Apparatus, systems, and methods for mapping of tissue oxygenation

Abstract

Apparatus, systems, and methods are provided that generate in vivo maps of oxygenation measurements of biological tissue. These may include surgical instruments and stand-alone imaging systems with incorporated oxygen sensing capability. Oxygenation maps can be determined via fluorescent or phosphorescent lifetime imaging of an injectable probe with an oxygen-dependent optical response. Probe configuration and methods and apparatus of injecting the probe into the tissue are provided. Methods and apparatus for temperature compensation of temperature-dependent lifetime measurements are provided to improve oxygenation measurement accuracy. Oxygen maps may be registered with visible light images to assist in assessing tissue viability or localize anomalies in the tissue. Resulting oxygen images may be used for various applications including, but not limited to, guiding surgical procedures such as colorectal resection through use of intraoperative sensing, enhanced endoscopic imaging for identifying suspect lesions during colonoscopy, and external imaging of tissue such as assessing peripheral vascular disease.

1 . An imaging system that resolves and maps a physiologic condition, or proxy thereof; the imaging system utilizing information obtained from two or more sensing modalities to resolve said physiologic condition or proxy thereof; the sensing modalities used in conjunction provide improved accuracy of absolute measurements of said physiologic condition or measurement. 
     
     
         2 . The imaging system of  claim 1 , wherein one sensing modality assesses the phosphorescent and/or fluorescent lifetime associated with a medium and another sensing modality assesses temperature at or near said medium. 
     
     
         3 . The imaging system of  claim 2 , wherein the medium comprises a probe with a phosphorescent lifetime that relates to nearby oxygen concentration and the temperature measurement is used to compensate for variations in the temperature-dependent calibration coefficient of the probe's lifetime to oxygenation. 
     
     
         4 . The imaging system of  claim 1 , wherein system comprises:
 an optical sensor configured for detecting the lifetime of the decay of a phosphorescent and/or fluorescent medium after it is externally illuminated,   a temperature sensor for detecting the temperature at one or more points in the field of view of said optical sensor, and   a processor configured to use temperature measurement to compensate for temperature-dependent lifetime variation of the medium.   
     
     
         5 . The imaging system of  claim 2 , wherein one modality is configured for phosphorescent lifetime imaging, wherein the system comprises both an optical detector for mapping phosphorescent lifetime and an optical detector for detecting temperature; the system configured to register the temperature and lifetime images, and utilizing both phosphorescent lifetime and temperature at each mapped point to determine the corresponding oxygenation. 
     
     
         6 . An endoscopic imaging system configured to sense oxygenation and generate a map of said oxygenation based on phosphorescent lifetime of an injectable probe. 
     
     
         7 . The imaging system of  claim 6  further comprises a sensor to detect temperature in a region corresponding to the map of oxygenation, wherein the imaging system is configured to compensate for temperature-dependent oxygenation measurements based on thermal measurements. 
     
     
         8 . The endoscopic imaging system of  claim 6 , wherein a secondary imaging scope is configured for sensing oxygenation; said secondary imaging scope operates independently from a primary scope, and operates in conjunction with said primary scope. 
     
     
         9 . The endoscopic imaging system of  claim 8 , wherein the primary scope is a flexible endoscope, and the secondary scope is configured to pass through the instrument port of said endoscope. 
     
     
         10 . The imaging system of  claim 8 , wherein the system is configured to register video images and said oxygenation maps, and further the system is configured to display the video images with an overlay of said oxygenation maps. 
     
     
         11 . The invention system of  claim 10 , wherein the system tracks features and maintains alignment of an acquired oxygen map after removal of, or disabling of, the secondary imaging scope configured for sensing oxygenation. 
     
     
         12 . The imaging system of  claim 6 , wherein the system is configured to selectively excite a phosphorescent response in tissue, wherein said selective excitation provides a means for uniquely identifying oxygenation associated with a layer or depth of tissue. 
     
     
         13 . The imaging system of  claim 12 , comprising a light source attached at the tip of an extension arm, said arm capable of selectively illuminating a region or layer of tissue. 
     
     
         14 . A method, comprising the steps of: registering oxygenation maps or their corresponding precursor lifetime maps to thermal images, and utilizing said registered information to compensate for temperature-dependent variation in oxygenation measurements. 
     
     
         15 . The method of  claim 14 , wherein images from multiple cameras are acquired using near infrared illumination; said near infrared illumination being detectable with a visible light endoscopy camera, and a camera configured to detect a phosphorescent or fluorescent response; and mutual information between the images from the multiple cameras is used for registration. 
     
     
         16 . The method of  claim 14 , further comprising the step of mapping tissue oxygenation of the intestinal wall. 
     
     
         17 . The method of  claim 16 , further comprising the step of distinguishing lesions from healthy intestinal wall tissue. 
     
     
         18 . The method of  claim 17 , further comprising the step of distinguishing polyps based on pattern matching of static images of phosphorescent lifetime or oxygenation. 
     
     
         19 . The method of  claim 18 , further comprising the step of distinguishing polyps based on dynamic changes of a time series of images. 
     
     
         20 . The method of  claim 18 , wherein said a map of tissue oxygenation guides localization of said lesions, and said lesions are identified with an overlaid identifier on endoscopic video images.