Abstract:
A percutaneous needle guide includes a housing and an inclinometer secured to the housing for sensing a two dimensional inclination of the housing relative to the earth&#39;s gravitational field and for providing an indication thereof. A percutaneous needle is slidably mounting to the housing in a fixed axial orientation relative to the housing. A needle measuring device is mounted in the housing and operative by linear motion of the percutaneous needle so as to measure the linear position of the percutaneous needle relative to the housing and providing a measurement indication.

Description:
RELATED APPLICATION 
     This application claims priority from U.S. Provisional Application No. 61/774,242, filed 7 Mar. 2013, the subject matter of which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention is directed to a percutaneous needle guide and method for use in image guided procedures. 
     BACKGROUND 
     Cross-sectional imaging for guiding percutaneous procedures in the human body is known. Such procedures use direct visualization to determine a safe needle path that hopefully avoids arteries, veins, nerves, bowel, etc. These known procedures include a planning phase in which scout images are obtained to identify a target such as a lesion. Next, as part of the planning phase, a safe path to the lesion is determined including identification of a skin entrance site. The length of the needle required to reach the target along the selected path is determined. After this planning phase, the procedure is carried out. As part of the procedure, the needle is inserted into the skin at an approximate angle determined during the planning phase but only to a minimal or shallow depth. The patient is then moved into an examination gantry of an imaging device such as CT scanner. While in the scanner, images are obtained that identify the actual position of the needle relative to the target and the planned path. The patient is then pulled out from the scanner and the needle is repositioned and inserted deeper. This process is repeated until the target is reached. 
     SUMMARY OF THE INVENTION 
     In accordance with one example embodiment of the present invention a percutaneous needle guide includes a housing and an inclinometer secured to the housing for sensing a two dimensional inclination of a reference surface of the housing relative to the earth&#39;s gravitational field and for providing an indication thereof. A percutaneous needle is slidably mounted to the housing in a fixed axial orientation relative to the reference surface of the housing. A needle measuring device is mounted in the housing and operative by linear motion of the percutaneous needle to measure the linear position of the percutaneous needle relative to the reference surface of the housing and providing a measurement indication. 
     In accordance with another example embodiment of the present invention, a method is provided for guiding a percutaneous needle comprising the steps of placing the percutaneous needle into a housing, sensing a two dimensional inclination of the housing relative to the earth&#39;s gravitational field and providing an indication thereof, slidably mounting a percutaneous needle to the housing in a fixed axial orientation relative to the housing, and measuring the linear motion of the percutaneous needle relative to the housing and providing a measurement indication. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which: 
         FIG. 1  is a top view of a percutaneous needle guide made in accordance with an example embodiment of the present invention; 
         FIG. 2  is a side elevational cross-sectional view of the percutaneous needle guide of  FIG. 1 ; 
         FIG. 3  is an illustration of the percutaneous needle guide of  FIG. 1  operatively placed on a patient viewing the patient in cross-section; 
         FIG. 4  is a top view of a percutaneous needle guide made in accordance with another example embodiment of the present invention; and 
         FIG. 5  is a side elevational cross-sectional view of the percutaneous needle guide of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , a percutaneous needle guide  10 , made in accordance with an example embodiment of the present invention, is shown. The guide  10  includes a housing  12  having an inclinometer  14 , a linear needle measuring device  16 , and an adjustable needle holding device  18 . A percutaneous needle  20  is slidably received in the adjustable needle holding device  18  and is operatively coupled to the linear needle measuring device  16 . The adjustable needle holding device  18  is adapted to slidably hold any of a plurality of different diameter percutaneous needles along a Z-axis that is perpendicular to a bottom wall  22  of the housing  12 . The bottom wall  22  of the housing  12  is used as a reference surface for further measurements. 
     The inclinometer  14 , which may also be referred to as a clinometer or a level sensor, can take any of several known forms. The inclinometer  14  measures the inclination of the housing  12  relative to the earth&#39;s gravitational field, and specifically, the position of the reference surface  22  relative to the earth&#39;s gravitational field. 
     In accordance with one example embodiment of the present invention, the inclinometer  14  could include a vessel  30  mounted in a top wall  31  of the housing  12 . The surface of the top wall  31  is parallel to the bottom wall  22 . Those skilled in the art will appreciate, that for the purposes of the inclinometer  14 , the surface of the top wall  31  is, in effect, also a reference surface. 
     The vessel  30  is, in accordance with one example embodiment of the present invention, generally circular shape, and includes a liquid  32  and a float  34 . The float  34  includes a centrally positioned indicator portion  36  that extends upward from the float. When the housing  12  has its bottom reference wall  22  perpendicular to the earth&#39;s gravitational field, the indicator portion  36  is centered at the top of the vessel  30 . This is referred to as the zero angle position, i.e., no inclination of the housing  12 . 
     The vessel  30  includes angle indication markings  44  along an X-axis direction and a Y-axis direction so that the position of the indicator portion  36  relative to the markings  44  will provide an indication of the angle of inclination of the housing  12  relative to the earth&#39;s gravitational field. Values along the X-axis represent pitch and values along the Y-axis represents roll of the housing  12  relative to the earth&#39;s gravitational field. 
