Automatic contrast-agent injection detection

Abstract

Apparatus and methods are described, for use with a contrast agent that is injected into a blood vessel of a subject. The apparatus and methods include acquiring a plurality of image frames of the subject's blood vessel, acquisition of the image frames commencing prior to injection of the contrast agent into the blood vessel. Using at least one processor, one of the image frames is automatically identified as being an image frame in which an angiographic sequence commenced, by determining that, in the image frame, there is a change in a characteristic of the image frame relative to at least one image frame acquired prior to the image frame that is indicative of a presence of contrast agent within the image. An output is generated at least partially in response thereto. Other applications are also described.

1 - 68 . (canceled) 
     
     
         69 . A method for use with a contrast agent that is injected into a blood vessel of a subject, comprising:
 acquiring a plurality of image frames of the subject's blood vessel, acquisition of the image frames commencing prior to injection of the contrast agent into the blood vessel;   using at least one processor, automatically identifying one of the image frames as being an image frame in which an angiographic sequence commenced within the acquired image frames, by determining that, in the image frame, there is a change in a characteristic of the image frame relative to at least one image frame acquired prior to the image frame that is indicative of a presence of contrast agent within the image; and   using the at least one processor, generating an output at least partially in response to identifying the image frame in which the angiographic sequence commenced.   
     
     
         70 . The method according to  claim 69 , wherein the method is for use with contrast agent that is injected into the blood vessel via a distal end of a catheter, and wherein determining that, in the image frame, there is a change in a characteristic of the image frame relative to at least one image frame acquired prior to the image frame comprises determining that, in the image frame in a vicinity of the distal end of the catheter within the image frame, there is a change in the characteristic of the image frame relative to at least one image frame acquired prior to the image frame. 
     
     
         71 . The method according to  claim 69 , wherein determining that, in the image frame, there is a change in a characteristic of the image frame relative to at least one image frame acquired prior to the image frame comprises determining that, in the image frame, there is a change in a color of a substantial number of pixels, relative to the at least one image frame acquired prior to the image frame. 
     
     
         72 . The method according to  claim 69 , wherein determining that, in the image frame, there is a change in a characteristic of the image frame relative to at least one image frame acquired prior to the image frame comprises determining that, in the image frame, there is a change in a grayscale level of a substantial number of pixels, relative to the at least one image frame acquired prior to the image frame. 
     
     
         73 . The method according to  claim 69 , wherein generating the output at least partially in response to identifying the image frame in which the angiographic sequence commenced comprises deriving a roadmap of the blood vessel using an image frame belonging to the angiographic sequence. 
     
     
         74 . Apparatus for use with a contrast agent that is injected into a blood vessel of a subject, comprising:
 an imaging device configured to acquire a plurality of image frames of the subject's blood vessel, acquisition of the image frames commencing prior to injection of the contrast agent into the blood vessel; and   at least one processor configured to:
 automatically identify one of the image frames as being an image frame in which an angiographic sequence commenced within the acquired image frames, by determining that, in the image frame, there is a change in a characteristic of the image frame relative to at least one image frame acquired prior to the image frame that is indicative of a presence of contrast agent within the image; and 
 generate an output at least partially in response to identifying the image frame in which the angiographic sequence commenced. 
   
     
     
         75 . The apparatus according to  claim 74 , wherein the apparatus is for use with contrast agent that is injected into the blood vessel via a distal end of a catheter, and wherein the processor is configured to determine that, in the image frame, there is a change in a characteristic of the image frame relative to at least one image frame acquired prior to the image frame by determining that, in a vicinity of the distal end of the catheter within the image frame, there is a change in the characteristic of the image frame relative to at least one image frame acquired prior to the image frame. 
     
     
         76 . The apparatus according to  claim 74 , wherein the processor is configured to determine that, in the image frame, there is a change in a characteristic of the image frame relative to at least one image frame acquired prior to the image frame that is indicative of a presence of contrast agent within the image, by determining that, in the image frame, there is a change in a color of a substantial number of pixels, relative to the at least one image frame acquired prior to the image frame. 
     
     
         77 . The apparatus according to  claim 74 , wherein the processor is configured to determine that, in the image frame, there is a change in a characteristic of the image frame relative to at least one image frame acquired prior to the image frame that is indicative of a presence of contrast agent within the image, by determining that, in the image frame, there is a change in a grayscale level of a substantial number of pixels, relative to the at least one image frame acquired prior to the image frame. 
     
     
         78 . The apparatus according to  claim 74 , wherein the processor is configured to generate the output at least partially in response to identifying the image frame in which the angiographic sequence commenced by deriving a roadmap of the blood vessel using an image frame belonging to the angiographic sequence.