Magnetic resonance - system with transcranial direct current stimulation and procedures

Abstract

The invention relates to a magnetic resonance imaging system comprising a device with a coil (7) with which a homogeneous magnetic field can be generated, a device with a coil (9) with which a high-frequency alternating magnetic field can be generated, with at least one antenna (1, 1a, 1b) for receiving an MR response signal, with an evaluation device which is set up in such a way that it can evaluate an MR response signal, with two electrodes (1, 1a, 1b, 13) and a control unit (4) which are set up in such a way that transcranial direct current stimulation can be carried out. The invention also relates to a method using such a magnetic resonance imaging system, wherein transcranial direct current stimulation (tDCS) and MRI or MRS are performed simultaneously. It can be used with a single modality. The invention therefore relates to an integrated multi-channel TDCS MRI system.

Description

[0001] The present invention relates to a magnetic resonance system with transcranial direct current stimulation and to a method.

[0002] A magnetic resonance system is set up in such a way that magnetic resonance spectroscopy or magnetic resonance spectroscopy can be carried out with it.

[0003] Tissues and organs can be visualized using magnetic resonance imaging. For example, cross-sectional images of a brain can be created. The term "functional magnetic resonance imaging" refers to a measurement method for locating and visualizing activated brain areas. Magnetic resonance imaging is also known by the abbreviation MRI. Another abbreviation is MRI. MRI stands for "magnetic resonance imaging." Instead of magnetic resonance imaging, the term nuclear magnetic resonance imaging is also used. Functional magnetic resonance imaging is abbreviated to fMRI.

[0004] In magnetic resonance imaging, signals can be measured, for example, from water molecules or hydrogen nuclei, which are subsequently referred to as MR response signals. However, signals can also originate from other nuclei, such as 13 C, 23 Well or 31 P. For example, tissue containing water molecules is placed in a strong, very homogeneous magnetic field. The tissue is exposed to electromagnetic waves in the radio wave range, which are radiated via a transmitting antenna for a short time, say a few microseconds. This excites the water molecules. The excitation causes a water molecule to absorb energy. The energy absorbed by a water molecule is released again after a short time in the form of electromagnetic waves in the RF spectrum, i.e., as MR response signals. The MR response signals are received by an antenna. Images can be calculated from the received MR response signals.

[0005] An antenna for receiving an MR response signal can be a coil. Multiple antennas, such as multiple coils, can be placed overlapping on the surface of a body. This ensures that a coil is always as close to the object as possible.

[0006] For three-dimensional spatial coding, the magnetic field can be briefly varied in different spatial directions using so-called gradient coils. This causes the resonant frequency of the water molecule to vary at different locations. Using computer calculations, these different frequency signals can be recalculated and combined to create an image of the object under investigation.

[0007] For example, MRI can be used to detect and localize pathological changes.

[0008] Magnetic resonance spectroscopy, also known by the abbreviation MRS, is based on nuclear magnetic resonance. Magnetic resonance spectroscopy makes it possible to identify and quantify chemical substances in tissue. Biochemical properties can be visualized, for example, to detect degenerated tissue. MRS enables the imaging of the metabolism of phospholipids and energy-rich phosphates in the living brain.

[0009] Magnetic resonance spectroscopy can also be combined with magnetic resonance imaging to detect, for example, malignant tissue with a high degree of probability.

[0010] In transcranial direct current stimulation (tDCS), a direct current is applied to the scalp via electrodes. This is intended to positively influence brain activity, for example, to alleviate symptoms of depression or improve athletic performance.

[0011] The present invention is intended to provide a magnetic resonance imaging system with improved properties. To achieve this object, a magnetic resonance imaging system can comprise the features of the first claim. The dependent claims relate to advantageous embodiments. The independent claim relates to a method enabled by the magnetic resonance imaging system.

[0012] A magnetic resonance system comprises a device with a magnet that can generate a strong, homogeneous magnetic field. The magnet can be a permanent magnet or an electromagnet. The magnet can be a superconducting magnet. The magnetic resonance system comprises a device with a coil that can generate a high-frequency alternating magnetic field. The magnetic resonance system comprises an antenna that can receive radio frequencies emitted by molecules, i.e., MR response signals. The antenna can be a coil. The magnetic resonance system comprises an evaluation device that is configured to evaluate MR response signals. The evaluation device can comprise a computer that processes received data during operation.The evaluation device can comprise an RF receiver interface, with which received MR response signals are electrically and / or electronically processed and / or conditioned. The RF receiver interface can comprise a preamplifier to amplify signals. The RF receiver interface can comprise electrical and / or electronic components to at least reduce interference during operation.

