Apparatus and Method of Image Registration

Abstract

A method for bringing an IVUS and an OCT image into register. In one embodiment, the method includes obtaining an IVUS image of an area of a lumen; obtaining an OCT image of the same area of the lumen; determining the same asymmetry in each of the IVUS and OCT images; and overlaying the IVUS and OCT images and rotating them with respect to one another until the asymmetry in each of the IVUS and OCT images are in register, and determining the angle of rotation that resulted in the registration. In another aspect, the invention relates to a probe for OCT and IVUS imaging. In one embodiment, the probe includes a sheath having a first end and a second end defining a lumen; a marker that is opaque to light and ultrasound located between the first end and second end; and an IVUS/OCT probe head positioned within the sheath.

What is claimed is: 
     
         1 .- 23 . (canceled) 
     
     
         24 . An intravascular imaging system comprising:
 a sheath defining a lumen, a first end and a second end, the sheath having a first acoustic attenuation;   a marker comprising an optically opaque material, wherein the optically opaque material has a second acoustic attenuation, wherein the marker is positioned between the first end of the sheath and the second end of the sheath; and   a probe tip disposed within the sheath, the probe tip comprising an optical sensor and an acoustic sensor.   
     
     
         25 . The system of  claim 24  further comprising an optical fiber segment disposed in the sheath, wherein the optical sensor is a beam director, wherein the optical fiber segment is in optical communication with the beam director. 
     
     
         26 . The system of  claim 24  wherein the first acoustic attenuation and the second acoustic attenuation differ. 
     
     
         27 . The system of  claim 24  wherein the marker is a disposed on or in the sheath. 
     
     
         28 . The system of  claim 24  wherein the marker is a cylindrical annulus. 
     
     
         29 . The system of  claim 24  wherein the marker comprises a marker surface, wherein the marker surface defines a discontinuity. 
     
     
         30 . The system of  claim 28  wherein the cylindrical annulus defines a gap. 
     
     
         31 . The system of  claim 30  wherein the optical sensor and an acoustic sensor are arranged to rotate within the sheath relative to the gap such that optical signals and acoustic signals from are transmitted through the gap to each respective sensor. 
     
     
         32 . The system of  claim 24  wherein the marker is a bar positioned on or within the sheath. 
     
     
         33 . The system of  claim 24  further comprising
 an analysis and instrumentation unit comprising a processor, wherein the processor is configured to locate the marker in a plurality of intravascular images and register two or more of the plurality of intravascular images by rotating the two or more images. 
 
     
     
         34 . The system of  claim 24  further comprising
 an analysis and instrumentation unit comprising a processor, wherein the processor is configured to locate the marker in a plurality of intravascular images and determine an angle of rotation from the marker location. 
 
     
     
         35 . The system of  claim 34  wherein the angle of rotation results in two or more intravascular images being in register when one such image is rotated relative to the other such image by the angle of rotation. 
     
     
         36 . The system of  claim 33  further comprising
 a display in communication with the analysis and instrumentation unit, wherein the processor is configured to display intravascular ultrasound images and intravascular optical images registered using the marker. 
 
     
     
         37 . The system of  claim 24  wherein the optical sensor is an optical coherence tomography sensor. 
     
     
         38 . The system of  claim 24  further comprising a processor, wherein the marker defines an asymmetry, wherein the processor is configured to detect the asymmetry in a first image generated using data from the optical sensor and in a second image generated using data from the acoustic sensor. 
     
     
         39 . The system of  claim 38  wherein the processor is further configured to register the first image and the second image using the asymmetry. 
     
     
         40 . The system of  claim 24  wherein the acoustic sensor is an ultrasound transducer.