METHOD AND APPARATUS FOR TRANSBODY MAGNETIC STIMULATION AND/OR INHIBITION

TECHNICAL FIELD OF THE INVENTION

The invention relates to an apparatus and a method for transbody, in particular transcranial, magnetic stimulation and/or inhibition by inducing magnetic fields, especially a focalized or diffused three dimensional (3D in the following) gradient magnetic field in a certain area of the human or animal body and specifically of the human brain. The invention also relates to a magnetic resonance imaging (MRI in the following) apparatus and method, a computer program and a data storage medium.

The invention also relates to different advantageous uses of such transbody magnetic field stimulation and/or inhibition, in particular for localizing and mapping particular functions of biological tissue for example by stimulation or inhibition of brain areas, for evaluating the concentration of molecules or drugs in specific areas of the human body and for delivering magnetic field sensitive particles or drugs to a particular area in the human body.

BACKGROUND OF THE INVENTION

To explore the function of the human brain, a method usually called "transcranial magnetic stimulation" (commonly abbreviated as TMS) has been developed, which is nowadays performed routinely by hand-hold single coils in the shape the figure 8 or figure 0. By stimulating (in the sense of activating) and/or inhibiting certain areas of the brain, information can be obtained which is of high importance in a wide variety of medical fields, such as for example neuro-surgery, neurology and psychiatry.

It has turned out that by applying local magnetic fields of suitable strength (e.g. in the order of 0.5 Tesla) and frequency (e.g. in the order of 0.5 - 20 Hz), certain areas of the brain can not only be stimulated, but can also be temporarily blocked, so that activity of those areas is inhibited.

Stimulating and/or inhibiting allows for example to determine, which function a certain area of the brain has. Such information is useful e.g. when planning a tumor resection in the brain. It is of vital importance that during such surgery as little damage as possible is done to the non-affected areas of the brain. In order to find a way of carrying out a brain surgery, which is the least harmful to the brain, medical image giving techniques as in particular magnetic resonance imaging, hereinafter referred to as MRI, together with techniques such as TMS, are used. Different techniques for performing TMS are described for example in US 6,572,528.

EP 1 269 913 A1 describes a method for transcranial magnetic stimulation and inhibition, which advantageously allows to check in advance, which effect an actual resection of a certain spot of the brain would have.

Known systems for carrying out such stimulation and inhibition can comprise so called "neuronavigation software", which allows to visualize the theoretical convergent field point of the applied magnetic stimulation/inhibition field in a magnetic resonance image (hereinafter called "MR-image"), which has prior to TMS been taken of a patient.

According to the method described in EP 1 269 913 A1 , first a MR-image of the brain of a patient to be examined is taken. Based on this image, a simulation model of the surface of the brain is generated, which is important as the sensorial, motor, visual, auditory and olfactory functions of the patient are being controlled by areas on the surface of the brain. A stimulation device, such as for example a coil for generating a local magnetic field, is then arranged relative to the surface of the head of the patient, such that the magnetic field generated by the coil is focused on the surface of an area of the brain, said area being in practice determined on said model. Thus, certain areas of the brain are stimulated or inhibited and the reaction of the patient upon this stimulation/inhibition is measured in a suitable way, which depends on the type of reaction to be measured. For example, if the visual cortex is examined, a patient receiving stimulation signals induced by TMS is to state in which area of the field of vision the stimulation signal generates a flash or which area of the field of vision can no longer be perceived due to an inhibiting signal. This allows mapping of the visual cortex, i.e. to assign the fields of vision of the eyes to individual structures on the visual cortex. If certain motor functions are to be measured, sensors on the skin of the patient may be used to measure muscular activity.

However, the exact position in the brain, where stimulation or inhibition took place, is not measured according to this known method. Based on the simulation model and several assumptions on the magnetic properties of the skull and the brain of the patient it is only estimated that operating the stimulation device in a certain position and with certain parameters would generate a magnetic field in a certain spot of the brain.

The known techniques have several disadvantages. For example, the anatomical MR- image acquisition leads to diffraction/distortion errors so that the theoretical point of the magnetic stimulation as planned might not correspond exactly to the effective location of stimulation and it is not possible to realize this error, which is estimated to be in the order of about 5 mm. Also, the co-registration between the magnetic stimulation device and the patient's head has normally at least a 1.5 mm minimal error and is often around 10mm in clinical routine, due to the approximation error of the head position.