[0013] The magnetic resonance system can include one or more gradient coils. There is generally a gradient coil for each spatial direction. The magnetic resonance system includes a direct current stimulation device, which can be used to perform transcranial direct current stimulation. The direct current stimulation device comprises two electrodes and a control unit, which are configured to perform transcranial direct current stimulation. The evaluation device and control unit can, for example, share a computer. However, the evaluation device and control unit can each have their own computers.

[0014] A system within the meaning of the invention requires that at least one component provided for receiving MR response signals be at least physically connected to a component provided for performing transcranial direct current simulation. An MR system that is physically separated from a system for performing transcranial direct current simulation is not a system within the meaning of the present invention. The system makes it possible to perform magnetic resonance spectroscopy or magnetic resonance spectroscopy and transcranial direct current stimulation simultaneously. Magnetic resonance spectroscopy or magnetic resonance spectroscopy can be performed, for example, for diagnostic purposes. Transcranial direct current stimulation can be performed to stimulate brain activity or for therapeutic or other reasons.

[0015] An electrode for transcranial direct current stimulation can also serve as an antenna for receiving an MR response signal. This offers diagnostic and / or therapeutic advantages. It also reduces the number of parts that must be handled for an application.

[0016] The electrode for transcranial direct current stimulation, which also serves as an antenna for receiving an MR response signal, can be a coil or comprise a coil. A coil is a suitable design for receiving an MR response signal and for introducing a direct current into a body. It is therefore possible to integrate an electrode for performing transcranial direct current stimulation into a coil that can receive MR response signals.

[0017] The control unit for the transcranial direct current stimulation can be connected to the electrode for the transcranial direct current stimulation via a choke, which also serves as an antenna for receiving an MR response signal. The choke prevents an interfering MR response signal from reaching the control unit. Direct current can flow through the choke. Instead of a choke, another device can also be used to achieve this, such as a blocking circuit.

[0018] The evaluation device, which is configured to evaluate an MR response signal, can be connected via a capacitor to the electrode for transcranial direct current stimulation, which also serves as an antenna for receiving an MR response signal. For example, an RF receiver interface of the evaluation device can be connected to the electrode via a capacitor. This prevents any interfering direct current from flowing from the antenna to the evaluation device or the RF receiver interface.

[0019] The system comprises, in particular, at least three, at least four, at least five, or at least ten electrodes. The control unit can be configured to control which electrodes an electrical potential is applied to during the transcranial direct current simulation. The control unit can be configured to change the electrodes to which an electrical potential is applied during the transcranial direct current simulation. In this sense, multi-channel operation can be implemented.

[0020] The antenna for receiving an MR response signal can be part of a resonant circuit to enable better evaluation of the MR response signal. This can improve performance. In addition to the antenna, a capacitor or other capacitance can be provided. In addition to the antenna for receiving an MR response signal, an electrode for performing tDCS can be present to meet specific requirements. The electrode can be physically connected to the antenna.

[0021] The additional electrode can be connected to the antenna via a choke. The antenna can then also contribute to the introduction of a direct current into a body without fear of interfering MR response signals. Instead of a choke, a blocking circuit can be provided, through which a direct current can flow but through which an MR response signal cannot pass.

[0022] The invention also relates to a method using a magnetic resonance imaging system, wherein transcranial direct current stimulation (tDCS) and MRI or MRS are performed simultaneously.

[0023] Of particular importance is that the magnetic resonance imaging system can utilize MR response signals to improve the application of tDCS. For example, electrodes or antennas used as electrodes for tDCS can be selected by the system based on results obtained from MR response signals. Transcranial direct current stimulation can therefore be performed based on MR response signals to improve the application of transcranial direct current stimulation. The system can be configured and programmed to perform transcranial direct current stimulation based on MR response signals.

[0024] Electrodes can be selected for transcranial direct current stimulation based on MR response signals. The system can be configured to activate electrodes for transcranial direct current stimulation manually or automatically via an interface.

[0025] More than two electrodes can be involved in performing transcranial direct current stimulation. The system can be programmed accordingly, or electrodes can be manually selected via an interface.

[0026] The invention makes it possible to retrofit an existing magnetic resonance system without great technical effort so that a magnetic resonance system according to the invention is created.

[0027] Further advantages of the invention will become apparent from the embodiments described below.

[0028] They show: Fig. 1: Arrangement of coils of a magnetic resonance imaging system; Fig. 2: Arrangement of coils of a magnetic resonance imaging system; Fig. 3: Coil with RF receiver interface and control unit; Fig. 4: Components of a magnetic resonance system; Fig. 5: Flowchart; Fig. 6: Coil with resonant circuit, RF receiver interface and control unit; Fig. 7: Coil with electrode.

