DE20003349U1 - Device for the thermal treatment of biological tissue - Google Patents

Description

LMTB CLITT vl.O

Utility model

Applicant: Laser and Medical Technology GmbH, Berlin 12207 Berlin

Inventor: Roggan, Andre, Dr.rer.nat.

12163 Berlin Germer, Christoph-Thomas, Dr.med.

10711 Berlin Schädel, Daniela, Dipl.-Ing.

10249 Berlin Knappe, Verena, Dipl.-Ing.

10777 Berlin Müller, Gerhard, Prof.Dr.-Ing.

14129 Berlin

Date:

21.2.2000

Device for thermal treatment of biological tissue

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Task

The invention relates to an application device for the interstitial thermal sclerotherapy of biological tissue with the aid of high-power light radiation, whereby the tissue puncture and the light application can be carried out with one and the same device and the shaft of the application device is flowed through by a fluid.
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State of the art

The use of light (especially laser radiation) to generate high temperatures for tissue coagulation as a surgical procedure has long been known. In particular, the interstitial application of laser radiation is becoming increasingly important. The aim of the procedure is to achieve controlled and as homogeneous as possible heating of sufficiently large tissue volumes through the local absorption of the laser radiation. At temperatures above 45°C, depending on the exposure time, the denaturation of the tissue proteins leads to irreversible thermal cell damage, which leads to immediate or delayed death of the affected tissue areas. This makes it possible to treat tumors that would otherwise be inoperable. The denatured and dead tissue remains in the body (in situ) and is broken down or encapsulated by the body as scar tissue. Lasers in the near infrared wavelength range are usually used (preferably the Nd:YAG laser at 1064 nm), as the optical penetration depth is particularly great here.

In practice, special laser applicators or diffuser elements coupled with optical fibers are used

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vi.&ogr;

positioned within the diseased tissue. The laser applicators, such as those known from DE3813227, DE4041234, DE19739456 and WO96/07451, have a diffuse or directed emission of the laser light. This is achieved by mechanically or chemically roughening the end of the laser beam-guiding optical waveguide facing the object to be treated, or by directing the radiation into a scattering body connected to the end of the optical waveguide. The significantly larger emitting surface compared to the so-called bare fiber application prevents unwanted tissue overheating and associated carbonization. All known laser applicators have their sensitive mechanical structure in common, so that special catheter systems, also known as sheath catheters, usually have to be punctured into the diseased tissue, which ultimately accommodate the sensitive laser applicators. Such systems are described, for example, in DE4137983 and are characterized by the fact that the end of the beam-guiding optical waveguide facing the object to be treated is arranged in a tubular sheath catheter that is closed at the front and transparent to laser radiation, e.g. a plastic tube that is sealed air- and liquid-tight at the object-side end.

In addition to the optimal radiation characteristics, cooling the active applicator zone has proven to be extremely advantageous because it allows the maximum amount of energy that can be applied to be significantly increased without the risk of tissue carbonization. This means a significant increase in efficiency compared to the uncooled procedure, so that larger volumes of tissue can be treated. Cooling is achieved by flowing a suitable fluid around the active applicator zone. As described in US5569240, DE4403134 and

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As described in WO9426184, the fluid can be released directly into the body tissue. Better control can be achieved if the cooling fluid is led out of the body again via a coaxial or paraxial catheter channel according to the principle of the countercurrent method. Such working shafts or combinations of applicators and working shafts are known from DE4211526, DE4221354, DE4237286 and WO93/19680. The extension to include the complete magnetic resonance-compatible puncture set including puncture needle, guide wire, dilatation needle, introducer sheath and sheath catheter is described in DE19614780.
The systems described above are used to obliterate soft tissue tumors in various organs, particularly the liver, prostate and brain.
In the minimally invasive procedure that has been used up to now, the tumor is first punctured through the skin under local anesthesia and imaging control using X-ray computer tomography or magnetic resonance imaging. In a further step, the flexible catheter is then positioned in the puncture channel using a lock system and the actual laser applicator is then inserted.

The therapy is monitored using temperature-sensitive imaging techniques, preferably magnetic resonance imaging, as described in DE3 931854.
However, it has been found that the disadvantage of the described procedure is that in organs with a high blood supply, such as the liver or kidney, a large part of the applied energy is carried away by the bloodstream and is thus lost, so that, especially in the case of very large tumors, several synchronous 5 or asynchronous laser applications are often required.

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In addition, neighboring blood vessels can cause an asymmetry in the area of effect. Both of these factors increase the risk of tumor cells being transported and active tumor tissue being left behind.
5

Description

Surprisingly, it has been shown that the interstitial thermal treatment of body tissue with laser radiation can also be carried out in open surgery without any increased risk for the patient. The doctor gains access to the target organ in which the tumor is located via a skin incision. The application system is then positioned in the body tissue, preferably under ultrasound imaging control. But open magnetic resonance imaging is also becoming increasingly important, so that open surgical interventions, including laser sclerotherapy, can also be carried out under magnetic resonance control.