A proposal to resolve this last point is to have an MRI compatible coil marked with MRI-visible fiducials in order to know exactly where the coil is on the head surface based on morphological images and then to extrapolate the location of the field convergent point within the brain. Coils in the shape of an 8 or a 0 are the most common devices for such purpose and are in fact the only ones used in clinical routine, while other magnetic stimulator devices exist, especially devices with multiple coils. Other systems propose multi-channel (or multi coil) stimulation devices somehow arranged in a helmet.

To allow the individual creation of a local magnetic field, DE 199 14 762 A1 describes a coil arrangement comprising a plurality of individual coils for TMS fixed on a helmet-like structure. As each TMS-coil is individually controllable, it is possible to trigger a magnetic stimulation at various locations in the brain of a patient by means of corresponding activation of the individual coils. In addition, the helmet-like structure also provides a radio-frequency head antenna for use in so called "functional magnetic resonance imaging" (commonly abbreviated as "fMRI"). Position markers are allocated to each individual coil, each of said markers comprising a substance that is detectable by magnetic resonance imaging. Thus, the coil arrangement described in DE 199 14 762 A1 allows that an MR-image is taken, in which the position of the coils for

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transcranial magnetic stimulation is shown, thus linking the position of the TMS-coils to the brain.

Whereas according to EP 1 269 913 A1 , first an MR-image is taken to create a model of the brain, on which afterwards TMS is performed to determine, which areas of the model correspond to which functions of the brain, the coil arrangement described in DE 199 14 762 A1 allows that a magnetic resonance image and even a functional magnetic resonance image is taken while the coils for TMS are already in a fixed position relative to the head of the patient, but only while no current is flowing through said coil. However, again the location of the field created by the TMS-coils is not measured but determined only theoretically based on assumptions of the magnetic properties of the brain and the skull of the patient. Thus, even if this technique partilally solves the problem of the co-registration error, it does not solve the problem of the diffraction/distortion error of the MRI anatomical acquisition, of the diffraction/distortion error of the magnetic field used for the stimulation and of the error due to movements of the head of the patient.

As some functions of the brain are located on a rather small area of the brain, even small deviations in localizing those functions gender dramatic localization errors. It would therefore be advantageous to be able to determine the exact location of the magnetic field created in the brain during TMS.

Clinicians and researchers are very much concerned about the different step errors. To evaluate the imprecision of the systems, it has been tried to perform brain explorations several minutes after stimulation. The most commonly used brain exploration tools are

Positron Emission Tomography (PET) and functional MRI, both of which allowing only an indirect appreciation of the brain activity since they can only record blood oxygenation and vessel dilatation, which are supposed to be modified with delay after a neuronal activity.

In an article by PAUS, Tomas et al. entitled "Transcranial Magnetic Stimulation during Positron Emission Tomography: A new Method for Studying Connectivity of the Human Cerebral Cortex", The Journal of Neuro-Science, May 1 , 1997, Vol. 17, No. 9, pp. 3178-3187, a method is disclosed that enables mapping of neuronal connections in the brain. By means of TMS, a neural activity is triggered at a limited location of the brain

surface whose function is known. To do so, a small conventional coil with a figure- eight-conductor configuration is placed near the location of interest - for example somewhat above the skull in the region of the frontal eye area - and a sequence of short magnetic pulses with a magnitude of approximately 1 ,5 Tesla is applied by feeding current pulses into the coil. Subsequently, the neuronal response of the brain is acquired using PET with delay and low spatial resolution (15mm). If the location of simulation is the region of the frontal eye area, the response to this stimulation is acquired at the primary visual cortex using PET. In this way, findings concerning the spatial and temporary interconnectedness of brain functions (the so-called "connectivity") can be obtained.

However, the described specific TMS coil arrangement must be positioned at the desired location. If the stimulation location is to be modified, this requires a new positioning of the TMS coil arrangement. Moreover, since the field distribution of the magnetic field is predetermined by the geometry of the coil, additional TMS coil arrangements must be provided if stimulation with other field profiles is to take place.

