Abstract:
In a device for the injection of medical preparations, into a patients body during an examination in a Computer Tomograph (CT) or in a Magnetic Resonance Tomograph (MRT) or endoscopically, including an injection needle supported by an injection-needle advancing arrangement for insertion of the injection needle into the patients body and the concurrent injection of medications with a separate dosing apparatus, a hose with a check valve for the one-way transport of the medical preparations from the dosing apparatus into the injection needle, as well as a pressure sensor for monitoring the infusion, the injection needle advancing arrangement comprises a needle holder and a linear drive for the movement of the needle holder in parallel with the injection needle and the dosing apparatus has geometric dimensions and consists of materials permitting its insertion into the CT or MRT together with the patient.

Description:
This is a Continuation-in-Part Application of international patent application PCT/EP01/06996 filed on 21 Jun. 2001 and claiming the priority of German patent application 100 30 620.9 filed 28 Jun. 2000. 

   BACKGROUND OF THE INVENTION 
   The invention relates to a device for the injection of medical preparations, particularly medicines or contrast media, into a patients body during an examination in a computer tomograph, CT, magnetic resonance tomograph, MRT, or with an endoscope. The present invention comprises also the use of the apparatus in a magnetic resonance tomograph. 
   In the interventional radiology, the physician orients and controls his operative actions using imaging procedures such as the CT and MRT. During such a procedure, the patient generally rests on a stretcher, while the physician in charge supervises the procedure on a screen. With tomographic processes such as the CT- and MRT procedures, two-dimensional section images through the patients body, which are taken at small distances, are combined to provide a three-dimensional image, a so-called tomogram, of the patients body. The tomograms generated in this way show the internal organs, the tissue and the bone structures in detail. Any desirable section images can be generated in this way. In addition, individual section representations can be generated with the CT by tilting of the gantry or, with the MRT by a computer program. 
   Based on the tomographic data, the physician determines his accessing plan for the organ to be subsequently operated on and determines for an image-supported and manipulator-controlled medication administration the coordinates and dosing rates for the insertion of the injection needle and sends the data to the manipulator. 
   The publication Medrad Medizinische Systeme GmbH; Das Spectris MR-Injektions System, Brochure 1979 of Medrad Inc., USA discloses such a medication dosing system, wherein Medication or contrasting fluid is injected into a patients body by two 65 ml one-way syringes essentially by way of a hose and an injection needle. As it can be assumed from the technical data given, the one-way syringes are operated probably by an electric motor via linear drives. An obvious use of the medication dosing system in an MRT or CT under tomographic control is not mentioned in this publication although the size appears to be suitable for a use in the channel of a tomograph. 
   A manipulator-controlled medication dosing system, which is suitable for use in a CT or MRT however is not known. 
   It is the object of the present invention to provide a device for the injection of medical preparations which device is distinct with respect to the prior art in that it can be inserted into a tomograph as a complete unit and can be utilized therein on an imaging basis. 
   SUMMARY OF THE DISCLOSURE 
   In a device for the injection of medical preparations, into a patients body during an examination in a Computer Tomograph (CT) or in a Magnetic Resonance Tomograph (MRT) or endoscopically, including an injection needle supported by an injection-needle advancing arrangement for insertion of the injection needle into the patients body and the concurrent injection of medications with a separate dosing apparatus, a hose with a check valve for the one-way transport of the medical preparations from the dosing apparatus into the injection needle, as well as a pressure sensor for monitoring the infusion, the injection needle advancing arrangement comprises a needle holder and a linear drive for the movement of the needle holder in parallel with the injection needle and the dosing apparatus has geometric dimensions and consists of materials permitting its insertion into the CT or MRT together with the patient. 
   The device according to the invention for the injection of medical preparations will be explained below on the basis of the accompanying drawings showing an embodiment with four one-way syringes. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1   a  shows a component of the device for an injection of medical preparations in a schematic representation,
           FIG. 1   b  shows the device according to  FIG. 1   a  in a perspective representation but without the needle holder and the needle moving means,     FIG. 2 , shows the dosing arrangement  6  according to  FIG. 1   b  in a perspective sectional view,       
       FIGS. 3   a  and  3   b  show the injection needle advancing structure without injection needle in a sectional view with different positions of the needle holder, 
       FIGS. 4   a  and  4   b  show the injection needle advancing structure in a perspective view with different position of the needle holder, 
       FIG. 5  is a sectional representation of the needle holder, and 
       FIG. 6 , shows the positioning of the device as determined for an injection of medical preparations on a support above a patient. 