     The device  18  includes an adjustable screw  50  threaded into the housing  12  and into a needle receiving passage  52  of the housing  12 . A V-shaped needle holder  54  is slidably mounted in the passage  52  and receives the needle  20  positioned in the passage  52  and slidably holds the needle  20  so that its axis is parallel with the Z-axis of the housing  12 . A linear measuring device  16  includes a first wheel  60  mounted for rotation about an axis  62  via an axle  63 . The first wheel  60  is positioned to contact the needle  20  when the screw  50  is turned so as to snug the V-shaped needle holder  54  against the needle  20 . The V-shaped holder  54  has a bearing surface that allows the needle  20  to slide along the Z-axis. 
     When the needle  20  is slid in the housing in a Z-axis direction, the linear movement of the needle  20  causes the first wheel  60  to rotate about the axis  62 . A measurement tape  64  wraps around the first wheel  60  and a second wheel  66  mounted for rotation about an axis  67  on an axle  68  mounted substantially in parallel to the axis  62 . A measurement viewing window  70  is located in the housing  12  above the measuring tape  64  that allows the user to view a linear position measurement of the needle  20 . The position indication provided by the measurement tape can be calibrated so that a zero position indication can be provided through the window  70  when the needle tip  72  is positioned even with the bottom wall  22  of the housing. This is accomplished by sliding the needle  20  until a zero measurement is indicated in the window  70 , loosening the adjustment screw  50  until the needle  20  no longer contacts the measurement tape, slide the needle until the tip  72  is flush with the bottom wall surface  22 , then re-tightening the adjustment screw. The length of tape needed and the number of internal wheels need can be adjusted so as to permit sufficient linear measurement of needle movement to a selected Z-axis depth. 
     Referring to  FIGS. 4 and 5 , another example embodiment of a measuring device is illustrated including a single measurement wheel  80  operatively contacting the needle  20  and mounted for rotation about an axis  81 . The single wheel  80  includes measurement indications  82 . The wheel is mounted below a clear measurement window  84  for providing a measurement indication of linear needle position along the Z-axis. The combination of the measurement wheel  80  and needle  20  can be calibrated in a similar manner as with the measurement tape. 
     Also, the vessel  30  could be filled with a supermajority of liquid except for a relatively small area of gas that forms a bubble  90  that would float and provide an indication of the inclination of the housing  12 . Furthermore, the vessel  30  could be mounted in the housing  12  so that it could rotate about the Z-axis of the housing  12  so that the angle indications could be rotated to any desired angle relative to an X and Y axis of the housing itself. Such an arrangement provides a different zero position option and angle reading option. 
     Referring to  FIG. 3 , an example use of the percutaneous needle guide  10  of the present invention on a patient  100  (shown in cross-section) is illustrated. Assume that the patient  100  has a lesion  106  and nearby blood vessels  108 . Further, assume that it is desired to biopsy the lesion using a percutaneous needle. It is desirable to have the needle enter the lesion  106  and not hit the blood vessels  108 . The patient  100  is first placed into an imaging gantry such as a CT scanner. Images are obtained to identify the actual position of the lesion and blood vessels. The X, Y angle θ is determined and the Z axis depth is determined along a best path scenario to hit the target. The guide  10  is positioned onto the patient at the determined X, Y angle and the needle inserted to the determined depth along the Z axis using the guide measuring device. The inclination reading of the guide  10  and the Z axis depth measurement are visible to the doctor so that the needle insertion could occur while the patient is in the gantry. Also, the variable needle holding arrangement permits all needle sizes needed. 
     Referring to  FIG. 2 , adhesive mounting devices  110  could be attached to the bottom wall  22  of the housing  12  to aid in securing the housing  12  to the patient  100  during any procedure. In accordance with one embodiment, the adhesive feet  110  could be malleable flaps or other means for allowing the device  10  to adhere to the skin surface of the patient without requiring the device  10  to rest flush with the skin surface. 
     In accordance with one example embodiment, the guide  10  is made of plastic with liquid in the inclinometer  14 . If the guide  10  is to be used with imaging devices other than CT scanners or MRI scanners, then the guide  10  could be made with metal parts. For example, if the guide were to be used in a biopsy procedure using ultrasound guidance, the guide could have metal parts. Also, under such uses, the inclinometer could be an electronic inclinometer instead of the float arrangement described. Also, an electronic needle displacement measuring device could also be used in situations where metal is not a concern. Using an electronic inclinometer and an electronic needle displacement measuring device permits use of a computer for monitoring and feedback of the sensor signals. 
     From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. For example, the adjustable needle holding device  18  could be a different type of slidable securing means such as a tape, string, or plastic strap that fits into a groove in the housing  12  between the needle and the housing. Once the needle is placed into the needle receiving passage  52 , the plastic strap is fed through the groove to take up the space between the needle and the housing or the “V” shaped member to hold the needle in operative contact with the measuring tape or wheel. Also, rather than an inclinometer that uses fluid floats or bubbles, a weighted needle arrangement could be used with one needle for the X-axis and one needle for the Y-axis. Each X, Y needle would pivot about its associated mounting axle with the weighted end below the pivot point. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.