Besides TMS, several methods of localizing certain functional areas of the brain are known, for example fMRI, during which a patient has to perform in an MRI apparatus certain activities, which enhances blood flow in the areas of the brain assigned to these activities. Due to the decoupling of blood flow and oxygen consumption during neuronal activity, this change in blood flow in particular areas of the brain can be measured, since this causes hyperoxygenation and thus a drop in the concentration of paramagnetic deoxyhemoglobin. This effect, known as the "BOLD effect", can be measured by magnetic resonance imaging. However, the method is relatively imprecise since it indirectly records neuronal activity and only provides a spatial resolution in the range of about 0.2 - 0.5 cm with a poor time resolution of 3-5 s. Keeping in mind that certain functions are located on a rather small area of the brain, such spatial resolution is not satisfactory.

To summarize, up-to-date the only method allowing exact determination of the location of a certain function on the surface of the brain is an invasive method known as "direct cortical stimulation" (commonly abbreviated as "DCS"). This method requires a skull opening and is then performed on the exposed cranium by means of electrodes. An electrode is introduced into a particular area of the brain and an electrical impulse is

applied, which causes a certain reaction of the patient, for example perception of visual impressions or contraction of muscles. Due to the high risk, DCS is only performed in pathological cases, whereas for numerous applications it would be highly useful to know the exact location of certain functionalities in the brain without opening the skull.

SUMMARY OF THE INVENTION

It is an object of the invention to overcome the disadvantages of the prior art discussed above, in particular disadvantages like field heterogeneity errors, MRI acquisition diffraction/distortion errors, diffraction phenomena due to MRI rooms having insufficient magnetic shielding, magnetic stimulation field diffraction/distortion errors, co-registration errors, targeting errors, head movement errors, indirect representation of brain reaction (poor blood flow spatial resolution) and delay control (poor temporal resolution) of brain reaction.

It is a particular object of the invention to provide a method and an apparatus for transcranial magnetic stimulation and inhibition allowing determining of the exact location in the brain, in which a stimulating or inhibiting magnetic field was actually created with a high spatial resolution (preferably less than 1 mm) and a high temporal resolution (preferably less than 0.05 sec) and with no step errors.

It is a further object of the invention to provide a method and an apparatus for non-invasively identifying, which particular area of a brain fulfils a certain function.

A further object of the invention is to provide a method and an apparatus for magnetic stimulation in any place of the human body, and in concomitant multiple loci.

To solve these problems, the invention proposes first a method for transbody, in particular transcranial, magnetic stimulation and/or inhibition in a certain area of a body, in particular a certain area of a brain, by generating temporarily at least one first magnetic field in at least one area of the body, in particular of the brain, said first magnetic field being locally restricted, wherein said first magnetic field is created within a second magnetic field, said second magnetic field being a constant magnetic field, in particular the constant magnetic field B ₀ of a magnetic resonance imaging apparatus.

The advantage of temporarily creating said first magnetic field within a constant field is that once the first field stops, an electronic spin relaxation occurs, which can be recorded by an RF-antenna just as "normal" relaxation images

In particular, the invention proposes to create said first magnetic field for a certain period of time (which, depending on the purpose of the field, can be very short, like 0.05 seconds) and that immediately after this period a magnetic resonance image of the relaxation signals produced by the tissue of said at least one area of the body, in particular of said brain, is taken. This allows for the first time to exactly locate the area, in which the magnetic field was indeed created, by actually measuring signals created by the tissue after switching off the locally restricted magnetic field, whereas in the prior art this location is only mathematically determined based on assumptions of the magnetic properties of the brain and the skull, which may in practice vary from patient to patient. Thus, the accuracy of the targeting can be controlled and any diffusion, diffraction and co-registration errors can be corrected.

The first magnetic field can be an undulating field having a frequency of about 0.1 to 100 MHz.

Preferably, the first magnetic field is a gradient magnetic field, preferably having a three dimensional gradual variation in terms of frequency and/or intensity. A gradient magnetic field is a field in which frequency, orientation and/or intensity change(s) across the Cartesian space.

The gradient field is performed most of the time at a supra clinical level to induce a physiological tissue reaction, while regular MRI always stays infra clinical, so that no tissue function is affected.

The technical advantage of creating a gradient stimulation is that relaxation recording can be performed and coded in the Cartesian space. There are no relaxation images if there is no constant field. Actual brain or body stimulation is performed without such constant magnetic field, so that nothing can be recorded just after the stimulation.