It has proven advantageous to partially or completely interrupt the supplying vessels of the organ, so that the blood flow in the target organ comes to a complete or partial standstill. The blood supply can remain interrupted or reduced for the entire time the laser is applied and is only restored after the application has ended or even after an additional waiting period. It was shown that this procedure increased efficiency by over 50% compared to the usual procedure, so that much larger tumors can be treated and the time saved shortens the operation time.

Surprisingly, a similarly good increase in efficiency could also be achieved when the 5 blood flow rate of the organ to be treated was reduced by the

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previous injection of perfusion-reducing substances into one of the supplying blood vessels is interrupted or reduced. The effect is based on the knowledge that the particles contained in the substances, preferably microscopic starch particles, cannot pass through the capillary system of the affected organ due to their diameter and therefore initially 'clog' it. The flow resistance increases considerably so that the overall blood flow to the organ decreases. In addition, the particles are designed in such a way that they dissolve after a while, thus ensuring normal blood flow to the organ again. In the case of the liver, there is also the possibility of selectively blocking certain capillary systems by optionally injecting the substance into the venous and/or arterial supplying vessels.

Another advantage of the open surgical procedure is the ability to locate small tumors that cannot be diagnosed using imaging techniques by manually palpating the organ and to also treat them. There are other advantages associated with the surgical procedure. Firstly, the range of indications can be expanded because the possibility of intraoperative tumor sclerotherapy means that patients can be transferred from an inoperable to an operable situation, so that, for example, a tumor that cannot be surgically removed is thermally sclerotherapy using laser radiation, while one or more tumors in the same organ are surgically removed at the same time. Secondly, tumors that are located so that minimally invasive access is not an option can be thermally sclerotherapy intraoperatively.

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However, the handling of the known catheter and laser application systems proved to be problematic in the open surgical procedure. In particular, the separate use of puncture needle, catheter and laser applicator, which were specially developed for the needs of a puncture under X-ray tomographic control and subsequent laser therapy under magnetic resonance imaging monitoring, turned out to be extremely disadvantageous. The disadvantages known to the specialist in practice are the following:

1. Especially during intraoperative procedures, several tumors often have to be cauterized or one or more of the tumors are so large that multiple punctures and laser therapy are necessary. The main problem with the known puncture and application systems is that the positioning of the entire system has to be carried out in several consecutive individual steps.

0 This procedure is extremely time-consuming and carries the risk of unnoticed applicator destruction.

2. The positioning of the known flexible catheter systems, especially in hard tumors, is often only possible after repeated widening of the puncture channel due to the short puncture path compared to the minimally invasive procedure, which requires an increased expenditure of time.

3. After positioning the flexible catheter system, the open surgical procedure 0 can cause it to bend in the area of the organ or tumor border, so that when the laser applicator is inserted it breaks unnoticed, which leads to an unpredictable distribution of energy in the tissue and ultimately to the destruction of the catheter. The catheter fuses with the

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the tissue and can only be removed from the tissue with a high risk of bleeding and mechanical force.

4. In the known systems, the laser applicator can only be inserted into the catheter once it has already assumed its final position in the body tissue. This means that the exact position of the laser applicator within the catheter cannot be visually checked; the only characteristic of the position of the applicator within the catheter is the mechanical stop of the applicator at the distally closed catheter end. However, this procedure is extremely error-prone because even a slight bend in the catheter (see 3.) can simulate such a stop, which then corresponds to an incorrect position of the laser applicator in the catheter and thus in the body tissue.

5. In the known catheter systems, the laser applicators are not fixed in their axial position in the catheter or are only fixed by a thin sealing lip. The intraoperative procedure can easily lead to an unnoticed displacement of the laser applicator in the catheter, so that the energy input in the area of the tumor tissue is not sufficient to completely obliterate it. The result is that the tumor progresses and the patient may have to undergo another operation.

6. The known catheter systems are only shown with very low contrast in the ultrasound imaging system, which is preferably used under open surgical conditions to control puncture and positioning, so that the exact position of the catheter tip cannot be reliably localized. However, knowledge of the position 5 of the catheter tip is of crucial importance.

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Significance for the complete destruction of the tumor. If treatment is inadequate, the tumor will progress and the patient will have to undergo another operation.

7. During the actual laser application, the therapy progress is monitored using ultrasound imaging during open surgery. In order to achieve a good coupling of the ultrasound head to the uneven organ surface, relatively high contact pressures are required, which can lead to distortion of the sheath catheter and breakage of the internal laser applicator. Here, too, there is a risk of uncontrolled energy release, resulting in catheter destruction and melting of the system to the tissue.

