US20080146939A1 - Apparatus and method for image guided insertion and removal of a cannula or needle - Google Patents

Abstract

A means for holding a selected cannula such that the cannula is controllably restricted in motion in all but one line, but still able to slide along the line relatively freely. The motion restricting force may be selectively varied, thereby allowing an unrestricted separation of the cannula and the holding/guide device.

Description

FIELD OF THE INVENTION
• This invention relates to a magnetic system for manipulating the placement of a needle or cannula in a biologic subject.
BACKGROUND OF THE INVENTION
• The following applications are incorporated by reference as if fully set forth herein: U.S. application Ser. Nos. 11/258,592 filed Oct. 24, 2005 and 11/874,824 filed Oct. 18, 2007.
• Unsuccessful insertion and/or removal of a cannula, a needle, or other similar devices into vascular tissue may cause vascular wall damage that may lead to serious complications or even death. Image guided placement of a cannula or needle into the vascular tissue reduces the risk of injury and increases the confidence of healthcare providers in using the foregoing devices. Current image guided placement methods generally use a guidance system having a mechanical means for holding specific cannula or needle sizes. The motion and force required to disengage the cannula from the guidance system may, however, contribute to a vessel wall injury, which may result in extravasation. Complications arising from extravasation resulting in morbidity are well documented. Therefore, there is a need for image guided placement of a cannula or needle into vascular tissue while still allowing a health care practitioner to use standard “free” insertion procedures that do not require a guidance system to hold the cannula or needle.
SUMMARY OF THE INVENTION
• This invention relates to a magnetic system for manipulating the placement of a needle or cannula for the purposes of positioning via image devices into an artery, vein, or other body cavity and releasing the cannula once the placement is successfully completed.
• The invention provides a means for holding a selected cannula such that the cannula is controllably restricted in motion in all but one line, but still able to slide along that line relatively freely. The motion restricting force may be selectively varied, thereby allowing an unrestricted separation of the cannula and the holding/guide device.
BRIEF DESCRIPTION OF THE DRAWINGS
• Embodiments of the present invention are described in detail below with reference to the following drawings.
• FIG. 1 is a cross-sectional view of a first embodiment;
• FIG. 1B is an alternate embodiment of the first embodiment;
• FIG. 1C is a plan view of the first embodiment;
• FIG. 1D is a plan view of another embodiment;
• FIG. 1E is a plan view of yet another embodiment;
• FIG. 2A is a cross-sectional view of a second embodiment;
• FIG. 2B is a plan view of the second embodiment;
• FIG. 3A is a cross-sectional view of an alternate embodiment of the second embodiment;
• FIG. 3B is a plan view of the alternate embodiment of the second embodiment;
• FIG. 4A is a third embodiment of the invention;
• FIG. 4B is a plan view of the third embodiment;
• FIG. 5A is an embodiment of a magnetic strip;
• FIG. 5B is an alternate embodiment of the magnetic strip;
• FIG. 6A is an embodiment of a magnetic guide assembly having the embodiments ofFIG. 5A;
• FIG. 6B is an alternate embodiment of a magnetic guide assembly having the magnetic strip embodiments ofFIG. 5B;
• FIG. 7A schematically depicts removing a strip from the device depicted inFIG. 6A;
• FIG. 7B is a progression of the strip removal ofFIG. 7A;
• FIG. 7C is a continuation of strip removal ofFIG. 7B;
• FIG. 7D is near complete removal of the strips from the magnetic guidance device;
• FIG. 7E is an alternate arrangement of the magnetic strips to the magnetic guidance device;
• FIG. 8A is a cross-section of a fifth embodiment in the form of a magnet-ferrite core assembly;
• FIG. 8B depicts the assembly ofFIG. 8A in cross-section holding a cannula in a gap;
• FIG. 8C depicts the assembly ofFIG. 8A in cross-section where removal of the magnet causes release of the cannula;
• FIG. 9A is an alternate embodiment of the magnet-ferrite core assembly ofFIG. 8A;
• FIG. 9B depicts the alternate embodiment ofFIG. 9A magnetically holding a cannula;
• FIG. 9C schematically shows in cross-section the release of the cannula from the assembly ofFIG. 9A.
• FIG. 9D shows the complete release of the cannula from the assembly ofFIG. 9A;
• FIG. 10A is an isometric view of the magnetic core assembly ofFIG. 8A;
• FIG. 10B is a schematic isometric depiction of the operation of the magnet core assembly ofFIG. 8A;
• FIG. 10C is a schematic depiction of the operation of the magnet core assembly ofFIG. 8A;
• FIG. 11A is an alternate embodiment of an isometric view of the alternate embodiment depicted inFIG. 9A;
• FIG. 11B depicts an operation of the embodiment shown inFIG. 11A;
• FIG. 12A is an alternate embodiment of a pair of magnet core assemblies ofFIG. 8A;
• FIG. 12B is an isometric view of a schematic operation of an embodiment ofFIG. 12A;
• FIG. 13A is an isometric view schematically depicting an electro magnetic embodiment ofFIG. 12A;
• FIG. 13B is an isometric view schematically depicting the electromagnet ofFIG. 13A;
• FIG. 14 illustrates in a partial isometric and side view of a V-Block configured needle guidance device mounted to an ultrasound transceiver;
• FIG. 15 illustrates in a partial isometric and side view of a magnet-ferrite core configured needle guidance device mounted to an ultrasound transceiver;
• FIG. 16 is an alternate embodiment ofFIG. 8A for detachably attaching a magnet-ferrite needle guidance to an ultrasound transducer housing;
• FIG. 17 is an alternate embodiment ofFIG. 12A mounted to a transducer housing;
• FIG. 18A is a side view of an ultrasound scanner having a magnetic guide assembly;
• FIG. 18B is an isometric view and exploded view of components of the device ofFIG. 18A;
• FIG. 19A is a side view of alternate embodiment ofFIG. 18A utilizing a rotating magnet;
• FIG. 19B is an isometric view and exploded view of components of the device ofFIG. 19A;
• FIG. 20A is a side view of alternate embodiment ofFIG. 19A utilizing a pulling magnet; and
• FIG. 20B is an isometric view and exploded view of components of the device ofFIG. 20A.
• FIGS. 1 and 2 are diagrams showing one embodiment of the present invention;
• FIG. 3 is a diagram showing additional detail for a needle shaft to be used with one embodiment of the invention;
• FIGS. 4A and 4B are diagrams showing close-up views of surface features of the needle shaft shown inFIG. 3;
• FIG. 5 is a diagram showing imaging components for use with the needle shaft shown inFIG. 3;
• FIG. 6 is a diagram showing a representation of an image produced by the imaging components shown inFIG. 5;
• FIG. 7 is a system diagram of an embodiment of the present invention;
• FIG. 8 is a system diagram of an example embodiment showing additional detail for one of the components shown inFIG. 2;