   

   DESCRIPTION OF PREFERRED EMBODIMENT 
   The embodiment of the device as shown in  FIGS. 1   a  and  1   b  comprises an infusion needle  1 , which is connected to four one-way syringes  5  of a dosing apparatus  6  by way of a mixing chamber  36 , four check valves  3 , four hoses  4  and four pressure sensors  2 . The four one-way syringes  5  are removably disposed in a magazine  7  in the dosing apparatus  6  and are operable each by a drive  9  including a piston  10 , which is movable individually for each one-way syringe in both directions  8 . However, if a check valve  3  is arranged between the respective one-way syringe  5  and the infusion needle  1 , which prevents a return flow, actuation in both direction without reversal or exchange of the check valve  3  is not possible. During operation of a syringe the injection flow is continuously monitored by way of the advance movement of the piston  10  using a travel sensor  11  as well as the pressure measurement by the pressure sensor  2 . End switches  12  are provided for limiting the advance movement of the piston  10  in each of its two directions  8  of movement. 
   In contrast to the schematic representation of  FIG. 1   a , in the perspective representation of  FIG. 1   b , the travel sensor  11  is arranged below the piston  10  and moves the pistons  10  by means of a carrier  17  (see also  FIG. 2 ). Furthermore, the travel sensor  11  of the shown embodiment is a linear potentiometer. Alternatively, opto-electronic travel distance measuring procedures can be used in connection with MRTs in an arrangement like that of the travel sensors  11  of  FIG. 1   b.    
     FIG. 2  shows an embodiment of the dosing apparatus  6  in a perspective cross-sectional representation with a changing magazine  7 , the one-way syringes  5  with pistons  10  and the drive  9  of several parts. In the embodiment shown, the drive comprises an electric motor  15 , which moves the piston  10  by way of a worm drive  16  with a syringe carrier  17  connected to each syringe piston  10 . 
   If the dosing apparatus  6  is to be used in connection with an MRT, exclusively non-magnetic components can be used for the dosing apparatus in order to avoid magnetic disturbances. To this end, pneumatic or hydraulic turbo drives, one-sided or double-sided operable hydraulic or pneumatic piston drives or, in a limited way, also Kardan-, Bowden cable- or cable drives, which extend to electrical or piezo drives disposed outside the MRT, may be used. 
   The injection needle  1  is engaged by a reversably operable needle holder  13  as shown in  FIG. 1   a . The needle holder  13  is supported on an operable displacing device or linear drive  14 , which is adjustable axially with the injection needle  1 . In this way, the injection needle  1  is movable together with the needle holder  13  over a certain travel distance. If the injection needle  1  is to be further advanced, the needle holder  13  is released and the displacing device  14  is moved back without the injection needle  1  and the needle  1  is then again engaged at a rearward position in order to further advance the needle  1 . Depending on the length of the injection needle this procedure can be repeated several times. 
   The special advantage of this injection needle linear drive or advancing arrangement is its compact design without the need for large piston or linear drives. As a result, the tight space in a channel particularly of an MRT is utilized in an advantageous manner without restriction of the advancing range of the injection needle  1 . The system furthermore permits placement of all system components closely to a patient, that is, within a CT or MRT so that the dead volume of the otherwise long medication supply lines is minimized. 
   Another advantageous of the injection needle advancing arrangement resides in the short exposed length of the needle  1  between the needle holder  13  and the point of insertion into a patient&#39;s body even for relatively long needles. The small exposed needle length reduces the chances of the needles, particularly of thin flexible needles, to buckle upon insertion into a body. 
     FIGS. 3   a  and  3   b  show the injection needle advancing arrangement without injection needle in a sectional view, and  FIGS. 4   a  and  4   b  show it in a perspective view, wherein the respective “a” designated figures show the needle holder  13  in a retracted position and the “b” designated figures show the needle holder  13  in an advanced position. The displacement device consists of two slide members  18  and a rack  19  which are connected to a needle holder  13  and guided in the housing  20  on two tracks  21  connected to the housing  20  of the needle advancing arrangement as well as a guide structure  22 . In the embodiment shown the adjustment movement is achieved by a worm drive  23 , which is operated by an electric motor  25  by way of a belt  24 . 
