Dynamic planning method for needle insertion

Abstract

A method of planning an image-guided interventional procedure to be performed on a patient, where expected motion of the patient, such as that of a breathing cycle, is determined on a sequence of preoperative images, and the procedure trajectory is planned accordingly. The method takes into account the initial positions of the interventional entry, the target region, and any obstructions or forbidden regions between the entry point and the target region, and uses object tracking methods of image processing on the preoperative images to determine how the positions of these three elements change relative to each other during the patient's motion cycle. The method may automatically search in at least some of the preoperative images taken at different temporal points of the motion cycle, for a path connecting the entry point with the target and avoiding the obstacles, which provides minimal lateral pressure on the patient's tissues.

1 . A method of pre-operatively planning an image-guided insertion procedure for inserting a tool into a region of interest of a subject, comprising:
 (a) obtaining a plurality of images of the region of interest, the plurality of images derived at different times during breathing cycle of the subject;   (b) calculating a trajectory for said insertion procedure between an entry point for the tool and a target point, which avoids entry into any of one or more forbidden regions, wherein said entry point, said target point and said one or more forbidden regions have been defined on a first image of the plurality of time-separated images of the region of interest;   (c) determining changes in the position of said entry point, target point and any of the one or more forbidden regions into which entry by said tool is forbidden in a different image of said plurality of images generated at a time different from that at which said first image of said plurality of images was generated, and   (d) repeating step (b) on said different image of said plurality of images based on the changes in position determined in step (c).   
     
     
         2 . The method according to  claim 1 , further comprising the step of:
 (e) checking for each of said trajectory, one or more trajectory characteristics selected from:   (i) the curvature, (ii) the entry angle at each of said entry point, and (iii) the proximity to any of said one or more forbidden regions, to determine if one or more predetermined levels relating to said one or more trajectory characteristics is exceeded, and   (f) if said one or more predetermined levels relating to said trajectory characteristics are determined not to be exceeded in each of said trajectory, ascertaining pre-operatively that said trajectory are suitable trajectories for said insertion procedure.   
     
     
         3 . The method according to  claim 2 , wherein if at least one of said one or more predetermined levels relating to said trajectory characteristics is determined to be exceeded, the method further comprises the steps of:
 (g) defining an alternative entry point on said different image, and repeating steps (b) to (f) using said changed entry point with said target point and said one or more forbidden regions initially defined in step (c).   
     
     
         4 . The method according to  claim 1 , further comprising the step of storing said entry point, said target point and said one or more regions into which entry by said insertion procedure is forbidden. 
     
     
         5 . The method according to  claim 1 , wherein determining the positions of said entry point, said target point and said one or more forbidden regions in said one or more other images in step (b) is performed using one or more object tracking image processing methods. 
     
     
         6 . The method according to  claim 1 , wherein the one or more forbidden region includes at least one of: a bone, a blood vessel, a nerve, an internal organ and an implanted medical element. 
     
     
         7 . The method according to  claim 1 , wherein said tool is any one of: a needle, a port, an introducer, an ablation catheter, a surgical tool or a fluid delivery tool. 
     
     
         8 . The method according to  claim 2 , further comprising selecting an optimal trajectory for said insertion procedure from the suitable trajectories. 
     
     
         9 . The method according to  claim 8 , wherein selecting which of said suitable trajectories is the optimal trajectory comprises determining which of said suitable trajectories comprises one or more of: the least curvature, the least distance between said tissue entry point and said target point and the greatest distance from one or more of said one or more forbidden regions. 
     
     
         10 . A system for pre-operatively planning an image-guided insertion procedure for inserting a tool into a region of interest of a subject, comprising
 a display configured to display a plurality of images of a region of interest derived at different times during the breathing cycle of the subject;   a user interface configured to receive user inputs; and   at least one processor configured to:
 calculate a trajectory for said insertion procedure between an entry point for the tool and a target point, which avoids entry into any of one or more forbidden regions, wherein said entry point, said target point and said one or more forbidden regions have been defined on a first image of the plurality of time-separated images of the region of interest; 
 determine changes in the position of said entry point, target point and any of the one or more forbidden regions into which entry by said tool is forbidden in a different image of said plurality of images generated at a time different from that at which said first image of said plurality of images was generated, and 
 repeat the calculating on said different image of said plurality of images based on the determined changes in position determined. 
   
     
     
         11 . The system according to  claim 10 , wherein the processor is further configured to check, for each of said trajectory, one or more trajectory characteristics selected from: (i) the curvature, (ii) the entry angle at each of said entry point, and (iii) the proximity to any of said one or more forbidden regions, to determine if one or more predetermined levels relating to said one or more trajectory characteristics is exceeded, and if said one or more predetermined levels relating to said trajectory characteristics are determined not to be exceeded in each of said trajectory, ascertaine pre-operatively that said trajectory are suitable trajectories for said insertion procedure. 
     
     
         12 . The system according to  claim 11 , wherein the processor is further configured to select an optimal trajectory for said insertion procedure from the suitable trajectories. 
     
     
         13 . The system according to  claim 10 , wherein the user inputs comprise marking of positions of the entry point, the target and the one or more forbidden areas on the first image. 
     
     
         14 . The system according to  claim 10 , further comprising a memory component configured to store at least the plurality of images, the entry point, the target and the one or more forbidden areas. 
     
     
         15 . The system according to  claim 10 , further comprising a communication module configured to obtain the plurality of images from an imaging system. 
     
     
         16 . The system according to  claim 10 , wherein the processor is further configured to define at least one of the entry point, the target and the one or more forbidden areas, on the first image. 
     
     
         17 . The system according to  claim 10 , wherein said tool is any one of: a needle, a port, an introducer, an ablation catheter, a surgical tool or a fluid delivery tool.