.  
     
     
         6 . The optical coupling system of  claim 1 ,  2  or  3  further including means for changing scattering or absorptive properties of said optical matching fluid.  
     
     
         7 . The optical coupling system of  claim 6  further including means for calibrating said coupling system by controllably changing scattering or absorptive properties of said optical matching fluid.  
     
     
         8 . An optical coupler for in vivo examination of biological tissue, comprising: 
 an optical input port of a selected input area positionable on or near the examined tissue;    a first light guide optically coupled to said optical input port and constructed to transmit optical radiation of a visible or infra-red wavelength from a source to said optical input port; said optical input port being constructed and arranged to introduce said optical radiation to the examined tissue;    an optical detection port of a selected detection area positionable on or near the examined tissue, said detection port constructed and arranged to receive radiation that has migrated in the examined tissue from said input port to said detection port;    a detector light guide, optically connected to said detection port, constructed to transmit said radiation from said detection port to an optical detector; and    optical medium, disposed at least partially around the examined tissue and said input and detection ports, arranged to limit escape of, or account for photons escaped from the examined tissue.    
     
     
         9 . An optical coupling system for non-invasively monitoring a region of biological tissue, comprising: 
 a source probe including at least two optical fibers having distal ends positionable directly at the tissue, each said distal end forming an input port constructed to introduce optical radiation into the examined tissue, said fibers having proximal ends constructed and arranged to form at least one coupling port for receiving said radiation from a source; and    a detection probe including at least one optical fiber having a distal end positionable directly at the tissue, said distal end forming a detection port constructed to receive radiation that has migrated in the examined tissue, said fiber having a proximal end constructed and arranged to form at least one coupling port for conveying said detected radiation to an optical detector.    
     
     
         10 . The optical coupler of  claim 8  wherein said optical fibers include at said input port or said detection port optical matching medium arranged to achieve a desired coupling of said radiation.  
     
     
         11 . An optical coupler for in vivo examination of biological tissue, comprising: 
 an optical input port of a selected input area directed toward the examined tissue;    an optical detection port of a selected detection area directed toward the examined tissue;    optical medium disposed at least partially around the examined tissue and said input and detection ports, said optical medium being also placed between the tissue and said input area of said input port and between the tissue and said detection area of said detection port, said optical medium exhibiting known scattering or absorptive properties;    a first light guide optically coupled to said optical input port and constructed to transmit optical radiation of a visible or infra-red wavelength from a source to said optical input port; said optical input port being constructed and arranged to introduce said radiation to the optical medium;    said optical detection port constructed and arranged to receive radiation that has migrated in the examined tissue and the optical medium from said input port to said detection port; and    a detector light guide, optically coupled to said detection port, constructed to transmit said radiation from said detection port to an optical detector.    
     
     
         12 . The optical coupler of  claim 8 ,  9  or  11  wherein said optical medium has absorptive or scattering properties substantially matched to the absorptive or scattering properties of the examined tissue.  
     
     
         13 . The optical coupler of  claim 8 ,  9  or  11  further comprising an optical system constructed and arranged to alter controllably absorptive or scattering properties of said optical medium.  
     
     
         14 . The optical coupler of  claim 13  wherein said system is adapted to substantially match the absorptive or scattering properties of said optical medium to the absorptive or scattering properties of the examined tissue.  
     
     
         15 . The optical coupler of  claim 8 ,  9  or  11  further including a second input port of a selected input area, and a light guide optically coupled to said second input port, said detection port placed symmetrically relative to said first input port and said second input port.  
     
     
         16 . The optical coupler of  claim 15  wherein said input ports and said detection port are arranged in a transmission geometry.  
     
     
         17 . The optical coupler of  claim 15  wherein said input ports and said detection port are arranged in a backscattering geometry.  
     
     
         18 . The optical coupler of  claim 8 ,  9  or  11  wherein said optical ports are movable to another location relative to the examined tissue.  
     
     
         19 . The optical coupler of  claim 8 ,  9  or  11  further including multiple input ports, and multiple light guides each optically coupled to the corresponding input port.  
     
     
         20 . The optical coupler of  claim 19  wherein said multiple input ports are arranged to introduce simultaneously radiation of known time varying pattern to form resulting introduced radiation possessing a substantial gradient of photon density in at least one direction.  
     
     
         21 . The optical coupler of  claim 20  wherein said optical detection port is movable to another location relative to the examined tissue.  
     
     
         22 . The optical coupler of  claim 20  wherein said multiple input ports form a one dimensional or two dimensional array.  
     
     
         23 . The optical coupler of  claim 8 ,  9  or  11  which includes multiple detection ports, and multiple detector light guides each optically coupled to the corresponding detection port.  
     
     
         24 . The optical coupler of  claim 8 ,  9  or  11  wherein said optical medium includes a solid, liquid or gaseous medium.  
     