The least one locally restricted magnetic field may be repeated depending on the effect which shall be achieved (i.e. inhibition or stimulation), for example with a repetition

frequency of about 0.1 to 100 Hz, and preferably of 0.5 to 20 Hz. It has turned out that by applying such local magnetic fields of suitable strength - e.g. in the order of 0.5

Tesla higher than the strength of the constant magnetic field Bo - and of suitable frequency - e.g. in the order of 0.5 to 20 Hz - certain areas of the brain can not only be stimulated, but can also temporarily be blocked, so that activity of those areas is inhibited.

Preferably, said at least one first magnetic field may consist in an undulated magnetic stimulation with specific frequencies (fjMs) chosen on the basis of the frequency of the precession movement of a certain type of atoms or molecules of interest in said second magnetic field, allowing obtaining relaxation signals of said atoms or molecules of interest. Such fjMS could be equal to or a multiple or submultiples of the usual frequencies of the MRI-RF-Antenna excitation, which are f= fo ± f, fo being the frequency of the precession movement fo = (y Bo) / 2 π (κ=gyromagnetic ratio, Bo=constant magnetic field) of molecules of interest (proteins, neurotransmitters, drugs, etc...) to obtain relaxation signals of the molecules or of the atom of interest ( ¹ H=42.57MHz, ³¹ P=17.24MHz, ¹³ C=IOJOMHz, ²³ Na=I 1.26MHz ₁ etc..) to obtain relaxation signals of the desired atom.

The method of the invention can also be used to concentrate magnetic field sensible particles in said at least one area, in which the first magnetic field is generated, an may be performed such that an activating energy is generated in said at least one area, in particular by directing and concentrating electromagnetic or ultrasonic waves in said area in order to activate or increase various activities of said particles (biochemical activity, thrombosis activity, thermal activity, ionisation activity, photonic activity, acoustic activity etc.).

The invention also proposes a method for non-invasively identifying, which particular area of a brain fulfils a certain function, comprising the steps of: a) creating at least one locally restricted magnetic field within the constant magnetic field of a magnetic resonance imaging apparatus, b) determining the location of the creation of said at least one locally restricted magnetic field in said brain by magnetic resonance imaging,

c) determining, which function is performed by the area of the brain, in which said at least one locally restricted magnetic was created.

The invention furthermore concerns an apparatus for transbody, in particular transcranial, magnetic stimulation and/or inhibition in a certain area of a body, in particular a certain area of a brain, comprising means for creating temporarily at least one first magnetic field in at least one area of the body, in particular of the brain, said first magnetic field being a locally restricted field, said apparatus further comprising means for generating a second magnetic field such that said first magnetic field is created within said second magnetic field, said second magnetic field being a constant magnetic field, in particular the constant magnetic field Bo of a magnetic resonance imaging apparatus.

Preferably, said apparatus comprises means, in particular a magnetic resonance imaging apparatus, for recording a relaxation signal produced in said area after the temporary generation of said at least one first magnetic field.

Preferably, the means for generating at least one first magnetic field are designed such that said first magnetic field is a gradient magnetic field, preferably with a three dimensional gradual variation in terms of frequency, orientation and/or intensity.

The invention also proposes a magnetic resonance imaging method for imaging at least one area of a human or animal body comprising the steps of temporarily stimulating the at least one area of a human or animal body with a first magnetic field and recording at least one relaxation signal after, preferably immediately after canceling said first magnetic field, wherein said first magnetic field is generated within an independent constant magnetic field.

To carry out such method, the invention proposes a magnetic resonance imaging apparatus for imaging at least one area of a human or animal body comprising first magnetic field generation means for temporarily stimulating the at least one area of a human or animal body, second magnetic field generation means for generating an

independent constant magnetic field, wherein at least one magnetic field generated by the first magnetic field generation means is within said independent constant magnetic field, and relaxation signal recording means.

Further details and advantages of the invention will become evident from the following description of preferred embodiments in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram showing a principle idea of the invention.

Fig. 2 is a schematic diagram showing different modes of carrying out the invention.