[0029] The Fig. 1 shows the arrangement of coils 1, 1a, 1b of a magnetic resonance imaging system, hereinafter referred to as antenna coils. The antenna coils 1 can be arranged on the head of a person and thus around a brain 2. The antenna coils 1 can be arranged overlappingly as shown. The antenna coils 1 can be connected to an RF receiver interface 3 of the magnetic resonance imaging system via connecting conductors. The RF receiver interface 3 can, for example, comprise an amplifier to amplify MR response signals.

[0030] The RF receiver interface 3 can comprise further or other electrical or electronic components for processing MR response signals. The RF receiver interface 3 can be connected to a computer that evaluates the data received by the RF receiver interface 3 during operation, for example, to generate images. Each antenna coil 1 can receive MR response signals. Each antenna coil 1 can serve as an electrode to perform transcranial direct current stimulation. A control unit 4 can apply an electrical voltage to two antenna coils 1a, 1b such that a direct current can flow from one antenna coil 1a to the other antenna coil 1b. The control unit 4 can be configured so that the two antenna coils 1a, 1b can be freely selected for performing tDCS.All coils 1, 1a, and 1b can always be available simultaneously to receive MR response signals. Antenna coil 1a then serves as the cathode. Antenna coil 1b then serves as the anode. The voltage can be selected so that brain 2 is stimulated by the flowing electrical current. Thus, transcranial direct current stimulation can be performed.

[0031] The control unit 4 can be configured so that more than two antenna coils 1a, 1b can be selected to perform transcranial direct current stimulation. An example is described in the Fig. 2. The antenna coils 1 are as shown in Fig. 1. The control unit 4 now uses three other antenna coils 1a for applying a first potential and another antenna coil 1b for applying a second potential, so that an electric current can flow from the antenna coils 1a to the antenna coil 1b. The voltage applied across the antenna coils 1a, 1b can be selected such that the brain 2 is stimulated by the flowing electric current.

[0032] It is also possible that all antenna coils 1 serve simultaneously as electrodes with which transcranial direct current stimulation is carried out.

[0033] The Fig. 3 shows an antenna coil 1, which can be electrically connected to the RF receiver interface 3 via capacitors 5. The capacitors 5 prevent an interfering direct current from flowing to the RF receiver interface 3. However, an MR response signal can pass through the capacitors 5 and thus be processed by the RF receiver interface 3. The antenna coil 1 can be electrically connected to the control unit 4 via a choke 6. A direct current can flow through the choke 6. The antenna coil 1 therefore does not impede transcranial direct current stimulation. However, the choke 6 prevents an interfering MR response signal from reaching the control unit 4.

[0034] The Fig. Figure 4 shows components of the magnetic resonance system. Magnet 7 is shown for generating a homogeneous magnetic field, which can form a tube into which a person's head 6 can be inserted. One or more gradient coils 8 can be present within the tube. Essentially, there is one gradient coil 8 for each spatial direction, thus a total of three gradient coils. A coil 9 within the tube can generate electromagnetic waves that can be used to excite molecules in the brain 2 or tissue. Antenna coils 1 can be mounted on the head of the person 6 to perform magnetic resonance examinations and transcranial direct current stimulation at the same time.

[0035] Through the Fig. Figure 5 illustrates how the magnetic resonance system can be used over time t. It is shown that, on the one hand, MRS and fMRI can be performed alternately, for example. On the other hand, tDCS can be performed simultaneously with MRS and fMRI, which is indicated by a "+". The "-" sign means that tDCS, i.e. transcranial direct current stimulation, is not performed during this period. Thus, MRS or fMRI can be performed without tDCS being performed in parallel. It is also possible to perform only tDCS, although this is rare in practice because MRS and fMRI are usually particularly time-consuming examinations. Furthermore, special advantages can only be achieved through the combination of received MR response signals and tDCS.Over the course of time t, tDCS can be performed with repeatedly changing antenna coils 1a and / or 1b, for example, in order to react to evaluated MR response signals. The number of antenna coils 1a and / or 1b involved in performing tDCS can also be changed over time, for example depending on evaluated MR response signals. Thus, for example, stimulation can initially only be carried out on the right side of a brain 2 by one antenna coil 1a and one antenna coil 1b, and subsequently on a right and a left side by two antenna coils 1a and one antenna coil 1b. Finally, all coils can be involved in performing tDCS, whereby only one antenna coil 1b can serve as the anode and all other antenna coils 1a as the cathode. However, it can also be the other way around, that only one antenna coil 1a is connected as cathode and more than one antenna coil 1b is connected as anode.It is also possible that more than one antenna coil 1a is connected as a cathode and at the same time more than one antenna coil 1b is connected as a cathode.

