Device for the injection of medical preparations with CT/MRI monitoring

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.

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.

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.

DESCRIPTION OF PREFERRED EMBODIMENT

The embodiment of the device as shown inFIGS. 1aand1bcomprises an infusion needle1, which is connected to four one-way syringes5of a dosing apparatus6by way of a mixing chamber36, four check valves3, four hoses4and four pressure sensors2. The four one-way syringes5are removably disposed in a magazine7in the dosing apparatus6and are operable each by a drive9including a piston10, which is movable individually for each one-way syringe in both directions8. However, if a check valve3is arranged between the respective one-way syringe5and the infusion needle1, which prevents a return flow, actuation in both direction without reversal or exchange of the check valve3is not possible. During operation of a syringe the injection flow is continuously monitored by way of the advance movement of the piston10using a travel sensor11as well as the pressure measurement by the pressure sensor2. End switches12are provided for limiting the advance movement of the piston10in each of its two directions8of movement.

In contrast to the schematic representation ofFIG. 1a, in the perspective representation ofFIG. 1b, the travel sensor11is arranged below the piston10and moves the pistons10by means of a carrier17(see alsoFIG. 2). Furthermore, the travel sensor11of 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 sensors11ofFIG. 1b.

FIG. 2shows an embodiment of the dosing apparatus6in a perspective cross-sectional representation with a changing magazine7, the one-way syringes5with pistons10and the drive9of several parts. In the embodiment shown, the drive comprises an electric motor15, which moves the piston10by way of a worm drive16with a syringe carrier17connected to each syringe piston10.

If the dosing apparatus6is 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 needle1is engaged by a reversably operable needle holder13as shown inFIG. 1a. The needle holder13is supported on an operable displacing device or linear drive14, which is adjustable axially with the injection needle1. In this way, the injection needle1is movable together with the needle holder13over a certain travel distance. If the injection needle1is to be further advanced, the needle holder13is released and the displacing device14is moved back without the injection needle1and the needle1is then again engaged at a rearward position in order to further advance the needle1. 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 needle1. 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 needle1between the needle holder13and the point of insertion into a patient'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. 3aand3bshow the injection needle advancing arrangement without injection needle in a sectional view, andFIGS. 4aand4bshow it in a perspective view, wherein the respective “a” designated figures show the needle holder13in a retracted position and the “b” designated figures show the needle holder13in an advanced position. The displacement device consists of two slide members18and a rack19which are connected to a needle holder13and guided in the housing20on two tracks21connected to the housing20of the needle advancing arrangement as well as a guide structure22. In the embodiment shown the adjustment movement is achieved by a worm drive23, which is operated by an electric motor25by way of a belt24.

The position of the needle holder13is determined in the embodiment shown by way of a rotary potentiometer37with a pinion, which measures the translational movement of the needle holder13in the track21in the guide structure22by way of a rack.

The injection needle is oriented in the housing20and guided in the housing20in axial direction by guide ledges26. The mixing chamber36shown inFIGS. 1aand1bserves as holder for the injection needle1and the mixing chamber36is therefore provided with corresponding guide grooves27(seeFIG. 1aand1b). Alternatively, the mixing chamber36may 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 housing20is open in the area of the guide ledges26so that this area is accessible for the insertion of the injection needle into the needle advancing arrangement and also for access to the check valves3and the hoses4from above, below and from the sides. It furthermore permits the physician to observe the needle insertion procedure.

FIG. 5shows a section through the needle holder13. The holder consists mainly of the two jaws271, which are guided by two guide pins28and which are moved in a synchronized motion in opposite directions by a worm drive29. The worm drive29is driven by an electric motor31by way of a belt30, the movement of the jaws27iaway from each other is limited by an end switch32for de-energizing the electric motor31.

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 needle1and the needle holder13are, by design, connected to the first part which can be sterilized and the advancing or displacing device14is 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 housing20of the injection needle advancing arrangement is supported, as shown inFIG. 6, on a C-like curved guide structure33according to the state of the art and is movable thereon by a motor and is positioned on a carrier34, under the control of a manipulator, above a patient35resting below. The curved C-shaped guide structure33which has a center of curvature connecting with the needle insertion point38and the manipulator operated pivot structure for the carrier34, 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 point38, through which the injection needle can be inserted from various directions. Furthermore, the dosing apparatus6may be mounted on the carrier34close 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 structure33, 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 sensor39is mounted on the carrier34which, by means of a support structure40is mounted at the level of the needle insertion point38such 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 point38can be approached by the needle at an exact surface location for example the surface of the skin of the patient35. The patient35can therefore be prepared by the contact with the sensor39on the skin for the expected piercing whereby the chances of the patient twitching upon piercing of the skin are substantially reduced. The sensor39consequently 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.