• FIGS. 9-10 are flowcharts of a method of displaying the trajectory of a cannula in accordance with an embodiment of the present invention; and
• FIG. 11 schematically depicts an alternative embodiment of a needle having a distribution of reflectors located near a bevel of the needle.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• The present invention relates to an apparatus and a method for image guided insertion and removal of a cannula or needle. Many specific details of certain embodiments of the invention are set forth in the following description and inFIGS. 1 through 20B to provide a thorough understanding of such embodiments. One skilled in the art, however, will understand that the present invention may have additional embodiments, or that the present invention may be practiced without several of the details described in the following description.
• FIG. 1A is a schematic cross-section view of a needle/cannula guide device10 according to an embodiment of the invention. The needle/cannula guide device10 includes a V-block12 that supports a needle orcannula18. The V-block12 includes two opposing sections that are coupled to each other at an apex.Magnetic strips16 are positioned on an exterior portion of the V-block12 that magnetically retain thecannula18 within the V-block12. Accordingly, the V-block12 may be fabricated from a suitably non-magnetic material, so that magnetic fields generated by the magnet strips16 retain themetal needle18 in the V-block12. The non-magnetic material of the V-block12 may be comprised of a low friction polymeric material such as, for example, Teflon®, Nylon®, or Delrin®. Alternatively, it may be comprised of a ferromagnetic material that may similarly convey the magnetic fields generated by themagnets16. Themagnets16 may be fixedly coupled to the V-block12. Alternately, themagnets16 may be removably coupled to the V-block12.
• FIG. 1B is a schematic cross-section view of a needle/cannula guide device10A according to another embodiment of the invention. Many of the details of the present embodiment have been described in detail in connection with the embodiment shown inFIG. 1A, and in the interest of brevity, will not be described further. Theguide device10A includes afoil wrapper20 or other suitable wrapper materials that substantially encloses thecannula18. Thewrapper20 may be subjected to sterilization procedures so that theassembly10A may be sterilized by autoclaving, irradiation, or other known chemical processes. Thefoil wrapper20 is generally sealably coupled to the V-block12 so that thecannula18 is substantially isolated from contaminants, yet is configured to be easily removed from the V-block12.
• FIGS. 1C, D, and E illustrate alternate embodiments of thecannula guide devices10 and10A, as shown inFIG. 1A andFIG. 1B, respectively.
• FIG. 1C is a plan view of thedevices10 and10A where thecannula18 is positioned in the V-block12 and is held in position by themagnets16, which extend uninterrupted along a length of the V-block12.FIG. 1D is a plan view of thedevices10 and10A that shows a first set ofmagnets16A positioned on first selected portions of the V-block12, and a second set ofmagnets16B that are positioned on second selected portions of the V-block12. As shown inFIG. 1D, thesecond set16B may be positioned between thefirst set16A.FIG. 1E is a plan view of thedevices10 and10A that showsmagnets16A interruptably positioned on the V-block12. Although themagnets16,16A and16B are generally depicted inFIG. 1C,FIG. 1D ANDFIG. 1E as rectangular, it is understood that themagnets16,16A and16B may have any regular shape.
• FIGS. 2A and 2B are cross sectional and plan views, respectively, of acannula guide device20A according to another embodiment of the invention. InFIG. 2A, the V-block12 includes four magnet strips24, positioned on each arm of the V-block12 that are used to generate a retaining force on theneedle18. Referring now also toFIG. 2B, the placement of themagnets24 on the V-block12 advantageously permit the V-block12 to accommodate a variety of needle diameters.
• FIGS. 3A and 3B are cross sectional and plan views, respectively, of acannula guide device20B according to still another embodiment of the invention. Thedevice20B includesmagnets24B that are operable to generate an attractive force that is different frommagnets24A. Accordingly, themagnets24B may generate a greater attractive force on theneedle18 than themagnets24A. Alternately, themagnets24A may generate a greater attractive than themagnets24B.
• FIGS. 4A and 4B are cross sectional and plan views, respectively, of acannula guide device20C according to still yet another embodiment of the invention. Thedevice20C includes a unitary magnet strips27 having regions that generate different attractive forces on theneedle18. Accordingly, the unitarymagnetic strips27 include a firstmagnetic strip portion26A and a secondmagnetic strip portion26B. The attractive force generated by theportion26A may be greater than the attractive force generated by theportion26B, or the attractive force generated by theportion26B may be greater than the attractive force generated by theportion26A.
• FIGS. 5A and 5B are isometric views, respectively, ofmagnetic strips30A and30B that may be removably coupled to the V-block12 (FIG. 1A). Themagnetic strips30A and30B include atab34 configured to apply a pulling force to thestrips30A and30B. Referring now in particular toFIG. 5A, a unitarymagnetic element32 is positioned on thestrip30A that generates a relatively uniform attractive force on the needle18 (not shown).Magnetic strip30B shown inFIG. 5B includes amagnetic element36 that also includesmagnetic portions36A and36B that are configured to generate different attractive forces on the needle18 (not shown). Themagnetic strips30A and30B may also include an adhesive material that is operable to retain thestrips30A and30B onto external surfaces of the V-block12.
• FIGS. 6A and 6B are respective isometric views ofneedle guidance devices40A and40B. InFIG. 6A, theneedle guidance device40A includes themagnetic strips30A as shown inFIG. 5A that are positioned on the exterior of the V-block12. The attractive force of themagnetic strips30A magnetically holds theneedle18 within an inner portion of the V-block12. InFIG. 6B, theneedle guidance device40B includes themagnetic strip30B ofFIG. 5B positioned on the V-block12.
• FIGS. 7A-7E are isometric views of theneedle guidance device40A that will be used to a method of using theneedle guidance device40A according to another embodiment of the invention.FIG. 7A andFIG. 7B show a first selected one of themagnetic strips30A being progressively removed from the V-block12. The first selected one of thestrips30A may be removed by a user by grasping thetab34 and applying a pulling force on thetab34 in the direction shown. Accordingly, the attractive force on theneedle18 is also progressively reduced. A selected length of thestrip30A may be removed so that a desired attractive force acting on theneedle18 is attained. Referring now toFIG. 7C, a second selected one of thestrips30A may be removed by grasping thetab34 and applying a pulling force on thetab34 in a suitable direction. As a result, the attractive force on theneedle18 is still further reduced. AlthoughFIGS. 7A through 7C show a single magnetic strip applied to external surfaces of the V-block12, more than one magnetic strip may be present on an external surface of the V-block12.