8. Furthermore, ultrasound imaging is an inadequate means of visualizing the success of therapy. Due to the high amounts of energy applied, temperatures of over 100 ⁰ C are reached in the tissue, so that the massive formation of interstitial vapor bubbles and the associated acoustic impedance jump mean that an assessment of the progress of therapy is only possible to a limited extent because the impedance jumps create so-called acoustic shadows.

The aim of the invention is therefore to develop an application device for the thermal sclerotherapy of 0 body tissue using high-power light radiation.

which enables both the puncture of the tissue and the application of light with only one device and thus avoids the disadvantages of the current state of the art in open surgical procedures.
35

This object is achieved according to the invention by an application device according to patent claims 1 to 22.

According to the invention, this application device consists of a pointed, rigid puncture shaft provided with a countercurrent flushing system with an internal diffuser element, as well as a handpiece coupled to the puncture shaft.

In contrast to the known solutions, the puncture shaft is made according to the invention in a composite construction comprising at least two different materials. This results from three requirements that must be combined, namely that the puncture shaft must have sufficient stability and rigidity for direct puncture of the tissue, that the puncture shaft must be transparent to the laser radiation in its distal area over the length of the diffuser element and that the puncture shaft must not break even under mechanical stress from bending forces. None of the materials used to date combines all three requirements, so that the solution according to the invention consists in the use of a rigid hollow cylinder that is transparent to the laser wavelength used and is coaxially surrounded by a stabilizing jacket over large areas. The distal end of the stabilizing jacket is preferably designed to taper so that the body tissue 0 can easily slide over its surface during the puncture. The length of the stabilization jacket is dimensioned so that the protruding part of the transparent hollow cylinder can completely accommodate the diffuser element and thus allow the free radiation of the laser power into the tissue.

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Surprisingly, it was found that such a composite structure could significantly increase the breaking strength compared to a single-component system without affecting the function.
In a preferred embodiment, the use of quartz glass or sapphire as a transparent hollow cylinder enables a four-fold improvement in the removal of excess heat from the tissue compared to existing systems. It was also recognized that the high melting point of glass significantly increases the thermal damage threshold, so that laser sclerotherapy can be carried out more safely. To enable the user to orientate himself and to ensure a reproducible position of the puncture shaft in the body tissue, the stabilization jacket is preferably provided with equidistant markings.

In another variant, which also combines the advantages mentioned above, the stabilizing jacket can also be arranged inside the transparent hollow cylinder.

In a continuation of the inventive concept, the stabilization jacket can also be guided movably over the transparent hollow cylinder in a third embodiment. This allows the stabilization jacket to be pushed completely or partially over the transparent hollow cylinder before the body tissue is punctured, thus ensuring optimal protection against mechanical damage. Immediately before the start of the laser sclerotherapy, the stabilization jacket is retracted to its starting position so that the laser radiation can radiate freely through the transparent hollow cylinder into the tissue. For safe use,

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Optional fixation of the stabilization sheath relative to the transparent hollow cylinder in defined positions, preferably in the retracted and advanced state. In addition to improved puncture, the movable stabilization sheath offers the possibility of avoiding the unintentional emission of high-energy laser power when the transparent part of the puncture shaft is only partially located in the body tissue during the treatment of marginal, smaller tumors.

An additional advantage of the movable stabilization sheath is that in the event of thermally induced adhesion of the body tissue to the transparent part of the puncture shaft, this adhesion can be easily released by pushing the stabilization sheath forwards, since according to the invention its end facing the body tissue has a very good shearing effect due to its conical inlet.

For atraumatic puncture of the body tissue, the puncture shaft is provided with a tip according to the invention, which is preferably realized by fusing the distal area of the transparent hollow cylinder. Optionally, after fusing, the tip is additionally ground to achieve a better puncture effect. Alternatively or in addition to this, a tapered element, preferably made of metal, ceramic or plastic, can be firmly connected to the distal end of the transparent hollow cylinder. It must be taken into account that the puncture of 0 body tissue is preferably monitored with ultrasound imaging, particularly under open surgical conditions. In an extended embodiment of the invention, the integration of a medium that appears with high contrast in the ultrasound image, ideally in the area of the puncture shaft tip, is therefore possible.

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Surprisingly, it was found that the integration of an air bubble into the puncture shaft tip leads to a significant signal due to the large acoustic impedance transition between the body tissue or puncture shaft material and the enclosed air bubble, which makes localization of the puncture shaft tip in the ultrasound image much easier. Optionally, a special ultrasound contrast medium can also be integrated into the puncture shaft tip. In an alternative embodiment, axially parallel air-filled capillaries are integrated into the transparent part of the puncture shaft, which also enable good localization due to the acoustic impedance jump.

