High speed elastrographic property mapping of lumens utilizing micropalpation delivered from an oct-equipped catheter tip

Abstract

A method for performing elastographic deformation mapping of tissues and plaques comprises: introducing a distal portion of a catheter to an interior of an interior body of a patient; applying, from a palpator in the distal portion, one of a directed fluid or a mechanical indenter to produce a surface-applied palpation force to a target area of the interior body to mechanically displace the interior body and cause elastographic deformation of the target area of one or more surface and subsurface tissues and plaques; and directing and delivering an OCT (optical coherence tomography) beam, from an OCT imaging sensor in the distal portion, for OCT deformation detection including elastographic deformation measurement to provide elastographic mapping of the target area.

What is claimed is: 
     
         1 . A method for performing elastographic deformation mapping of tissues and plaques, the method comprising:
 introducing a distal portion of a catheter to an interior of an interior body of a patient, the catheter including an elongated catheter body extending longitudinally between a proximal end and a distal end along a longitudinal axis, the catheter body including the distal portion at the distal end and a catheter lumen from the proximal end to the distal end;   producing, from a palpator in the distal portion, a KHz or faster directed pulsed fluid jet and associated shockwave in the distal portion directed toward a target area of tissue surface of the interior body to mechanically displace the interior body tissue surface and cause pulsed elastographic deformation of the target area of one or more surface or subsurface tissues or plaques by one of:   (i) emitting the jet using a transducer to displace a fluid in the distal portion and emit the fluid out of an orifice, or   (ii) emitting the jet using pulsed microbubble formation in a fluid to displace the fluid in the distal portion and emit the fluid out of an orifice; and   directing and delivering an OCT (optical coherence tomography) beam, from an OCT imaging sensor in the distal portion, for OCT deformation detection including elastographic deformation measurement to provide elastographic mapping of the target area.   
     
     
         2 . The method of  claim 1 ,
 wherein (ii) the pulsed microbubble formation comprises providing in the distal portion a thermal microbubble driven emitter as the palpator to explosively evaporate the fluid to create one or more microbubbles at bubble growth rates that are fast enough to produce shock waves and pronounced pressure spikes, which cause emission of some of the fluid from the thermal microbubble driven emitter to produce palpating shockwaves from the distal portion toward the target area of tissue surface of the interior body.   
     
     
         3 . The method of  claim 1 ,
 wherein (i) using the transducer to displace the fluid comprises generating pulse pressure in the distal portion to produce pulsed fluid palpation to apply the directed pulsed fluid jet for a sustained period in the order of milliseconds to tenths of a second.   
     
     
         4 . The method of  claim 1 ,
 wherein (i) using the transducer to displace the fluid comprises electrically actuating a positive displacement transducer to bend in shear mode as the palpator in the distal portion.   
     
     
         5 . The method of  claim 1 ,
 wherein the directed pulsed fluid jet produces a palpation force having a palpation force vector, and the palpation force vector and the OCT beam are substantially concentric.   
     
     
         6 . The method of  claim 1 , further comprising:
 producing at least one pair of palpation forces, from the directed pulsed fluid jet applied from the distal portion, each pair being in opposite directions.   
     
     
         7 . The method of  claim 1 , further comprising:
 providing a closed balloon around the distal portion, filling the closed balloon with a liquid that is transparent to OCT wavelengths, and inflating the closed balloon against a surface of the interior body.   
     
     
         8 . The method of  claim 7 ,
 wherein the directed pulsed fluid jet is produced, and the OCT beam is directed and delivered, through a balloon wall of the balloon.   
     
     
         9 . The method of  claim 1 , further comprising:
 synchronizing a palpation force produced by the directed pulsed fluid jet and the OCT beam to perform OCT deformation detection including elastographic deformation measurement to provide elastographic mapping of the one or more surface or subsurface tissues or plaques.   
     