• Referring now toFIG. 7D, when the first selected strip and the second selected strip are removed to a desired degree, theneedle18 may be separated from the V-block12.
• As shown inFIG. 7E, themagnetic strips30A may be positioned on the V-block12 so that thestrips30A are oriented oppositely to those shown inFIGS. 7A through 7D.
• FIGS. 8A-8C are respective cross sectional views of aneedle guidance device50 according to yet another embodiment of the invention. Theneedle guidance device50 includes a pair of opposingmetal cores54 having agap58A and agap58B between theferromagnetic cores54. Themetal cores54 are generally semi-circularly shaped and may be made of any metal or metal alloy suitable for conveying a magnetic field, such as a ferromagnetic or ferrite material. Amagnet56 is removably positionable within a selected one of thegaps58A and58B. For purposes of illustration, themagnet56 is positioned in the gap56A. When themagnet56 is positioned within a selected one of thegaps58A and58B, a magnetic field is communicated along thecores54 from thegap58A to thegap58B. Thegap58B is configured to accept aneedle18 so that theneedle18 will be retained in thegap58B by the magnetic fields communicated from gap56A. As shown inFIG. 8A, the lines of the magnetic force are conveyed across thespace58B. Referring briefly now toFIG. 8B, theneedle18 is held within thegap58B. Accordingly, theneedle18 will be retained within thegap58B while themagnet56 is positioned withingap58A. Thegap58B progressively narrows to accommodate needles having variable diameters. Turning now toFIG. 8C, as themagnet56 is moved outwardly from thegap58A of theneedle guidance device50, the magnetic field spanning thegap58B is correspondingly reduced. Accordingly, theneedle18 positioned within thegap58B may be gradually released from theneedle guidance device50.
• FIGS. 9A-9D are respective cross sectional views of aneedle guidance device60 according to yet still another embodiment of the invention. With reference now toFIG. 9A, theneedle guidance device60 includes amagnet66 that is configured to be rotated within thegap58A. InFIG. 9A, themagnet66 is shown in a first position so that the magnetic lines of force are communicated along theferromagnetic cores54. Accordingly, a magnetic field is established within thegap58B, so that theneedle18 is retained within thegap58B, as shown inFIG. 9B. InFIG. 9C, themagnet66 is rotated to a second position so that the magnetic lines of force are generally directed away from theferromagnetic cores54. Accordingly, the attractive force that retains theneedle18 within thegap58B is reduced so that theneedle18 may be moved away from thegap58B.
• FIG. 10A is an isometric view of theneedle guidance device50 ofFIGS. 8A through 8C. In this schematic view, theneedle18 is held into thegap58B by the magnetic field generated by themagnet56. Theneedle18 is retained from moving through thegap58B and into an internal region of thedevice50 by providing beveled walls within thegap58B that have a minimum distance “d” so that the beveled walls interfere with further movement of theneedle18 through thegap58B since the distance “d” is generally selected to be smaller than a diameter of theneedle18. Referring now toFIG. 10B, method of disengagement of theneedle18 from thegap58B is shown. The disengagement of theneedle18 from theneedle guidance device50 includes moving themagnet56 upwardly and away from thecores54. Correspondingly, a reduction in magnetic holding force occurs within thegap58B so that theneedle18 may be removed from theneedle guidance device50.
• FIG. 10C shows an alternate method for disengagement of theneedle18 from theneedle guidance device50. Moving themagnet56 longitudinally along thegap58A so that the magnetic force across thegap58B is proportionately reduced effects the disengagement of theneedle18. Depending upon the relative strength of themagnet56, the composition of thecores54 and the material used to fabricate the needle, a user removing themagnet56 may find that the magnetic holding force is sufficiently reduced to permit non-injurious disengagement of theneedle18 from thegap58B of theneedle guidance device50 when themagnet56 is only partially disengaged from thegap58A. Alternately, the user may be required to completely remove themagnet56 from thegap58A in order to release theneedle18 from thedevice50.
• FIG. 11A is an isometric view of theneedle guidance device60 that shows theneedle18 held in position by the rotatingmagnet66. In this case, therotatable magnet66 is in the vertical position within thegap58A, and the magnetic forces hold theneedle18 within thegap58B.
• FIG. 11B shows a completion of the disengagement process fromFIG. 11A. Therotatable magnet66 is rotated to a horizontal position as indicated by the crosshatched arrow within thegap58A. This rotation causes either a reduction of retentive magnetic forces spanning across thegap58B or generation of repulsive forces. As indicated by the downward arrow, theneedle18 becomes disengagable from theneedle guidance device60 and eventually separates from thegap58B.
• FIG. 12A is an isometric view of aneedle guidance device70, according to another embodiment of the invention. Thedevice70 includes twoferromagnetic core assemblies54 that are longitudinally spaced apart and share a common movablepermanent magnet56 configured to engagerespective gaps58A in thecore assemblies54. Themagnet56 may either be slidably disengaged from eachferromagnetic core assembly54 either longitudinally or it may be removed from thegap58A by moving themagnet56 in a radial direction and away from thecore assemblies54. In either event, the progressive removal ofpermanent magnet56 from therespective gaps58A causes a progressive reduction in magnetic fields across thegaps58B. Accordingly, a user may advantageously select a suitable retentive force for theneedle18.
• FIG. 12B shows a disengagement of the operation in the orthogonal displacement. Here, theneedle guidance device70 is in a disengagement process where thepermanent magnet56 is removed 90° orthogonal to thespaces58A, to eachferrite core assembly54. Removal as previously mentioned of apermanent magnet56 causes a diminution magnetic retentive forces across thegap58B resulting in a progressively easier disengagement force to be affected to theneedle18.
