Detecting thermal discrepancies in vessel walls

An apparatus for analyzing infra-red radiation of a blood vessel, comprising:

• a catheter containing at least two optical fibers each having a proximal and distal end and being capable of transmitting said infra-red radiation and capable of placement of said distal end along an axis of said vessel proximate to a plaque-containing locus of an interior wall of said vessel, at least one of said fibers being a reference fiber coated on its distal end with a material that substantially prevents said optical radiation from entering said reference fiber;
• and at least one of the other of said fibers being a signal fiber whose distal end is optically connected to an optically reflective surface capable of directing infra-red radiation arising radially to said distal end of said signal fiber, into said signal fiber, said catheter including a balloon encasing said distal end of each of said fibers, said balloon being adapted for substantially limiting the flow of fluids within said vessel, and said balloon being adapted for substantially excluding said fluids between said fibers and said wall of said vessel most proximate to said locus, upon placement of said catheter inside said vessel and upon inflation of said balloon, said balloon also being capable of transmitting infra-red radiation arising from a locus or portion of said vessel wall into said fiber distal end, when said balloon is inflated and in contact with said locus during use of said apparatus;
• a guidewire slidably connected to said catheter in such a manner as to allow insertion and retraction of said catheter into and out of said vessel, upon using said apparatus;
• and
• a detector optically connected to each said proximal end of each of said fibers, and capable of receiving infra-red radiation from said proximal end arising from infra-red radiation emitted by said locus or said vessel wall, said detector comprising a multi-wavelength radiometer with a spinning circular variable filter, said filter being such that its transmission wavelength is a function of its angle of rotation and is transparent to infra-red radiation with a wavelength of approximately 3-7 micrometers, said distal ends of said reference and signal fiber being offset from one another a distance sufficient to allow sampling of infra-red radiation emitted from either fiber to pass said filter at a substantially identical position on said filter;
• said detector further comprising at least one photoelectric device capable of receiving infra-red radiation from said radiometer and converting said received infra-red radiation into an electrical signal and said detector further comprising a digitizer capable of receiving and converting said electrical signal into a digital signal;
• and
• a computer capable of receiving and mathematically fitting said digitized signal to a curve selected from a spectrum of curves for black body radiations held at preselected temperatures, said curves plotted as numbers of photons for each of said wavelengths at a preselected temperature.

A method for analyzing optical radiation of a locus in a vessel wall, comprising:

• inserting into a vessel a catheter comprising at least one fiber having a proximal and a distal end, each said fiber being capable of transmitting optical radiation, a balloon encasing a distal end of at least one said fiber and capable of transmitting optical radiation from a locus or vessel wall portion into said fiber distal end, upon contacting said locus or vessel wall portion with said balloon;
• placing at least one said fiber distal end proximate to said locus or vessel wall portion;
• inflating said balloon within said vessel to cause said balloon to limit flow of fluids within said vessel;
• receiving said transmitted radiation arising from a locus or vessel wall portion into said at least one fiber distal end;
• transmitting said radiation along said at least one fiber to a detector optically connected to said at least one fiber proximal end;
• converting transmitted radiation emerging from said proximal end, by means of said detector, into a digitized signal;
• and
• performing a computer analysis of said detector output signal whereby digitized signals from each said at least one fiber is mathematically fitted to a curve selected from a spectrum of curves for black body radiations held at preselected temperatures to detect a difference in temperature between said locus and an average temperature along said vessel wall.

A method of detecting an atherosclerotic plaque at risk of rupturing or at risk of thrombosis, comprising:

• inserting a guidewire into said vessel;
• slidingly introducing along said guidewire to a position proximate to a plaque locus of an interior wall of said vessel, a catheter comprising at least two fibers each having a proximal and distal end and being capable of transmitting infra-red radiation, a balloon encasing said distal ends, at least one of said fibers being a reference fiber coated on its distal end with a material that substantially prevents said optical radiation from entering said reference fiber, and at least one of the other of said fibers being a signal fiber whose distal end is optically connected to an optically reflective surface capable of directing optical radiation arising radially from said locus or vessel wall to said distal end of said signal fiber, into said signal fiber;
• inflating said balloon, which balloon upon inflation substantially limits the flow of fluids within said vessel, and which balloon substantially excludes said fluids between said fibers and said wall of said vessel most proximate to said locus, said balloon being capable of transmitting infra-red radiation arising from said locus or vessel wall to said fiber distal end;
• transmitting said infra-red radiation to a detector optically connected to a proximal end of each of said fibers, said detector comprising a multi-wavelength radiometer with a spinning circular variable filter, said filter being such that its transmission wavelength is a function of its angle of rotation and is transparent to radiation with a wavelength of approximately 3 to 7 micrometers, whereupon a filtered optical signal is produced, said distal ends of said reference and signal fibers being offset from one another a distance sufficient to allow sampling of radiation emitted from either fiber to pass said filter at a substantially identical position on said filter;
• converting said filtered optical signal by means of at least one photoelectric device into an electrical signal, and
• converting said electrical signal into a digitized signal by means of a digitizer;
• subtracting a digitized background signal created by said at least one reference fiber from a digitized signal transmitted by said at least one signal fiber, by means of a computer, to produce an adjusted digitized signal;
• by means of said computer, mathematically fitting said adjusted signal to a curve selected from a spectrum of curves for black body radiations held at preselected temperatures, said curves plotted as numbers of photons emitted for each of said wavelengths at a preselected temperature;
• and,
• determining if a specific plaque locus has a temperature elevated above that of vessel wall portions outside the specific locus.