Abstract:
A coiling parameterization tool includes a processor and a display for displaying values of lumen volume, packing and coiling parameters for filling a lumen in relation to a desired packing. The processor is configured to detect a change in one of the displayed values and, in response to the change, to automatically evaluate, change and display remaining values displayed on the display.

Description:
FIELD OF THE INVENTION 
     The invention relates to determining coiling parameters for filling a lumen with at least one coil. 
     BACKGROUND OF THE INVENTION 
     Michel Piotin et al., Intracranial Aneurysms: Treatment with Bare Platinum Coils—Aneurysm Packing, Complex Coils, and Angiographic Recurrence, Radiology: Volume 243: Number 2—May 2007, pp. 500-508 describe an assessment, with three-dimensional rotational angiography, of the relationship between packing, helical and complex coils, and angiographic recurrence of aneurysms treated with coils. Such treatments are performed by endovascular deployment of one or several coils in an aneurysm. 
     An aneurysm is one example for a lumen to be filled with coils. 
     In the article by M. Piotin et al., packing is defined as the ratio of coil volume to aneurysm volume. 
     SUMMARY OF THE INVENTION 
     In the article by M. Piotin et al. the aneurysms which were treated were small, with a mean aneurysm volume of 152 mm 3 . For such aneurysms it was found that packing does not play an important role in the recurrence rate, whereas previous studies indicated that packing of more than 20% to 25% was found to protect against recurrence. For treatment of said small aneurysms packing of 27% for complex coils and 26% for helical coils was employed. The choice of the type (helical or complex) and brand of coil used was up to the physician performing the treatment procedure. 
     An object of the invention is providing a tool for easily and appropriately determining coiling parameters for filling a lumen with at least one coil. 
     The invention provides a method including the steps of determining the volume of a lumen to be filled by at least one coil, and interactively determining at least one coil parameter in relation to the required packing. The interactive determination of coiling parameters provides a wide choice of selections for a practitioner using the method according to the invention, prior to or during deployment of coils. 
     The volume of the lumen may be preset, or may be obtained based on three-dimensional rotational angiography, as suggested by J. Bruijns, Fully-Automatic Labelling of Aneurysm Voxels for Volume Estimation, Procs BVM, 2003, pp. 51-55. 
     According to an embodiment of the invention, the at least one coil parameter is a number of coils, a coil thickness, or a coil length. The packing may be predetermined, and the number of coils may be determined based on the packing and at least one further coil parameter. Alternatively, the number of coils based on at least one further coil parameter may be predetermined, and the packing may be determined based thereon. 
     According to an embodiment of the method of the invention, the at least one coil parameter includes a first coil parameter set and at least a second coil parameter set. Each one of these coil parameter sets relates to a certain type of coil. A first number of coils of a first type based on the first coil parameter set may be determined, and a second number of coils of a second type based on the second coil parameter set may be determined. Therefore, for interactively determining coiling parameters different coil types might be used for filling the same lumen, in consideration of a desired packing, of a particular shape of the lumen, and so on. Of course, the number of types of coils is not limited to two, such that, for example, also three or more different types of coils might be used. 
     According to another embodiment of the inventive method, the values of the entities (or at least some entities) used in the method are displayed on the screen of a display device. This allows an easy interaction with and information of an operator. 
     The invention also relates to a device with an input unit configured to enter at least one selected entity used in the method, a processor configured to interactively determine said at least one coil parameter, and an output unit configured to output at least one selected entity used in the method. Such a device enables an easy interaction with an operator who, after having entered a selected entity (for example coil parameter), will be immediately informed of a corresponding output. 
     The invention also provides a computer program product enabling a processor to carry out the method according to the invention or any embodiment thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1(A) to 1(D)  show screenshots of a screen of a display unit (output unit) with entities or parameters entered by a user or provided by a device according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The invention will be described in more detail hereinafter based on preferred or advantageous embodiments thereof. 
     The following terms and definitions will be used. 
     aneurysm volume AV in ml (1 ml=1000 mm 3 ) 
     coil thickness WD: thickness (in inches, 1 in=25.4 mm); i. e. thickness of the coil wire 
     coil length WL: length (in mm) of the coil wire 
     coil volume VC=(π/4)×WD 2 ×WL (in case of a cylindrical coil wire with a thickness WD) 
     packing=VC/AV (dimensionless parameter) 
     number of coils=(packing) AV/VC 
     The following procedure explains the method of the invention. Indicated in (row/column) below are user input (in bold) and system response (in italics). Such matrizes may be presented as screenshots, for example. Step 1 starts with an aneurysm volume AV of 0.168 ml, a packing of 80%, a single type (1) of a coil, a coil thickness of 0.016 inches, and a coil length WL of 200 mm. This results in that a number of 5.2 such coils are required. 
     Since the coil volume VC is determined based on the volume of the coil wire, i.e. on the volume of the material of the coil the value of VC is independent of the particular shape of the coil. 
     In more detail, indicated hereinafter in (row/column) are: 
     (1,1) aneurysm volume AV in ml 
     (1,2) packing in % 
     (1,3) number of coil types 
     (2,1) coil thickness WD in inches 
     (2,2) coil length WL in mm 
     (2,3) number of coils (of the type in row 3) 
     Step 1 At start-up this dialog comes up 
                                         0.168   80   1       0.016   200   5.2                    
Step 2 Changing the number of different coils (1→2) adds the third row
 