• FIG. 13A shows aneedle guidance80 being an electromagnetic alternate embodiment to thepermanent magnet embodiment70. Thiselectromagnetic embodiment80 includes a DC power assembly that has apower source82, avariable resistor84 connected to thepower source82, in communication with a coil winding (not shown—seeFIG. 13B below) electrically connected with thesource82 andresistor84 via awire86. Thewire86 is connected with the coil winding (not shown) that is wrapped within thegroove158 of theelectromagnet156. Theelectromagnet156 is a non-permanent electromagnet that respectfully occupies thespaces58A ofmetal cores54. The dashedarrow84A within thevariable resistor84 shows a resistor position when there is sufficient power that is delivered to the core winding occupying thegrove158 to induce a magnetic field of sufficient strength to hold theneedle18 acrossrespective gaps58B of each iron or othermetal core assembly54 that is able to convey the magnetic flux fields generated by theelectromagnet156. Reducing the power indicated by thesolid arrow84B resistor position progressively causes a reduction of magnetic force due to the diminution of current and/or voltage applied to the windings occupying thegrove158. Eventually the magnetic power is progressively lessened such that an applied disengagement force by a user permits the removal or non-injurious disengagement of theneedle18, as indicated by the downward arrow, from thegaps58B of theguidance device80.
• FIG. 13B is an isometric view schematically depicting the electromagnet ofFIG. 13A. Within thegrooves158 of the he electromagnet156 is a coil winding88. Application of electrical power by theDC power supply82 through thevariable resistor84 results in a magnetic force generated by theelectromagnet156 in proportion to the amount of electrical power delivered to the coil winding88. North, N and South, S poles are formed along theelectromagnet156. As the power is gradually lessened between the84A and84B resistor positions, the retentive magnetic force field generated along theelectromagnet156 is accordingly lessened.
• As previously described for the removal of the magnetic strip embodiments and the permanent magnets and the electromagnet needle guidance devices as previously described provides a means for holding a selected cannula such that the cannula is controllably restricted in motion substantially along one dimension. The user may either manipulate the amount of magnetic strips to vary the magnetic power by the permanent magnets or adjust power to electromagnets so that a user may progressively overcome the retentive forces still applied to theneedle18 and effect the extraction or disengagement of theneedle18 from the respective needle guidance devices in a non-injurious way from a patient or other subject.
• FIGS. 14-20B are partial isometric views that depict various embodiments of the present invention coupled to anultrasound transceiver100. In the description that follows, it is understood that the various embodiments may be removably coupled to theultrasound transceiver100, or they may be permanently coupled to thetransceiver100. It is also understood that, although an ultrasound transceiver is described in the following description and shown in the following figures, the various embodiments may also be incorporated into other imaging devices.
• FIG. 14 is a partial isometric side view the V-Block40A ofFIG. 6A andFIG. 6B coupled to anultrasound transceiver101 to form anassembly100. Theultrasound transceiver101 has theneedle guidance device40A coupled to atransducer housing104 of thetransceiver101 using abridge108. Theneedle guidance device40A may be fixedly coupled to thehousing104, or thedevice40A may be removably coupled to thehousing104. In either case, thetransceiver100 also includes atrigger102, adisplay103, ahandle106, and atransducer dome112. Upon pressing thetrigger102, anultrasound scancone116 emanates from thetransducer dome112 that penetrates a subject or patient. Thescancone116 is comprised of a radial array of scan planes118. Within thescanplane118 are scanlines (not shown) that may be evenly or unevenly spaced. Alternatively, thescancone116 may be comprised of an array of wedged distributed scancones or an array of 3D-distributed scanlines that are not necessarily confined to a givenscan plane118. As shown, thescancone116 is radiates about thetransducer axis11 that bisects thetransducer housing104 anddome112.
• FIG. 15 is a partial isometric, side view of theneedle guidance device50 ofFIG. 8A,FIG. 8B andFIG. 8C coupled to theultrasound transceiver101 to form anassembly120. Theultrasound transceiver101 has theneedle guidance device50 mounted to thetransducer housing104 using thebridge108 ofFIG. 14. Thedevice50 may be fixedly or removably coupled to thehousing104. Ascan cone116 is similarly projected from thetransceiver101. Various aiming aids may be placed on theneedle guidance device50 to assist a user in aiming the insertion of a needle that is held by a magnetic force to slide within thegap58B.
• FIG. 16 is a partial isometric view of aneedle guidance device90 that may be removably coupled to thehousing104 of anultrasound transceiver101, according to another embodiment of the invention. Theneedle guidance device90 is attached to anengagement wedge92. Theengagement wedge92 slidably and removably attaches with theslot holder94 that is positioned on a selected portion of thehousing104. Various aiming aids may be placed on theneedle guidance device90 to assist a user in aiming the insertion of a needle that is held by a magnetic force to slide within thegap58B.
• FIG. 17 is a partial isometric view of aneedle guidance device130 according to another embodiment of the invention. Thedevice130 is configured to be positioned within atransceiver housing132. A pair ofmagnets134 and136 are positioned on arotational shaft137 that projects into thehousing132. Themagnets134 and136 provide an attractive force on theneedle18 when themagnets134 and136 are aligned with theneedle18. When themagnets134 and136 are rotated away from alignment (by manually rotating awheel139 coupled to the shaft138) with theneedle18, the attractive force on theneedle18 is reduced, thus allowing theneedle18 to be moved relative to thehousing132.
• FIG. 18A is a side view of an ultrasound scanner having amagnetic guide assembly144, according to an embodiment of the invention. Theguidance assembly144 includes thetransceiver101 in which aneedle18 withreservoir19 is held within aferrite housing144. Theferrite housing144 is secured totransducer housing104 by a clip-onclasp142.
• FIG. 18B is an isometric view and exploded view of components of theassembly144 ofFIG. 18A. In the exploded view, theguidance assembly144 is seen in greater detail. Theferrite housing144 receivesferrite cores146 and150. Rotable within the space defined by theferrite core146 andgap58A offerrite cores150 is arotatable magnet148. Located between the clip-onclasp142 and theferrite housing144 is an articulatingbridge143. The articulatingbridge143 allows the user to alter the entry angle of theneedle18 into the patient relative to thetransducer axis11 as illustrated inFIG. 14. Rotating themagnet148 alters the magnetic holding power togap58B betweenferrite cores150.
• FIG. 19A is a side view of alternate embodiment shown inFIG. 18A that uses a sliding magnet. Aguidance assembly170 includes thetransceiver101 in which aneedle18 withreservoir19 is held within a ferrite housing145. The ferrite housing145 is secured totransducer housing104 by a clip-onclasp142 and articulatingbridge143. The ferrite housing145 is configured to receive three components.