Fig. 3 is a schematic drawing of an apparatus for carrying out the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Fig. 1 schematically visualizes a basic idea of the invention: first, a locally restricted magnetic gradient field, hereinafter simply referred to as "gTMS pulse", is generated for a certain period of time in a certain area of a body, for example an area in the human brain. In the style of the above mentioned abbreviation "TMS", "gTMS" is an abbreviation for gradient transbody magnetic stimulation. As mentioned, depending on the strength of the magnetic field, the field cannot only stimulate but also inhibit tissue functions. In the following, unless explicitly mentioned otherwise, gTMS stands for both, stimulation and inhibition.

After creation of said gTMS pulse, which may, as indicated exemplarily in Fig. 1 , have a duration of 1 msec, with the aid of known signal recording means the T1 and T2 relaxation signals are acquired, T1 and T2 being well known in the art of MRI.

Alternatively, just before, during or immediately after said gTMS pulse a magnetic gradient field of high frequency as commonly used in MRI can be applied to said area,

said gradient field having the same excitation geographical parameters as said at least one locally restricted magnetic field. This enhances the relaxation signals that could be obtained from said area and allows even more precise location of the actual area in which the magnetic field indeed was created.

As an option, said gTMS can be performed such that more than one magnetic field is generated at the same time in different areas of the body, said magnetic fields having optionally the same or different characteristics in said different areas. For example, different areas in the brain can be activated while others are inhibited, which is very informative in studying neuronal networks.

The method according to the invention can be carried out such that a) at least one first magnetic field for a restricted period of time with a first intensity in an area of the body is created, b) the location of the creation of said at least one first magnetic field in said area by magnetic resonance imaging is determined, c) said determined location of creation with the location of a preselected area in said body is compared, d) if said determined location and said location of said preselected area do not match, said at least one first magnetic field is created in a different location for a restricted period of time with said first intensity and the steps b) to d) are repeated until said determined location and said location of said preselected area do match, e) said at least one first magnetic field is created in the location of said preselected area with a second intensity, wherein said second intensity is higher than said first intensity.

The preselected area can be selected on the basis of a magnetic resonance image.

Advantageously, the invention allows that if the generation of said first magnetic field in said area shows an undesired effect, another first magnetic field is generated in said area having a reversing effect. For example, if stimulation of a certain area in the human brain shows an undesired effect like an epileptic seizure, in inhibiting magnetic field can be created in said area.

Fig. 2 shows different modes of carrying out the method according to the invention. In the figures, "ct" stands for clinical threshold and marks the line indicating the intensity of the gTMS pulse, above which tissue function is affected.

Fig. 2a shows a mode of carrying out the method, which can be called a "safety mode". As indicated in Fig. 2a, gTMS pulses are generated with an intensity below said clinical threshold. This allows to visualize the exact area where the magnetic field was created via the recorded relaxation signals. To enhance the signal/noise ratio, the gTMS pulses and the acquisition of the T1/T2 signals are carried out in a repetitive fashion.

For the brain, the intensity of the gTMS pulse can be set inferior to 90% of resting motor threshold. This safety mode avoids inutile supraclinical effective stimulation, reduces the epileptic risk and increases the safety of the system.

Once the parameters are set correct, said first magnetic field can be generated with a second intensity being higher than the first intensity to affect the tissue function in said area. This can be done in a "single shot mode" (shown in Fig. 2b) consisting in one stimulating/inhibiting pulse within the predefined desired area and/or in a repetitive mode (shown in Figs. 2c and 2d) consisting in a train of repetitive pulses within the predefined desired area. For the brain, such single shot transcranial magnetic stimulation can activate neuronal activity informative for brain mapping. In the repetitive mode, the magnetic field can comprise a train of repetitive pulses within said area with a frequency preferably between 0.1 and 100 Hz to affect the tissue function. Said pulses may have a duration between 0 and 1 seconds, preferably between 0.03 and

0.15 seconds. Fig. 2c shows a "repetitive slow mode", in which gTMS pulses are repeated with a frequency between about 0.5 and 2 Hz, Fig. 2d shows a "repetitive fast mode", in which gTMS pulses are repeated with a frequency between about 2 and 20 Hz.