   The position of the needle holder  13  is determined in the embodiment shown by way of a rotary potentiometer  37  with a pinion, which measures the translational movement of the needle holder  13  in the track  21  in the guide structure  22  by way of a rack. 
   The injection needle is oriented in the housing  20  and guided in the housing  20  in axial direction by guide ledges  26 . The mixing chamber  36  shown in  FIGS. 1   a  and  1   b  serves as holder for the injection needle  1  and the mixing chamber  36  is therefore provided with corresponding guide grooves  27  (see  FIG. 1   a  and  1   b ). Alternatively, the mixing chamber  36  may be disposed on a separate carrier which, as a separate component, is provided with the necessary guide grooves. In this case, the mixing chamber is releasable from the injection needle advancing arrangement together with the injection needle and the hoses. The housing  20  is open in the area of the guide ledges  26  so that this area is accessible for the insertion of the injection needle into the needle advancing arrangement and also for access to the check valves  3  and the hoses  4  from above, below and from the sides. It furthermore permits the physician to observe the needle insertion procedure. 
     FIG. 5  shows a section through the needle holder  13 . The holder consists mainly of the two jaws  271 , which are guided by two guide pins  28  and which are moved in a synchronized motion in opposite directions by a worm drive  29 . The worm drive  29  is driven by an electric motor  31  by way of a belt  30 , the movement of the jaws  27   i  away from each other is limited by an end switch  32  for de-energizing the electric motor  31 . 
   For the use of the injection needle advancing structure on a patient in the channel of an MRT exclusively non-magnetic components can be used in order to avoid magnetic disturbances. Consequently, all electric motors must be replaced by pneumatic or hydraulic turbo-drives, piezo drives, single or double-action hydraulic or pneumatic piston drives or, in a limited way, by Kardan- or Bowden cables or cable drives connected to electric motors disposed remote from the MRT. 
   To facilitate sterilization, the injection needle advancing arrangement can comprise two parts wherein the injection needle  1  and the needle holder  13  are, by design, connected to the first part which can be sterilized and the advancing or displacing device  14  is connected to the second part which is not sterile. The first part is separated from the second part after each procedure and sterilized while another sterilized first part is mounted to the second part so that the device can be used again. 
   For use in the small space available for the device according to the invention in the CT or MRT, the housing  20  of the injection needle advancing arrangement is supported, as shown in  FIG. 6 , on a C-like curved guide structure  33  according to the state of the art and is movable thereon by a motor and is positioned on a carrier  34 , under the control of a manipulator, above a patient  35  resting below. The curved C-shaped guide structure  33  which has a center of curvature connecting with the needle insertion point  38  and the manipulator operated pivot structure for the carrier  34 , which is not shown, make it possible to pivot the injection needle advancing arrangement about all spatial degrees of freedom for example about a fixed needle insertion point  38 , through which the injection needle can be inserted from various directions. Furthermore, the dosing apparatus  6  may be mounted on the carrier  34  close to the injection needle advancing structure whereby the length of the hoses can be substantially reduced. Short hoses minimize pressure changes and elasticity effects on the medication in the hose and provide therefore for a more accurate dosing of the medications. 
   Alternatively, the effects of the C-like guide structure  33 , that is, the pivoting of the injection needle advancing structure or of another medical instrument can also be achieved by a motor-driven support joint or a rotating table in combination with a computer-based manipulator control. 
   In addition, a sensor  39  is mounted on the carrier  34  which, by means of a support structure  40  is mounted at the level of the needle insertion point  38  such that the measuring volume is disposed around the needle insertion point on the skin of the patient. The sensor may be for example an annular contact sensor in contact with an annular area around the needle insertion point. In this way, the insertion point  38  can be approached by the needle at an exact surface location for example the surface of the skin of the patient  35 . The patient  35  can therefore be prepared by the contact with the sensor  39  on the skin for the expected piercing whereby the chances of the patient twitching upon piercing of the skin are substantially reduced. The sensor  39  consequently monitors the movement of the patient. In addition, or in the alternative, the surface may be marked for recognition by sensors so that it can be recognized by optical detectors, which are not shown, and which can be brought to coincide with the insertion point under manipulator control.