• FIG. 19B is an isometric view and exploded view of the components of thedevice170 ofFIG. 19A. In the exploded view theguidance assembly170 is seen in greater detail. The ferrite housing145 receives twoferrite cores172 and aslidable magnet176. Theslidable magnet176 is moveable within the space56A defined by theferrite cores172. Opposite the space56A is space56B that receives theneedle18. The articulatingbridge143 allows the user to alter the entry angle of theneedle18 into the patient or subject relative to thetransducer axis11 as illustrated inFIG. 14. Sliding themagnet176 alters the magnetic holding power togap58B betweenferrite cores172.
• FIG. 20A is a side view of alternate embodiment of thedevice170 ofFIG. 19A utilizing a pulling magnet. Aguidance assembly180 includes thetransceiver101 in which aneedle18 withreservoir19 is held within aferrite housing182. Theferrite housing182 is secured totransducer housing104 by a clip-onclasp142 and articulatingbridge143. The ferrite housing145 is configured to receive three components.
• FIG. 20B is an isometric view and exploded view of components of thedevice180 ofFIG. 20A. In the exploded view theguidance assembly180 is seen in greater detail. Theferrite housing182 receives twoferrite cores188 and atrigger receiver186. Thetrigger receiver186 receivers thetrigger190 that has amagnet frame191. Themagnet frame191 retains themagnet192. Themagnet192 is snap-fitted into themagnet frame191 of thetrigger190. The magnet-loadedtrigger190 is slidably placed into thetrigger receiver186. Thetrigger receiver186 guides the magnet-loadedtrigger190 within thegap58B defined by the twoferrite cores188. Pulling the magnet-loadedtrigger190 alters the magnetic holding power to gap58B receiving theneedle18 located opposite thegap58A betweenferrite cores188.
• An example embodiment includes a system and method using single or multiple cameras for tracking and displaying the movement of a needle or cannula before and/or during insertion into a blood vessel or other sub-dermal structure and subsequent movements therein. A needle or a cannula-fitted needle may be detachably mounted to an ultrasound transceiver in signal communication with a computer system and display configured to generate ultrasound-acquired images and process images received from the single or multiple cameras. Along the external surfaces of the needle or cannula may be fitted optical reflectors that may be discernable in the camera images. The ultrasound transceiver may be secured against a subject's dermal area adjacent to a sub-dermal region of interest (ROI). Optical signals may be reflected towards the single or multiple cameras by the needle or cannula embedded reflectors and conveyed to the computer system and display. The trajectories of the needle or cannula movements may be determined by data analysis of the reflector signals detected by the cameras. The trajectories of needle or cannula having one or more reflectors may be overlaid onto the ultrasound images to provide alignment coordinates for insertion of the needle or cannula fitted needle into the ROI along a determined trajectory.
• An example embodiment of the present invention generally includes an ultrasound probe attached to a first camera and a second camera. The example embodiment also generally includes a processing and display generating system that may be in signal communication with the ultrasound probe, the first camera, and/or the second camera. Typically, a user of the system scans tissue containing a target vein using the ultrasound probe and a cross-sectional image of the target vein may be displayed. The first camera captures and/or records a first image of a medical object to be inserted, such as a cannula for example, in a first direction and the second camera captures and/or records a second image of the cannula in a second direction orthogonal to the first direction. The first and/or the second images may be processed by the processing and display generating system along with the relative positions of the ultrasound probe, the first camera, and/or the second camera to determine the trajectory of the cannula. A representation of the determined trajectory of the cannula may be then displayed on the ultrasound image.
• FIG. 1 is a diagram illustrating a side view of one embodiment of the present invention. A two-dimensional (2D)ultrasound probe10 may be attached to afirst camera14 that takes images in a first direction. Theultrasound probe10 may be also attached to asecond camera18 via amember16. In other embodiments, themember16 may link thefirst camera14 to thesecond camera18 or themember16 may be absent, with thesecond camera18 being directly attached to a specially configured ultrasound probe. Thesecond camera18 may be oriented such that thesecond camera18 takes images in a second direction that may be orthogonal to the first direction of the images taken by thefirst camera14. The placement of thecameras14,18 may be such that they can both take images of acannula20 when thecannula20 may be placed before thecameras14,18. A needle may also be used in place of a cannula. Thecameras14,18 and theultrasound probe10 may be geometrically interlocked such that thecannula20 trajectory can be related to an ultrasound image. InFIG. 1, thesecond camera18 may be behind thecannula20 when looking into the plane of the page. In an embodiment, thecameras14,18 take images at a rapid frame rate of approximately 30 frames per second. Theultrasound probe10 and/or thecameras14,18 may be in signal communication with a processing anddisplay generating system61 described inFIGS. 7 and 8 below.
• In typical operation, a user first employs theultrasound probe10 and the processing anddisplay generating system61 to generate a cross-sectional image of a patient's arm tissue containing a vein to be cannulated (“target vein”)19. This could be done by one of the methods disclosed in the patents, patent publications and/or patent applications which are herein incorporated by reference, such as, for example, U.S. patent application Ser. No. 11/460,182 filed Jul. 26, 2006. The user then identifies thetarget vein19 in the image using methods such as simple compression which differentiates between arteries and/or veins by using the fact that veins collapse easily while arteries do not. After the user has identified thetarget vein19, theultrasound probe10 may be affixed to the patient's arm over the previously identifiedtarget vein19 using amagnetic tape material12, for example. Theultrasound probe10 and the processing anddisplay generating system61 continue to generate a 2D cross-sectional image of the tissue containing thetarget vein19. Images from thecameras14,18 may be provided to the processing anddisplay generating system61 as thecannula20 may be approaching and/or entering the arm of the patient.