An essential feature of the application device is the flow of a preferably biocompatible fluid through the puncture shaft. Due to the good heat conduction properties of the transparent hollow cylinder, in contrast to known systems, the fluid can be used at room temperature and no special measures are required to increase the heat capacity or lower the freezing point of the fluid 5. To achieve countercurrent cooling, the puncture shaft is designed with at least two lumens, preferably with a centrally guided, thin-walled tube that is transparent to the laser radiation, the outer diameter of which is smaller than the inner diameter of the hollow cylinder and the length of which is such that its distal end ends at least 1 mm before the distal closure of the puncture shaft. This allows the fluid to flow through the puncture shaft at a corresponding pressure difference, which can be achieved by an external pump system or a pump system coupled to the laser or a height difference between the storage vessel and the fluid outlet.

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can be achieved, flow in the centrally guided tube to the distal end of the puncture shaft and flow back in the free lumen between the tube and shaft. The task of the fluid is preferably to achieve a homogeneous temperature profile by targeted cooling of tissue areas close to the shaft.
In one variant, a scattering substance is added to the fluid in a known manner in order to improve the radiation properties of the diffuser element described below. In a special embodiment, the diffuser element can even be dispensed with entirely and the radiation emerging from the optical waveguide can be distributed homogeneously by the light-scattering substance dissolved in the fluid. In another variant, an ultrasound contrast agent is added to the fluid in order to facilitate the localization of the entire shaft through which the flow passes in the body tissue when using ultrasound imaging. In another embodiment, a magnetic resonance contrast agent is added to the fluid in order to facilitate localization when used in a preferably open magnetic resonance tomograph.

Another essential feature of the invention is the achievement of a homogeneous radiation of the laser light over a defined length of the puncture shaft. For this purpose, a diffuser element known in principle with a defined length between 0.5 cm and 10 cm is positioned centrally in the puncture shaft so that the entire length of the diffuser element lies in the area of the transparent hollow cylinder. Preferably, an optical waveguide is used as the diffuser element, the distal end of which can be used in a known manner over the length specified above as a volume diffuser or as a

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surface scatterer. In a preferred variant, the optical waveguide carrying the diffuser element is provided with a standardized adapter directly at its external end opposite the diffuser element in such a way that the optical waveguide can be connected directly to the laser device or to an optical element (e.g. beam splitter) connected upstream of the laser device.

The diffuser element and optical fiber are inserted into the centrally located tube of the shaft and fixed to the handpiece of the application device described below. The diameters of the diffuser element and optical fiber are dimensioned such that a sufficient lumen for the flow of the fluid remains between the inner diameter of the centrally located tube and the outer diameter of the optical fiber.

In another embodiment, the diffuser element and external optical waveguide are designed separately, so that there is no direct connection between the diffuser element and the laser or an optical element upstream of the laser. Instead, the diffuser element is firmly integrated into the puncture shaft together with a short, upstream optical waveguide. The laser radiation is fed into the upstream optical waveguide and thus into the diffuser element via a coupling point provided in the area of the handpiece described below using an external optical waveguide.

In order to ensure a force-fitting and form-fitting but detachable connection between the puncture shaft and the handpiece described below, the puncture shaft is provided with a 5 connector, preferably made of plastic or metal. The purpose of the connector

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Furthermore, the centrally located tube is guided and a suitable fluid flow is ensured within the puncture shaft and the handpiece described below in such a way that the fluid flow is connected to the free inner and outer lumens of the puncture shaft without leakage and pressure losses so that a defined flow direction is established.

According to the invention, the puncture shaft described above is coupled to a multifunctional handpiece in a permanent but detachable connection via the connector. The tasks of the handpiece include, in addition to ergonomic handling, the connection of all fluid supply and discharge hoses, expediently using the usual quick-closing systems according to the state of the art, and, in conjunction with the connector, the guarantee of a directed fluid flow within the handpiece and puncture shaft. A further task of the handpiece is to accommodate and fix the optical fiber supplying the laser light.

In the preferred variant of the diffuser element firmly connected to the external optical fiber, according to the invention an elastic seal with a central bore is provided at the optical fiber inlet opening of the handpiece, the central bore of which has a slightly larger diameter than the diffuser element and optical fiber. This ensures easy insertion of the optical fiber. By tightening a threaded union nut, the elastic seal is compressed in such a way that the optical fiber is fixed in a gas- and liquid-tight manner after the diffuser element has been correctly positioned in the shaft. In a continuation of the inventive idea,

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The external optical fiber can also be permanently fixed in the handpiece. This is preferably done using an adhesive connection so that the screw connection can be dispensed with.

In the variant with a separate diffuser element and external optical fiber, a suitable coupling element is provided on the handpiece. This serves on the one hand to permanently but detachably connect the external optical fiber to the handpiece and on the other hand to accommodate the short optical fiber section in front of the diffuser element.