     
         10 . The method of  claim 1 , wherein directing and delivering the OCT beam for OCT deformation detection produces optical spectroscopic information including elastographic deformation measurement, the method further comprising:
 implementing an additional optical analytical modality utilizing at least some common portion of the OCT beam's optical path to produce additional optical spectroscopic information.   
     
     
         11 . The method of  claim 10 , further comprising:
 providing compositional mapping of the target area using both the elastographic deformation measurement and the additional optical spectroscopic information in combination.   
     
     
         12 . The method of  claim 1 , further comprising:
 rotating the palpator and the OCT imaging sensor around the longitudinal axis of the catheter body to change orientation of the OCT beam and a palpation force produced by the directed pulsed fluid jet to be directed to different target areas of tissue surface of the interior body.   
     
     
         13 . The method of  claim 12 , further comprising:
 axially translating the palpator and the OCT imaging sensor along the longitudinal axis of the catheter body to change orientation of the OCT beam and the palpation force to be directed to different target areas of tissue surface of the interior body.   
     
     
         14 . The method of  claim 12 , further comprising:
 providing three dimensional mapping of the one or more surface or subsurface tissues or plaques of the interior body based on OCT deformation detection including elastographic deformation measurement by the OCT imaging sensor of the different target areas of tissue surface of the interior body.   
     
     
         15 . An optical coherence tomography (OCT) catheter for performing elastographic deformation mapping of tissues and plaques of an interior body, the OCT catheter comprising:
 a catheter having an elongated catheter body extending longitudinally between a proximal end and a distal end along a longitudinal axis, the catheter body including a distal portion at the distal end and a catheter lumen from the proximal end to the distal end;   a palpator, disposed in the distal portion, to produce a KHz or faster directed pulsed fluid jet and associated shockwave in the distal portion and emit the jet from the distal portion directed toward a target area of tissue surface of the interior body to mechanically displace the interior body tissue surface and cause pulsed elastographic deformation of the target area of one or more surface or subsurface tissues or plaques, the palpator comprising (i) a transducer to displace a fluid in the distal portion and emit the fluid out of an orifice, or (ii) a thermal microbubble driven emitter to produce pulsed microbubble formation in a fluid to displace the fluid in the distal portion and emit the fluid out of an orifice; and   an OCT imaging sensor, disposed in the distal portion, to direct and deliver an OCT beam for OCT deformation detection including elastographic deformation measurement to provide elastographic mapping of the target area.   
     
     
         16 . The OCT catheter of  claim 15 , wherein the palpator comprises:
 (ii) the thermal microbubble driven emitter to explosively evaporate the fluid to create one or more microbubbles at bubble growth rates that are fast enough to produce shock waves and pronounced pressure spikes, which cause emission of some of the fluid from the thermal microbubble driven emitter to produce palpating shockwaves from the distal portion toward the target area of tissue surface of the interior body.   
     
     
         17 . The OCT catheter of  claim 15 , wherein the palpator comprises:
 (i) the transducer to generate pulse pressure in the distal portion to produce pulsed fluid palpation to apply the directed pulsed fluid jet for a sustained period in the order of milliseconds to tenths of a second.   
     
     
         18 . The OCT catheter of  claim 15 , wherein the palpator comprises:
 (i) the transducer which is a positive displacement transducer that is electrically actuated to bend in shear mode.   
     
     
         19 . The OCT catheter of  claim 15 , further comprising:
 a closed balloon disposed around the distal portion and being filled with a liquid that is transparent to OCT wavelengths;   wherein the closed balloon is inflatable against a surface of the interior body.   
     
     
         20 . The OCT catheter of  claim 19 ,
 wherein palpation by the palpator and elastographic mapping by the OCT imaging sensor are performed through a balloon wall of the balloon.   
     
     
         21 . The OCT catheter of  claim 15 , further comprising:
 an acoustic imaging sensor, disposed in the distal portion, to provide ultrasonic imaging of the target area, the acoustic imaging sensor including one or more openings or channels;   wherein the directed pulsed fluid jet produced by the palpator passes through the one or more openings or channels of the acoustic imaging sensor to the target area of tissue surface of the interior body.