• The processing anddisplay generating system61 locates thecannula20 in the images provided by thecameras14,18 and determines the projected location at which thecannula20 will penetrate the cross-sectional ultrasound image being displayed. The trajectory of thecannula20 may be determined in some embodiments by using image processing to identify bright spots corresponding to micro reflectors previously machined into the shaft of thecannula20 or a needle used alone or in combination with thecannula20. Image processing uses the bright spots to determine the angles of thecannula20 relative to thecameras14,18 and then generates a projected trajectory by using the determined angles and/or the known positions of thecameras14,18 in relation to theultrasound probe10. In other embodiments, determination of thecannula20 trajectory may be performed using edge-detection algorithms in combination with the known positions of thecameras14,18 in relation to theultrasound probe10, for example.
• The projected location may be indicated on the displayed image as a computer-generated cross-hair66 (shown inFIG. 7), the intersection of which may be where thecannula20 is projected to penetrate the image. In other embodiments, the projected location may be depicted using a representation other than a cross-hair. When thecannula20 does penetrate the cross-sectional plane of the scan produced by theultrasound probe10, the ultrasound image confirms that thecannula20 penetrated at the location of the cross-hair66. This gives the user a real-time ultrasound image of thetarget vein19 with an overlaid real-time computer-generated image of the position in the ultrasound image that thecannula20 will penetrate. This allows the user to adjust the location and/or angle of thecannula20 before and/or during insertion to increase the likelihood they will penetrate thetarget vein19. In other embodiments, the ultrasound image and/or the computer-generated cross-hair may be displayed in near real-time. In an example embodiment, this allows a user to employ normal “free” insertion procedures while having the added knowledge of knowing where thecannula20 trajectory will lead.
• FIG. 2 is a diagram illustrating a top view of the embodiment shown inFIG. 1. It is more easily seen from this view that thesecond camera18 may be positioned behind thecannula20. The positioning of thecameras14,18 relative to thecannula20 allows thecameras14,18 to capture images of thecannula20 from two different directions, thus making it easier to determine the trajectory of thecannula20.
• FIG. 3 is diagram showing additional detail for aneedle shaft22 to be used with one embodiment of the invention. Theneedle shaft22 includes a plurality ofmicro corner reflectors24. Themicro corner reflectors24 may be cut into, or otherwise affixed to or embedded in, theneedle shaft22 at defined intervals Δl in symmetrical patterns about the circumference of theneedle shaft22. Themicro corner reflectors24 could be cut with a laser, for example.
• FIGS. 4A and 4B are diagrams showing close-up views of surface features of theneedle shaft22 shown inFIG. 3.FIG. 4A shows a first input ray with a first incident angle of approximately 90° striking one of themicro corner reflectors24 on theneedle shaft22. A first output ray is shown exiting themicro corner reflector24 in a direction toward the source of the first input ray.FIG. 4B shows a second input ray with a second incident angle other than 90° striking a micro corner reflector25 on theneedle shaft22. A second output ray is shown exiting the micro corner reflector25 in a direction toward the source of the second input ray.FIGS. 4A and 4B illustrate that themicro corner reflectors24,25 are useful because they tend to reflect an output ray in the direction from which an input ray originated.
• FIG. 5 is a diagram showing imaging components for use with theneedle shaft22 shown inFIG. 3 in accordance with an example embodiment of the invention. The imaging components are shown to include afirst light source26, a secondlight source28, alens30, and asensor chip32. The first and/or secondlight sources26,28 may be light emitting diodes (LEDs), for example. In an example embodiment, thelight sources26,28 are infra-red LEDs. Use of an infra-red source is advantageous because it is not visible to the human eye, but when an image of theneedle shaft22 is recorded, the image can show strong bright dots where themicro corner reflectors24 may be located because silicon sensor chips are sensitive to infra-red light and themicro corner reflectors24 tend to reflect output rays in the direction from which input rays originate, as discussed with reference toFIGS. 4A and 4B. In alternative embodiments, a single light source may be used. Although not shown, thesensor chip32 may be encased in a housing behind thelens30 and thesensor chip32 andlight sources26,28 may be in electrical communication with the processing anddisplay generating system61 shown inFIG. 7 below. Thesensor chip32 and/or thelens30 form a part of the first andsecond cameras14,18 in some embodiments. In an example embodiment, thelight sources26,28 may be pulsed on at the time thesensor chip32 captures an image. In other embodiments, thelight sources26,28 may be left on during video image capture.
• FIG. 6 is a diagram showing a representation of animage34 produced by the imaging components shown inFIG. 5. Theimage34 may include aneedle shaft image36 that corresponds to a portion of theneedle shaft22 shown inFIG. 5. Theimage34 also may include a series ofbright dots38 running along the center of theneedle shaft image36 that correspond to themicro corner reflectors24 shown inFIG. 5. Acenter line40 is shown inFIG. 6 that runs through the center of thebright dots38. Thecenter line40 may not appear in the actual image generated by the imaging components, but is shown in the diagram to illustrate how an angle theta (θ) could be obtained by image processing to recognize thebright dots38 and determine a line through them. The angle theta represents the degree to which theneedle shaft22 may be inclined with respect to areference line42 that may be related to the fixed position of thesensor chip32.
• FIG. 7 is a system diagram of an embodiment of the present invention and shows additional detail for the processing anddisplay generating system61 in accordance with an example embodiment of the invention. Theultrasound probe10 is shown connected to the processing and display generating system via M control lines and N data lines. The M and N variables are for convenience and appear simply to indicate that the connections may be composed of one or more transmission paths. The control lines allow the processing anddisplay generating system61 to direct theultrasound probe10 to properly perform an ultrasound scan and the data lines allow responses from the ultrasound scan to be transmitted to the processing anddisplay generating system61. The first andsecond cameras14,18 are also each shown to be connected to the processing anddisplay generating system61 via N lines. Although the same variable N is used, it is simply indicating that one or more lines may be present, not that each device with a label of N lines has the same number of lines.