A significant advantage of the separate structure of puncture shaft and handpiece is the easy exchangeability of the puncture shaft. In one variant, this can be disposed of as a single-use item after use, whereas the handpiece is subjected to the resterilization process. In addition, according to the invention, several shafts with diffuser elements of different lengths and/or different diameters can be realized and made available so that the shaft can be quickly changed during an operation, thus enabling optimal adaptation to the intraoperative situation.

In a special embodiment, the entire puncture shaft is provided with a close-fitting, distally closed, transparent sterile cover , preferably made of a temperature-stable and heat-conducting plastic, which is firmly connected to the shaft either by the choice of its diameter or by an additional fixation. The sterile cover can be removed and destroyed after the therapy 5 has been carried out, so that in the event of a

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Contamination with viruses or especially foreign proteins poses no risk to subsequent patients. The handpiece and puncture shaft themselves can be re-sterilized.

In a particular embodiment, it is necessary to prevent unintentional mechanical damage to the shaft or injury to the operating personnel during transport, sterilization and storage of the application device.

For this purpose, a stable protective cap is attached to the shaft or handpiece in a stable but detachable connection, preferably in the form of a bayonet lock, which completely accommodates the shaft in its interior. To make the interior easier to sterilize, the protective cap can optionally be provided with openings or slots.

Due to the insufficient informative value of intraoperatively used ultrasound devices for monitoring the current thermal damage state of the body tissue, a special feature of the invention is that in an extended embodiment, the point-by-point measurement of the tissue temperature at a defined radial distance from the diffuser element is possible. This parameter is of great importance for assessing the vital status of the cells, particularly in the edge area of a tumor to be sclerosed. For example, if a temperature of 60 ⁰ C is measured over a period of several seconds at the edge of the tissue volume to be sclerosed, taking into account a surgical safety margin 0 that may have to be maintained, 100% thermal sclerosing can be assumed at this point and the laser application can be terminated if the position simultaneously represents the largest extent of the tissue to be sclerosed.

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volume and an inhomogeneous temperature distribution can be neglected due to the interruption of blood perfusion described above. On the other hand, temperatures significantly below 60 ⁰ C are not sufficient to ensure complete sclerotherapy, so that in this case a continued laser application is indicated.

For the purpose of precise temperature measurement at defined positions within the body tissue, a special guide arm is attached to the application device in such a way that it runs at an angle of 90° to the puncture shaft axis. A fastening element is in turn mounted on the guide arm in a movable but fixable manner, which serves as a guide for targeted puncture with a temperature-sensitive probe through a long hole running parallel to the shaft axis. The guide arm is provided with equidistant markings so that the radial distance of the temperature probe from the shaft axis can be read and adjusted directly. The temperature-sensitive probe is advantageously also provided with markings or a mechanical stop so that the axial position of the probe can also be checked. In addition, the temperature-sensitive probe can advantageously be fixed in its guide hole using a screw clamp. In a simplified embodiment, several parallel holes can be arranged in the fastening element, or the guide arm 0 itself can have a number of equidistant guide holes, so that mechanical adjustment of the fastening element can be omitted.

In continuation of the inventive idea, the tissue temperature is not only displayed at selected locations in the tissue, but is actively used for online

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used to regulate the laser power. For this purpose, the measured temperatures are further processed either in the laser itself or in an additional electronic element and converted into a control signal in such a way that a defined temperature is reached or maintained at at least one of the measuring points.
In another variant, instead of temperature, the so-called autofluorescence of the tissue when excited in the wavelength range of 200 to 700 nm is used as a vital parameter for assessing complete thermal tissue obliteration. The increased or decreased appearance of certain fluorescence bands (e.g. NADH fluorescence) is a measure of the vital tissue condition and can be used to control or regulate the laser output power.

A special feature of the application device is that, in an advantageous embodiment, all materials and adhesives used for subcomponents and thus the entire system can be sterilized (eg gas sterilization, steam sterilization). This means that the application device or parts of the application device can be used several times.

A special feature of the application device is that in a special design variant the entire system is constructed from magnetic resonance compatible materials (e.g.

Titanium, ceramics, glass, plastics). This means that the application device can also be used in the new open magnetic resonance imaging systems, which allow working under open surgical conditions and, in contrast to ultrasound imaging, offer better

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Image quality and, above all, a better assessment of thermal sclerotherapy.

Advantageous developments of the invention are characterized in the subclaims and are described in more detail below together with the description of preferred embodiments of the invention with reference to the figures.