                                         0.168   80   2       0.016   200   5.2       0.014   100   0                    
Step 3 Changing the number of coils to 3 changes the packing density to 46
 
                                         0.168   46   2       0.016   200   3       0.014   100   0                    
Step 4 Changing the packing modifies the number of coils of the last row
 
                                         0.168   80   2       0.016   200   3       0.014   100   5.7                    
Step 5 Changing the coil thickness changes the packing
 
                                         0.168   71   2       0.016   200   3       0.012   100   5.7                    
Step 6 Changing the packing modifies the number of coils of the last row
 
     
       
         
               
               
               
             
           
               
                   
               
             
             
               
                 0.168 
                 80 
                 2 
               
               
                 0.016 
                 200 
                 3 
               
               
                 0.012 
                 200 
                 7.8 
               
               
                   
               
             
          
         
       
     
     This can be repeated with additional rows. In general, modifying coil parameters or aneurysm volume will change packing. Changing packing will change number of coils in the last row. 
     There are a few configurable defaults as follows: 
     1) The metrics 
     2) Size and length of the coils; 
     Coils are added automatically with size 0 and thickness, length as shown below. 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 0.016 
                 200 
               
               
                   
                 0.014 
                 100 
               
               
                   
                 0.012 
                 100 
               
               
                   
                 0.010 
                 100 
               
               
                   
                   
               
             
          
         
       
     
     The selection is based on the last coil thickness. 
     
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 0.168 
                 80 
                 4 
                 Changing number of different coils to 4 at state 4 
               
               
                 0.016 
                 200 
                 3 
                 will add sizes 0.012 and 0.010 (i.e. thickness) 
               
               
                 0.014 
                 100 
                 5.7 
               
               
                 0.012 
                 100 
                 0 
               
               
                 0.010 
                 100 
                 0 
               
               
                 0.168 
                 80 
                 3 
                 Changing number of different coils to 3 at state 6 
               
               
                 0.016 
                 200 
                 3 
                 will add size 0.010 
               
               
                 0.012 
                 100 
                 7.8 
               
               
                 0.010 
                 100 
                 0 
               
               
                   
               
             
          
         
       
     
       FIGS. 1(A) to 1(C)  show screens (screenshots) of a display device (output unit) of a device according to the invention, in various stages of the method according to the invention. 
     In  FIG. 1(A)  the number of coils is 11.4, for the coil parameters indicated in the figure and a packing of 80%. If the packing is changed to 77%, the number of coils is 11 as shown in  FIG. 1(B) . 
       FIG. 1(C)  shows a case where three (Nr. coils) different coils are used, with coil parameters indicated in rows 2 to 4 in the figure, and a packing of 80%. If then the packing is reduced to 70% as shown in  FIG. 1(D) , the negative number −7.7 for the number of coils indicates that 7.7 coils of the third coil type in the fourth row will have to be removed. 
     In summary, the invention provides an easy to use coiling parameterization tool that allows a user to interactively evaluate coiling parameters for filling a lumen in relation to a desired packing and the automatically determined or manually indicated volume of the lumen. 
     The lumen may be an aneurysm to be filled with at least one coil through a medical intervention, for providing an embolization. 
     Other fields of filling a lumen with coils are vessels to be filled with coils which act as a catalyst or contain a catalyst. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. 
     For example, it is possible to operate the invention in an embodiment wherein certain entities do not have to be entered by a user, but are presented as a list of default values for selection by the user, e.g. a list of coil parameters of coils which are commercially available and/or comply with regulations (in particular in the medical field). 
     Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solidstate medium supplied together with or as part of other hardware, but may also be distributed I other forms, such as via the Internet or other wired or wireless telecommunication systems.