• The processing anddisplay generating system61 may be composed of adisplay64 and ablock62 containing a computer, a digital signal processor (DSP), and analog to digital (A/D) converters. As discussed forFIG. 1, thedisplay64 can display a cross-sectional ultrasound image. The computer-generatedcross hair66 is shown over a representation of a cross-sectional view of thetarget vein19 inFIG. 7. Thecross hair66 consists of an x-crosshair68 and a z-crosshair70. The DSP and the computer in theblock62 use images from thefirst camera14 to determine the plane in which thecannula20 will penetrate the ultrasound image and then write the z-crosshair70 on the ultrasound image provided to thedisplay64. Similarly, the DSP and the computer in theblock62 use images from thesecond camera18, which may be orthogonal to the images provided by thefirst camera14 as discussed forFIG. 1, to write the x-crosshair68 on the ultrasound image. In other embodiments, the DSP and the computer in theblock62 may use images from both thefirst camera14 and thesecond camera18 to write each of the x-crosshair68 and the z-crosshair70 on the ultrasound image. In still other examples, images from thecameras14,18 may be used separately or in combination to write thecrosshairs68,70 or other representations of where thecannula20 is projected to penetrate the ultrasound image.
• FIG. 8 is a system diagram of an example embodiment showing additional detail for theblock62 shown inFIG. 2. Theblock62 includes a first A/D converter80, a second A/D converter82, and a third A/D converter84. The first A/D converter80 receives signals from theultrasound probe10 and converts them to digital information that may be provided to aDSP86. The second and third A/D converters82,84 receive signals from the first andsecond cameras14,18 respectively and convert the signals to digital information that may be provided to theDSP86. In alternative embodiments, some or all of the A/D converters are not present. For example, video from thecameras14,18 may be provided to theDSP86 directly in digital form rather than being created in analog form before passing through A/D converters82,84. TheDSP86 may be in data communication with acomputer88 that includes a central processing unit (CPU)90 in data communication with amemory component92. Thecomputer88 may be in signal communication with theultrasound probe10 and may be able to control theultrasound probe10 using this connection. Thecomputer88 may be also connected to thedisplay64 and may produce a video signal used to drive thedisplay64. In still other examples, other hardware components may be used. A field programmable gate array (FPGA) may be used in place of the DSP, for example. Or, an application specific integrated circuit (ASIC) may replace one or more components.
• FIG. 9 is a flowchart of a process of displaying the trajectory of a cannula in accordance with an embodiment of the present invention. The process is illustrated as a set of operations shown as discrete blocks. The process may be implemented in any suitable hardware, software, firmware, or combination thereof. As such the process may be implemented in computer-executable instructions that can be transferred from one computer to a second computer via a communications medium. The order in which the operations are described is not to be necessarily construed as a limitation. First, at ablock100, an ultrasound image of a vein cross-section may be produced and/or displayed. Next, at ablock110, the trajectory of a cannula may be determined. Then, at ablock120, the determined trajectory of the cannula may be displayed on the ultrasound image.
• FIG. 10 is a flowchart of a process showing additional detail for theblock110 depicted inFIG. 9. The process is illustrated as a set of operations shown as discrete blocks. The process may be implemented in any suitable hardware, software, firmware, or combination thereof. As such the process may be implemented in computer-executable instructions that can be transferred from one computer to a second computer via a communications medium. The order in which the operations are described is not to be necessarily construed as a limitation. Theblock110 includes ablock112 where a first image of a cannula may be recorded using a first camera. Next, at ablock114, a second image of the cannula orthogonal to the first image of the cannula may be recorded using a second camera. Then, at ablock116, the first and second images may be processed to determine the trajectory of the cannula.
• FIG. 11 schematically depicts an alternative embodiment of a needle having a distribution of reflectors located near the bevel of the needle. Aneedle shaft52 includes abevel54 that may be pointed for penetration into the skin to reach the lumen of a blood vessel. Theneedle shaft52 also includes a plurality ofmicro corner reflectors24. Themicro corner reflectors24 may be cut into theneedle shaft52 at defined intervals Δl in symmetrical patterns about the circumference of theneedle shaft52. In an example, themicro corner reflectors24 may be cut with a laser and serve to provide light reflective surfaces for monitoring the insertion and/or tracking of the trajectory of thebevel54 into the blood vessel during the initial penetration stages of theneedle52 into the skin and/or tracking of thebevel54 motion during guidance procedures.
• While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. For example, a three-dimensional ultrasound system could be used rather than a 2D system. In addition, different numbers of cameras could be used along with image processing that determines thecannula20 trajectory based on the number of cameras used. The twocameras14,18 could also be placed in a non-orthogonal relationship so long as the image processing was adjusted to properly determine the orientation and/or projected trajectory of thecannula20. The radiation emitting from thelight sources26,28 may be of a frequency and intensity that may be sufficiently penetrating in tissue to permit reflection of sub-dermal locatedreflectors24 to thedetector sensor32. Thesensor32 may be suitably filtered to optimize detection of sub-dermal reflected radiation from thereflectors24 so that sub-dermal trajectory tracking of theneedles22,52 orcannulas20 having one ormore reflectors24 may be achieved. Also, an embodiment of the invention could be used for needles and/or other devices such as trocars, stylets, or catheters which are to be inserted in the body of a patient. Additionally, an embodiment of the invention could be used in places other than arm veins. Regions of the patient's body other than an arm could be used and/or biological structures other than veins may be the focus of interest.
• While various embodiments of the invention have been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. For example, electromagnetic strips may be removably attached to V-blocks and the magnetic power controlled by an electric circuit applied to the electromagnetic strips. Permanent magnets used in the various embodiments may be of any metal able to generate and communicate a magnetic force, for example, Iron, Iron alloys, and Neodymnium based magnets. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.