Fig.l a schematic representation of the application device in the body tissue, together with laser system, cooling circuit, ultrasound device and measuring probe,

Fig.2 shows a schematic section through the application device according to a preferred

Embodiment with a by fusing the

transparent hollow cylinder shaped

shaft tip,

Fig. 3 a schematic section through the puncture shaft with movable, external

Stabilization jacket,

Fig.4a,b a schematic section through the front area of the puncture shaft with an inserted shaft tip,

Fig.4c a schematic section through the front area of the puncture shaft with contrast, Fig.5a a schematic section through the fiber fixation in a variant with continuous optical fiber 0 Fig.5b a schematic section through the fiber fixation in a variant with air or liquid coupling

Fig.6 a schematic representation of the sterile cover Fig. 7 a schematic representation of the stable protective cap

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Fig. 8 a schematic representation of the guide arm for point measurement of temperature or fluorescence

Fig. 1 shows a schematic of a laser system 100 to which an optical waveguide 101 is connected via a suitable adapter 117. The optical waveguide is fixed to the handpiece 102 of the application device according to the invention. The puncture shaft 103 is positioned within the body tissue 104. To dissipate excess heat, a fluid flows through the puncture shaft in a countercurrent process, which fluid is initially located in a storage container 105, preferably a sterilely packaged infusion bag, and is conveyed to the application device via a hose 106 by a pump system 107, preferably a peristaltic pump. The fluid flows back via a further hose 108 into a collecting container 109. In a completely closed variant, the storage container 105 and the collecting container 109 can represent identical reservoirs. Typical flow rates for the fluid are in the range of 1 ml/min to 1000 ml/min. Furthermore, Fig. 1 shows an ultrasound scanner 110, which rests on the body tissue and is connected to the ultrasound device 111. The imaging ultrasound enables the optimal positioning of the puncture shaft 103 in the body tissue and also allows monitoring of the therapy. For precise determination of the tissue condition at selected positions within the body tissue 104, a measuring probe 112 is mounted on a guide arm 113 of the application device, which is connected to a measuring device 114. In an extended embodiment, the control or regulation of the laser power takes place via a

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Control system 115. Isotherms 116 are shown to illustrate the basic temperature profile in body tissue.

Fig. 2 shows the preferred embodiment of an application device for laser radiation according to the invention. The puncture shaft 103 is essentially formed from a transparent hollow cylinder 1, preferably made of quartz glass, which is firmly enclosed by a stabilization jacket 2, preferably made of metal. The two elements are preferably connected by adhesive, which contributes significantly to the stability and fracture resistance of the puncture shaft. The distal end 3 of the stabilization jacket is designed to be conical in order to avoid tissue trauma during insertion.

Transparent hollow cylinder 1 and stabilizing jacket 2 are expediently brought together in a connector 4 to establish the connection to the handpiece 102 and to ensure that no liquid can escape and that the puncture shaft can be quickly replaced. The diameter of the puncture shaft is typically in the range of 2 to 8 mm.

A thin-walled tube 5 runs centrally in the puncture shaft 103 and is transparent to the laser radiation used. The tube 5 ends approximately 1 mm before the tip 7 of the puncture shaft 103, so that a fluid 6 in the inner lumen of the tube 5 can reach the distal end of the puncture shaft 103 0 and flows back in the lumen between the tube 5 and the hollow cylinder 1. This ensures optimal cooling of the puncture shaft 103 according to the invention, particularly in the area in which the highest temperatures occur.

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The distal end of the puncture shaft 103 is formed by a tip 7, which enables the shaft to be easily inserted into the body tissue and is formed in a preferred variant by thermally fusing the transparent hollow cylinder 1. Typically, the length of the tip is 2-3 times the puncture shaft diameter. Figures 4a to 4c show further variants of the puncture shaft tip 7 and are explained separately.

The diffuser element 8 for distributing the laser radiation in the body tissue is basically known and is pushed centrally through the tube of the puncture shaft to the distal end. The laser light reaches the diffuser element via an optical fiber 9, which is firmly connected to the diffuser element 8 and merges into the external optical fiber 101 outside the application device. The transparent hollow cylinder 1 protrudes from the stabilization jacket 2 by at least the length of the diffuser element 8 in order to ensure the emission of the laser radiation. In a preferred embodiment, the stabilization jacket 2 is provided with equidistant markings 10 in order to ensure targeted and reproducible positioning in the body tissue.

The puncture shaft 103 is coupled to the handpiece 102 via its connector 4, preferably via a screw connection. This has two connectors 11 and 12 for the inlet and outlet of the fluid 6, preferably according to the known Luer-Lock principle. An internal distribution system 13 ensures that the fluid 6 flows through the puncture shaft 103 without leaks or pressure losses.

To fix the optical waveguide 9 or 101, a special clamping device is provided on the handpiece 102 at its 5 entry opening. In the preferred

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In this embodiment, an elastic sealing ring 14 with a central bore can be compressed by a threaded union nut 15 in such a way that the optical waveguide 101 is locked in the central bore in an air- and liquid-tight manner. The diameter of the opening is preferably approximately 2 mm and the opening of the union nut is designed to be tapered to enable the diffuser element to be easily inserted. This variant is particularly advantageous if the optical waveguide 101 is firmly provided with the diffuser element 8 at its distal end and with a standardized laser adapter (117) at its proximal end. Variants of this embodiment are shown in Figures 5a and 5b, which are explained separately.

