Optical techniques for examination of biological tissue

Claim 2

A spectroscopic method for examination of biological tissue of a subject, comprising the steps of: providing a source of electromagnetic radiation of a visible or infrared wavelength selected to be scattered and absorbed while migrating in the tissue, said source being optically coupled to an input port, and providing at least two detection ports optically coupled to at least one detector, said detector connected to a detector circuit constructed to provide detection signals of known sensitivity; positioning said input port relative to a selected input location of the tissue; positioning a first detection port and a second detection port relative to selected first and second detection locations of the examined tissue, said input and detection locations and said sensitivity defining a null plane in the tissue and defining a volume of the examined tissue of the subject; introducing into the tissue, at said input location located on said null plane, radiation of a selected intensity; detecting, at said first detection location, radiation that has migrated in the examined tissue from said input location and providing, by said detector circuit, a first detection signal corresponding to said detected radiation; detecting, at said second detection location, radiation that has migrated in the examined tissue from said input location and providing by said detector circuit, a second detection signal corresponding to said detected radiation; subtracting said first detection signal from said second detection signal to obtain processed data; and examining a property of said tissue volume using said processed data.

Claim 3

The spectroscopic method of claim 1 wherein said first detection signal and said second detection signal are stored and subtracted in an analog form by said detection circuit.

Claim 4

The spectroscopic method of claim 1 further comprising, converting said first and second detection signals to a digital form, said subtracting step being performed digitally on said first detection signal and said second detection signal in a digital circuit.

Claim 5

The spectroscopic method of claim 1 wherein said steps of positioning said input and detection ports at the respective selected locations include placing said ports on the surface of the examined tissue.

Claim 6

The spectroscopic method of claim 4 wherein said orienting said input ports includes directing an optical element of said port to said location.

Claim 7

The spectroscopic method of claim 1 wherein said steps of positioning said input and detection ports include orienting said ports relative to said input and detection locations.

Claim 8

The spectroscopic method of claim 1 wherein said positioning steps are performed in a manner that sweeps said null plane by moving said detection ports over at least a portion of said volume of the examined tissue.

Claim 9

The spectroscopic method of claim 1 wherein said detecting steps are performed in a manner that changes the relative sensitivity of detection at said first and second detection ports in order to sweep said null plane over at least a portion of said volume of the examined tissue and said method further comprising, simultaneously with said sweeping, positioning said input port at input locations corresponding to said swept null plane.

Claim 10

The spectroscopic method of claim 1 further comprising finding, in said tissue volume, a tissue region exhibiting different scattering or absorptive properties than the rest of the examined tissue volume.

Claim 11

The spectroscopic method of claim 9 further comprising imaging the examined tissue including said tissue region of different scattering or absorptive properties.

Claim 12

The spectroscopic method of claim 1 further comprising displaying an image of the examined tissue by utilizing said processed data and relative locations of said input ports and said output ports.

Claim 13

The spectroscopic method of claim 1 further comprising a step of introducing an exogenous pigment into the tissue, said selected wavelength being sensitive to said pigment.

Claim 14

The spectroscopic method of claim 12 wherein said exogenous pigment is preferentially accumulated in a tissue region exhibiting different scattering or absorptive properties.

Claim 15

The spectroscopic method of claim 12 wherein said exogenous pigment is a fluorescing pigment when irradiated by a selected wavelength, and said detecting steps include detecting preferentially a radiation wavelength of said fluorescing pigment.

Claim 16

A spectroscopic system for examination of biological tissue of a subject, comprising: a source of electromagnetic radiation of a visible of infrared wavelength; an input port, optically coupled to said light source, constructed to introduce said radiation at a selected input location of the examined tissue; a detector optically coupled to at least two detection ports located relative to selected first and second detection locations, respectively; a detector circuit connected to and receiving a signal from said detector and constructed to provide a detection signal of known sensitivity said detector circuit including a sample-and-hold circuit and a subtraction circuit: said locations and said sensitivity defining a null plane in the examined tissue and defining a volume of the examined tissue, said detector constructed to detect radiation that has migrated in the examined tissue to said detection ports; said detector circuit constructed to correlate emission of said radiation from said input port with detection of first detected radiation scattered and absorbed while migrating in the tissue to said first detection location, said first detected radiation being stored as a first detection signal; said detector circuit further constructed to correlate emission of said radiation from said input port with detection of second detected radiation scattered and absorbed while migrating in the tissue to said second detection location, said second detected radiation being stored as a second detection signal; said subtraction circuit constructed to subtract said first detection signal from said second detection signal; and a processor, connected to and receiving said processed data from said subtraction circuit, constructed to evaluate properties of the examined tissue.

Claim 17

A spectroscopic system for examination of biological tissue of a subject, comprising: a source of electromagnetic radiation of a visible of infrared wavelength; an input port, optically coupled to said light source, constructed to introduce said radiation at a selected input location of the examined tissue; a detector optically coupled to at least two detection ports located relative to selected first and second detection locations, respectively; a detector circuit connected to and receiving a signal from said detector and constructed to provide a detection signal of known sensitivity said detector circuit including a sample-and-hold circuit and a subtraction circuit: said locations and said sensitivity defining a null plane in the examined tissue and defining a volume of the examined tissue, said detector constructed to detect radiation that has migrated in the examined tissue to said detection ports; said detector circuit constructed to correlate emission of said radiation from said input port with detection of first detected radiation scattered and absorbed while migrating in the tissue to said first detection location, said first detected radiation being stored as a first detection signal; said detector circuit further constructed to correlate emission of said radiation from said input port with detection of second detected radiation scattered and absorbed while migrating in the tissue to said second detection location, said second detected radiation being stored as a second detection signal; said subtraction circuit constructed to subtract said first detection signal from said second detection signal; and a processor, connected to and receiving said processed data from said subtraction circuit, constructed to evaluate properties of the examined tissue.

Claim 18

A spectroscopic system of claim 15 further comprising a detector controller constructed to change the relative sensitivity of detection at said first and second detection ports in order to sweep said null plane over at least a portion of said volume of the examined tissue.

Claim 19

A spectroscopic system of claim 16 further comprising a positioner constructed to displace said input port to a selected location.

Claim 20

A spectroscopic system of claim 15 wherein said detection ports are arranged in a linear array.

Claim 21

A spectroscopic system of claim 15 wherein said detection ports are arranged in a two dimensional array.

Claim 22

A spectroscopic system of claim 15 further comprising an image processor connected to receive said processed data from said processor and create image data; and a display, connected to said image processor, constructed to display said image data representing the examined tissue.

Claim 23

A spectroscopic system of claim 20 wherein said image processor is further constructed to create image data of said located tissue region exhibiting different scattering or absorptive properties; and said display is constructed to display said image data.

Claim 24

A spectroscopic system of claim 15 wherein said processor is further constructed to locate, in said tissue volume, a tissue region exhibiting different scattering or absorptive properties than the rest of the examined tissue volume.

Claim 25

A spectroscopic system of claim 15 wherein said wavelength is sensitive to an endogenous pigment of the examined tissue.

Claim 26

A spectroscopic system of claim 15 wherein said wavelength is sensitive to an exogenous pigment of the examined tissue.