Claims (25)

1. An imaging guided device for placing a cannula attached to a magnetically responsive needle at a targeted location, the device comprising:

an imaging probe operationally configured with imaging system to present an image;

an attachment connected with the imaging probe, the attachment comprising:

a block having at least one magnet to releasably retain the needle by alternating the magnetic force of the magnet applied to the needle,

wherein the needle is inserted to and removed from the targeted location as determined in the image at a user adjusted retentive magnetic force, leaving the cannula in place at the targeted location after removal of the needle.

2. The device ofclaim 1, wherein the magnet comprises at least one removable strip.

3. The device ofclaim 1, wherein the magnet comprises two removable strips approximately orthogonal to each other.

4. The device ofclaim 3, wherein the removable strip includes a plurality of magnets having substantially similar magnetic power.

5. The device ofclaim 3, wherein the removable strip includes a plurality of magnets having substantially different magnetic power.

6. The device ofclaim 5, wherein the removable strip includes an inner magnetic core and an outer magnetic perimeter.

7. The device ofclaim 1, wherein the magnet includes a ferrite core having a first gap to engage a moveable magnet bar and a second gap to receive the magnetically responsive needle.

8. The device ofclaim 7, wherein the moveable magnet bar is slidable within the first gap.

9. The device ofclaim 7, wherein the moveable magnet bar is translocatable from the first gap.

10. The device ofclaim 7, wherein the moveable magnet bar is rotatable within the first gap.

11. The device ofclaim 1, wherein the magnet includes a magnetic core having a first gap to engage a moveable magnet bar and a second gap to receive the magnetically responsive needle.

12. The device ofclaim 11, wherein the moveable magnet bar is rotatable within the first gap.

13. A system for visualizing a medical object trajectory comprising:

a processing and display generating system;

an ultrasound probe for scanning tissue in signal communication with the processing and display generating system; and

at least one camera for capturing at least one image of a medical object in signal communication with the processing and display generating system,

wherein the processing and display generating system is configured to process signals received from the ultrasound probe, display an ultrasound image of the tissue, process signals received from the at least one camera to determine a trajectory of the medical object, and display a representation of the determined trajectory of the medical object on the ultrasound image.

14. The system ofclaim 13, wherein the at least one camera includes a first camera that takes images of the medical object in a first direction and a second camera that takes images of the medical object in a second direction.

15. The system ofclaim 14, wherein the first and second cameras are in a fixed position relative to the ultrasound probe.

16. The system ofclaim 15, wherein the second direction is orthogonal to the first direction.

17. The system ofclaim 14, wherein the medical object includes a cannula.

18. The system ofclaim 14, wherein the medical object includes a plurality of reflectors and wherein the processing and display generating system is configured to determine a trajectory of the medical object based on light reflected by the plurality of reflectors.

19. The system ofclaim 18, wherein the medical object includes a needle having a bevel, at least one of the reflectors is located near the bevel, and the processing and display generating system is configured to determine a trajectory of the bevel.

20. The system ofclaim 19, wherein the processing and display generating system is configured to display a cross-sectional image of a target vein located within the scanned tissue on the ultrasound image and wherein the processing and display generating system is configured to display a representation of the determined trajectory of the medical object on the ultrasound image.

21. The system ofclaim 20, wherein the representation of the determined trajectory includes cross-hairs.

22. The system ofclaim 21, further comprising an illumination source for illuminating the medical object during image capture.

23. The system ofclaim 22, wherein the illumination source includes infrared light emitting diodes.

24. The system ofclaim 14, wherein at least one of the first and second cameras are configured to capture images of a portion of the medical object when the portion is in a sub-dermal location.

25. A method for visualizing a medical object trajectory comprising:

scanning tissue using an ultrasound probe;

displaying an ultrasound image of the tissue;

capturing at least one image of a medical object using at least one camera;

processing the at least one image to determine a trajectory of the medical object; and

displaying a representation of the determined trajectory of the medical object on the ultrasound image.

Images