Fig. 3 shows a special embodiment of the puncture shaft (103) in which the rigid stabilizing jacket 2 * is not firmly glued to the transparent hollow cylinder 1, but can be movably pushed over the transparent hollow cylinder. In a preferred variant, advance and retraction are carried out by rotating the stabilizing jacket 2 ^l , the axial movement being predetermined by a spiral groove 16 in the area of the connecting piece 4'. The stabilizing jacket is advantageously guided in the groove 16 using a fixing pin 17, which simultaneously ensures the fixing of the stabilizing jacket 2' in any desired position by rotating it.

0 Fig. 4a and 4b show two variants in which the distal end of the puncture shaft is formed by a conical 7' or flattened 7 ^%&lgr; tip made of plastic or metal, which is firmly connected to the transparent hollow cylinder 1.

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Fig. 4g shows a variant in which a special lumen 18 is incorporated into the tip 7, which accommodates a medium that is high-contrast in ultrasound imaging and thus facilitates the localization of the tip.

Fig. 5a shows an embodiment of the connection of

Optical fiber and handpiece, in which the optical fiber 9 or 101 is firmly connected to the diffuser element

(8) and the fixation in the handpiece 102

permanently by an adhesive connection 19. The

The optical fiber is protected from mechanical damage by a kink protection 23.

Fig. 5b shows an embodiment of the connection between the optical waveguide and the handpiece, in which only a short optical waveguide section 9 is directly connected to the diffuser element (8). The optical waveguide section 9 is firmly fixed in the handpiece 102, e.g. by an adhesive connection 20. The laser radiation from the external optical waveguide 101 is coupled in via a short air or liquid path 21, whereby the external fiber is expediently provided with an adapter 22 and anti-kink device 23 in such a way that it can be screwed to the handpiece 102. In order to keep the coupling losses low, the diameter of the external optical waveguide 101 is somewhat smaller than that of the internal optical waveguide 9.

Fig. 6 shows a sterile cover 24 which, in one embodiment, is pulled over the puncture shaft (103) before the puncture and is closed at its distal end. By choosing a suitable diameter or by a not shown

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For fixation, the sterile cover 24 is firmly connected to the puncture shaft (103). PTFE is preferably used as the material because it meets all requirements for transmission of the laser light, temperature stability and thermal conductivity. After laser sclerotherapy, the sterile protection 24 can be disposed of.

Fig. 7 shows a protective cap 25, preferably a cylinder made of metal or plastic, which can be attached to the application device especially for transport and storage. The attachment is preferably carried out on the handpiece (102) by providing the protective cap with a groove 31, which is pushed over one of the rinsing connections (11, 12). The oblique course of the groove 31 and a slight rotation of the protective cap can fix it to the handpiece (102). The protective cap has optional openings 26 to ensure reliable sterilization of the application device.

Fig. 8 shows a guide arm 113, which is preferably made of metal. A fastening element 27 is slidably mounted on the guide arm. In a preferred variant, the guide arm 113 has 5 equidistant markings 28 in order to lock the fastening element 27 at defined distances from the puncture shaft by means of a fixing screw 29. The fastening element 27 has one or more holes in order to accommodate a measuring probe 112 for temperature or fluorescence detection parallel to the axis of the puncture shaft. In a preferred embodiment, the guide arm 113 is fastened to the handpiece (102) by means of a clamping ring 30.

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Reference symbol

100 Laser system 101 external fiber optic cable 102 Handpiece of the application device 103 Puncture shaft of the application device 104 Body tissue 105 Storage container 106 supply hose 107 pump 108 return hose 109 Collection container 110 Ultrasound scanner 111 Ultrasound device 112 Measuring probe 113 Guide arm 114 Measuring device 115 Control system 116 isotherm 117 adapter 1 transparent hollow cylinder 2.2' rigid stabilization jacket 3 distal end of the stabilization sheath 4.4' Connector 5 Hose 6 Fluid 7.7' ,7'' tip 8th Diffuser element 9 internal optical fiber 10 Markings 11 Connection piece 12 Connection piece 13 Distribution system 14 Sealing ring «9« · · ? ? ?? ?? ?? · · ΦΦΦ* ΦΦΦΦΦ ?? ? ? *
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15 Union nut 16 spiral groove 17 Fixing pin 18 Ultrasonic marking 19 Adhesive bond 20 Adhesive bond 21 Coupling point 22 adapter 23 Anti-kink protection 24 Sterile cover 25 protective cap 26 opening 27 Fastener 28 Markings 29 Fixing screw 30 Clamp ring 31 Groove

Claims (25)