[0036] The magnetic resonance system can also perform sequences other than MRS or FfMRI, such as DWI (diffusion imaging), SWI (susceptibility-weighted imaging), or PWI (perfusion imaging). It is also possible to calibrate and perform tDCS simultaneously. The magnetic resonance system can also perform T1-weighted or T2-weighted imaging and, if necessary, tDCS.

[0037] The Fig. 6 is similar to that in the Fig. 3, but additionally includes a resonant circuit capacitor 12 to enable improved evaluation of an MR response signal. Coil 1 and capacitor 12, referred to here as the resonant circuit capacitor, then form an electrical resonant circuit. The ends of the antenna coil 1 can be connected to a choke 11 to achieve improvements. This can be particularly advantageous if there is also an additional electrode 13. Choke 11 and resonant circuit capacitor 12 can be connected in parallel. The capacitors 5 can be arranged as shown in the Fig. 6 shown connected to the resonant circuit.

[0038] The Fig.Figure 7 illustrates that, for example, the interior of the antenna coil 1 can be used to change the design of an electrode if necessary. An electrode 13 of any shape can be present within the antenna coil 1, into which a direct current can be introduced via a coupling point 14. The antenna coil 1 can be electrically connected to the coupling point 14 via a choke 6. The coupling point 14 can be connected to the control unit 4 via an electrical conductor. A potential can be applied to the coupling point 14 via the control unit 4. Two electrical conductors can also connect the control unit 4 to the coupling point 14. One electrical conductor can be used to apply a positive potential. The other electrical conductor can be used to apply a negative potential.

Claims

[1] Magnetic resonance imaging system comprising a device with a magnet (7) with which a homogeneous magnetic field can be generated, a device with a coil (9) with which a high-frequency alternating magnetic field can be generated, with at least one antenna (1, 1a, 1b) for receiving an MR response signal, with an evaluation device which is set up in such a way that it can evaluate an MR response signal, with two electrodes (1, 1a, 1b, 13) and a control unit (4) which are set up in such a way that a transcranial direct current stimulation can be carried out. [2] Magnetic resonance imaging system according to the preceding claim, characterized by that an electrode for transcranial direct current stimulation is at the same time an antenna (1, 1a, 1b) for receiving an MR response signal. [3] Magnetic resonance imaging system according to the preceding claim, characterized bythat the electrode for transcranial direct current stimulation, which is also an antenna for receiving an MR response signal, is a coil (1, 1a, 1b, 13) or comprises a coil (1, 1a, 1b, 13). [4] Magnetic resonance imaging system according to one of the two preceding claims, characterized by that the control unit (4) of the transcranial direct current stimulation is connected via an RF choke (6) to the electrode (1, 1a, 1b) for the transcranial direct current stimulation, which is also an antenna (1, 1a, 1b) for receiving an MR response signal. [5] Magnetic resonance imaging system according to one of the three preceding claims, characterized bythat an RF receiver interface is present which is set up in such a way that it can process an MR response signal, and the RF receiver interface is connected via a capacitance (5) to the electrode (1, 1a, 1b) for the transcranial direct current stimulation, which is also an antenna (1, 1a, 1b) for receiving an MR response signal, so that no direct current can flow from the antenna (1, 1a, 1b) to the RF receiver interface (3). [6] Magnetic resonance imaging system according to one of the preceding claims, characterized by that the antenna (1, 1a, 1b) for receiving an MR response signal is part of an oscillating circuit (11, 12). [7] Magnetic resonance imaging system according to one of the preceding claims, characterized by that at least three electrodes are available for performing transcranial direct current simulation. [8] Magnetic resonance imaging system according to one of the preceding claims, characterized bythat in addition to the antenna (1, 1a, 1b) for receiving an MR response signal, an electrode (13) for performing TDCS is provided. [9] Magnetic resonance imaging system according to the preceding claim, characterized by that the electrode (13) is connected to the antenna (1, 1a, 1b) via an RF choke (6). [10] Magnetic resonance imaging system according to one of the preceding claims, characterized by that it is set up in such a way that transcranial direct current stimulation (tDCS) is carried out during operation depending on MR response signals. [11] Magnetic resonance imaging system according to one of the preceding claims, characterized by that it is arranged in such a way that, during operation, electrodes (1a, 1b) for carrying out transcranial direct current stimulation (tDCS) are selected as a function of MR response signals. [12] Magnetic resonance imaging system according to one of the preceding claims, characterized by that it is set up in such a way that more than two electrodes (1a, 1b) are involved in the implementation of tDCS during operation. [13] Method with a magnetic resonance imaging system according to one of the preceding claims, characterized by that transcranial direct current stimulation (tDCS) and MRI or MRS are performed simultaneously.

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