     
         25 . The optical coupler of  claim 8 ,  9  or  11  wherein said optical medium comprises a liquid of selectable scattering or absorptive properties.  
     
     
         26 . The optical coupler of  claim 8 ,  9  or  11  wherein said optical medium comprises a pliable solid of selectable scattering or absorptive properties.  
     
     
         27 . The optical coupler of  claim 8 ,  9  or  11  wherein said detection area of said optical detection port is larger than said input area of said optical input port.  
     
     
         28 . The optical coupler of  claim 8 ,  9  or  11  further including a port for needle localization procedure.  
     
     
         29 . The optical coupler of  claim 8 ,  9  or  11  further arranged for ultrasound examination of the tissue performed simultaneously with or subsequently to the optical examination of the tissue.  
     
     
         30 . The optical coupler of  claim 8 ,  9  or  11  further including a set of MRI coils arranged to perform an MRI examination of the tissue.  
     
     
         31 . An optical coupler for in vivo examination of biological tissue, comprising: 
 an optical input port of a first selected area directed toward the examined tissue and a second selected area oppositely oriented to said first area; said input port constructed to accept a light beam scanned over said second area and introduce said beam to the tissue at said first area;    an optical detection port of a selected detection area directed toward the examined tissue;    optical medium disposed at least partially around the examined tissue and said input and detection ports, said optical medium being also placed between the tissue and said input area of said input port and between the tissue and said detection area of said detection port, said optical medium exhibiting known scattering or absorptive properties;    said optical detection port constructed and arranged to receive radiation that has migrated in the examined tissue and the optical medium from said input port to said detection port; and    a detector light guide, optically coupled to said detection port, constructed to transmit said radiation from said detection port to an optical detector.    
     
     
         32 . The optical coupling system of  claim 31  wherein said detection area of said optical detection port comprises a multiplicity of detection subareas located at a known position of said detection area, each said detection subarea constructed and arranged to receive radiation that has migrated in the examined tissue and convey said received radiation to a detector.  
     
     
         33 . The optical coupling system of  claim 32  wherein said optical detector includes an array of semiconducting detectors each receiving light from a corresponding detection subarea via said detector light guide.  
     
     
         34 . The optical coupling system of  claim 31  wherein said light beam is scanned over said input port using a selected pattern relative to a detection sequence accumulated over said detection subareas.  
     
     
         35 . A spectrophotometric system for examination of biological tissue of interest using visible or infra-red radiation scattered over photon migration paths in the tissue, comprising: 
 a light source constructed and arranged to emit a light beam of visible or infra-red radiation;    a light coupling sytem, including at least one mirror, constructed and arranged to receive said emitted light beam, scan said received light beam and direct said scanned light beam directly into the biological tissue of interest;    a light detector optically coupled to detect photons of radiation that have migrated over optical paths in the biological tissue of interest; and    a processor, operatively coupled to said light source and detector, adapted to determine an optical property of the biological tissue of interest based on the changes between said introduced radiation in form of said directed light beam and said detected radiation that have migrated over photon migration paths in the biological tissue of interest.    
     
     
         36 . The spectrophotometric system of  claim 35  constructed and arranged as a time resolved spectrophotometric unit, wherein said light source is constructed to emit radiation comprises radiation pulses on the order of a nanosecond or less.  
     
     
         37 . The spectrophotometric system of  claim 35  constructed and arranged as a continuous wave spectrophotometer, wherein said light source is constructed to emit continuous wave, low modulation frequency radiation.  
     
     
         38 . The spectrophotometric system of  claim 35  constructed and arranged as a phase modulation spectrophotometric unit, wherein said light source is constructed to emit radiation that is modulated by a carrier waveform of a frequency on the order of 108 Hz.  
     
     
         39 . The spectrophotometric system of  claim 38 , wherein said light detector is a photomultiplier tube.  
     
     
         40 . The spectrophotometric system of  claim 35 , wherein said light includes a laser.  
     
     
         41 . The spectrophotometric system of  claim 35 , wherein said light detector includes a photomultiplier tube.  
     
     
         42 . The spectrophotometric system of  claim 35 , wherein said light detector includes a diode detector.  
     
     
         43 . A spectrophotometric system for examination of biological tissue by migration of photons scattered and absorbed over photon migration paths inside the examined tissue, comprising: 
 a laser source constructed and arranged to emit a laser beam of visible or infra-red radiation;    a rotating mirror constructed and arranged to receive said emitted light beam, and direct the laser beam into the examined biological tissue;    a light detector optically coupled to detect photons that have migrated over optical scatter paths in the examined biological tissue; and    a processor adapted to determine an optical property of the examined biological tissue based on the changes between said radiation introduced in form of said directed laser beam and said detected radiation that have migrated and scattered over photon migration paths inside the examined biological tissue.