1. Device for the thermal sclerotherapy of biological tissue by means of light radiation according to the prior art, characterized in that the device essentially consists of two separable parts, a handpiece (102) and a dimensionally stable puncture shaft (103) with an optical window (1) and an internal diffuser element (8), which are locked but detachably connected by means of a force-fitting and/or form-fitting connection (4), so that the puncture shaft (103) can be replaced at any time. 2. Device according to claim 1, characterized in that the puncture shaft (103) is designed with at least two lumens, so that a fluid (6) flows through it according to the countercurrent principle for cooling and/or improving the radiation characteristics. 3. Device according to claim 2, characterized in that the transparent hollow cylinder (1) of the puncture shaft (103) is constructed from the material group comprising glasses, ceramics or plastics. 4. Device according to claim 3, characterized in that the transparent hollow cylinder (1) of the puncture shaft (103) is closed at a point by a thermal melting process (7). 5. Device according to claim 3, characterized in that the end of the transparent hollow cylinder (1) is closed by a pointed element (7', 7") made from the group of materials comprising metals, ceramics or plastics. 6. Device according to claim 4 or 5, characterized in that the rigid stabilizing casing (2, 2') of the puncture shaft is constructed from the material group comprising metals, ceramics or plastics and the end facing the transparent part tapers conically (3). 7. Device according to claim 6, characterized in that the rigid stabilizing casing (2, 2') is provided with equidistant markings (10). 8. Device according to claim 6 or 7, characterized in that the rigid stabilizing casing (2) is glued to the transparent hollow cylinder (1). 9. Device according to claim 6 or 7, characterized in that in one embodiment the rigid stabilizing casing (2') is pushed over the transparent hollow cylinder (1) and can be fixed in different positions. 10. Device according to claim 6 or 7, characterized in that in one embodiment the rigid stabilizing casing (2, 2') is mounted inside the transparent hollow cylinder (1). 11. Device according to one of the preceding claims, characterized in that the handpiece (102) has two connections (11, 12) for the inlet and outlet of the fluid (6) and a further opening for the optical waveguide (9, 101) supplying the laser radiation. 12. Device according to claim 11, characterized in that the optical fiber (9, 101) supplying the laser radiation is fixed to the handpiece (102) or puncture shaft (103) and the emerging laser radiation is coupled via a short air or fluid path (21) into the diffuser element (8) or an optical waveguide piece (9) arranged in front of the diffuser element. 13. Device according to claim 11, characterized in that the diffuser element (8) is firmly connected to the optical waveguide (9, 101) transmitting laser light and the diffuser element (8) and optical waveguide (9, 101) are advanced through an opening in the handpiece to the distal end of the puncture shaft (103). 14. Device according to claim 13, characterized in that the optical fiber (9, 101) carrying the diffuser element (8) is fixed to the handpiece (102) by a locking device (14, 15). 15. Device according to one of the preceding claims, characterized in that a distally closed, tightly fitting sterile cover (24) preferably made of temperature-stable, transparent and highly heat-conducting plastic is pulled over the entire puncture shaft (103). 16. Device according to claim 15, characterized in that the sterile cover (24) is destroyed after the therapy has been carried out. 17. Device according to one of the preceding claims, characterized in that in a special embodiment a variably adjustable guide (113) provided with equidistant markings (28) is fastened to the handpiece (102) or to the puncture shaft (103) in such a way that one or more measuring probes (112) can be positioned in or on the body tissue (104) parallel to the puncture shaft (103) at a defined radial and axial distance from the diffuser element (8). 18. Device according to claim 17, characterized in that the guide (113) together with the measuring probes (112) are locked but detachably connected to the handpiece (102) or the puncture shaft (103). 19. Device according to claim 17 or 18, characterized in that the temperatures or radial temperature profiles measured with the measuring probes (112) are used for power adjustment within the framework of an online control (114, 115) or for switching off the laser (100). 20. Device according to claim 17 or 18, characterized in that the autofluorescences or radial autofluorescence profiles measured with the measuring probes (112) are used for power adjustment within the framework of an on-line control (114, 115) or for switching off the laser (100). 21. Device according to one of the preceding claims, characterized in that for transport, storage and sterilization, a stable protective cap (25), the length of which extends beyond the puncture shaft length, is attached as protection against damage to the puncture shaft and as protection against injury. 22. Device according to one of the preceding claims, characterized in that all materials and adhesives used are sterilizable and thus reusable. 23. Device according to one of the preceding claims, characterized in that all materials used are compatible with magnetic resonance imaging. 24. Device according to one of the preceding claims, characterized in that a contrast agent is added to the fluid (6) which improves the representation of the puncture shaft (103) with an imaging method. 25. Device according to one of the preceding claims, characterized in that an air bubble (18) or a contrast agent (18) is enclosed preferably in the region of the tip (7) of the puncture shaft (103) to improve the ultrasound contrast.