The first magnetic field may also be generated for a time of several minutes up to several hours within said area (schematically shown in Fig. 2e), which allows to deliver and accumulate magnetic field sensible particles (drugs, nanoparticles, liposomes etc.) in a desired area of the body. The magnetic field can be static or oscillatory in its orientation, which may increase diffusion of the particles. An additional focused

magnetic field or a radiofrequency or an ultrasonic signal can activate said particles (e.g. by heating them up) in order to generate their biological activity in the desired area.

Fig. 3 schematically shows a MRI apparatus for imaging at least one area of a human or animal body comprising means for generating the independent constant magnetic field (commonly referred to as "Bo field"), which are integrated in the so called "MRI-doughnut". As usual, the MRI apparatus further comprises relaxation signal recording means comprising in particular an MRI-RF-antenna for picking up T1 and T2 relaxation signals.

According to the invention the apparatus has also magnetic field generation means for temporarily generating within said constant magnetic field Bo a locally restricted magnetic field, namely the gTMS pulse mentioned above, wherein the term "pulse" is not meant to indicate only a short period of time. As mentioned above, the magnetic field can be used to accumulate particles and can thus last rather long.

In this embodiment, the means for creating said gTMS pulse are provided in form of several coils (magnetic field generators) arranged in a three-dimensional structure, which can be placed close to the body of a patient to be examined. In this particular embodiment, the magnetic field generators are arranged in a helmet like structure, in which also the MRI-RF-antenna is integrated.

To give an idea of the arrangement, Fig. 3 also shows schematically the head of a patient to be examined, resting on an MRI-bed.

With such apparatus, a magnetic resonance imaging method for imaging at least one area of a human or animal body can be performed by temporarily stimulating the at least one area of a human or animal body with a first magnetic field within said constant magnetic field and recording at least one relaxation signal after, preferably immediately after canceling said first magnetic field.

The gTMS coils are advantageously designed to facilitate generation of said first magnetic field in a repetitive fashion comprising a train of repetitive pulses within said

area to affect the tissue function, and are in particular designed to allow creating said at least one locally restricted magnetic field with at least a first intensity and a second intensity, said second intensity being higher than said first intensity.

In a preferred embodiment, the gTMS coils are designed to facilitate generation of a magnetic field which causes in said area a radio frequency excitation like a usual magnetic resonance imaging radio frequency antenna and/or a gradient magnetic field like a usual magnetic resonance imaging gradient field of a magnetic resonance imaging gradient coils antenna.

The apparatus according to the invention advantageously can comprise numerous means for automatically controlling certain functions of the apparatus, such as means for automatically determining the location of the generation of said at least one first magnetic field in said area based on magnetic resonance imaging, - means for automatically comparing said determined location of the generation of said at least one first magnetic field with a preselected area in said body, means for automatically repositioning the location of the generation of said at least one first magnetic field based on the comparison with said preselected area analysis means for automatically determining the exact location, in which the first magnetic field was generated based on data obtained by said relaxation signal recording means at a first time T1 and at a second time T2.

With such means, it could be automatically checked, if the chosen parameters for operating the means for creating the locally restricted magnetic field were correct or need to be adapted.

The apparatus may have a control unit with a neuronavigation software stored thereon and a program to control the multiple magnetic field generators.

The apparatus can be used for non-invasively identifying, which particular area of a brain fulfils a certain function, if it further comprises means for sensing functional reactions upon stimulation or inhibition of said brain by said at least one locally restricted magnetic field.

The apparatus can also be used to record a relaxation signal in a spectroscopic sequence fashion for collecting spectroscopic data of biological components, especially concentrations of molecules or drugs and optionally their variation within said area.

Furthermore, the apparatus can be used for preplanning neurosurgery.

The apparatus can also be used for accumulating magnetic field sensible particles, preferably drugs, nanoparticles, and/or liposomes in a desired area of the body.

COMMERCIAL APPLICABILITY

The methods and the apparatus described herein can be commercially used in a wide variety of non-therapeutic treatments and examinations of the human body, for example in commercially testing and developing new drugs and brain stimulating devices. However, the methods and apparatus disclosed herein can also be used for magnetic drug targeting and accumulating magnetizable drugs in certain areas of the body, for example the brain, for treating certain malfunctions of the brain by stimulating or inhibiting certain brain areas and other therapeutic purposes. These uses are implicit part of the invention and will, upon entry into the national phase of this PCT application, be claimed in those countries, whose national law provides for corresponding claims.