Broadband Wireless System for Multi-Modal Imaging

Abstract

The multi-modal imaging system, in particular for brain imaging, comprising a pump signal generator which emits at least one pump signal in the radio frequency (RF)-range with a first power P1 and a second power P2, a wireless detection unit, which comprises at least one parametric resonator circuit with multiple resonance modes, wherein the at least one parametric resonator circuit comprises at least two varactors, at least one capacitor and at least one inductance, wherein, in a first detection mode, the pump signal, having a first power P1, induces a first pump current in the at least one parametric resonator circuit, wherein the at least one parametric resonator circuit is operated below its oscillation threshold and generates a first output signal by amplifying a first input signal, which is provided due to a magnetic-resonance (MR) measurement, wherein an external receiving device receives the first output signal, wherein, in a second detection mode, the pump signal, having a second power P2, induces a second pump current in the at least one parametric resonator circuit, wherein the at least one parametric resonator circuit is operated above its oscillation threshold and generates a second output signal, wherein the second output signal is modulated with a second input signal, wherein the second input signal is provided by at least one neuronal probe device, connected to the at least one parametric resonator circuit, wherein the external receiving device receives the second output signal.

Claims

1. System (1) for imaging, in particular for brain imaging, comprising a pump signal generator (2) which emits at least one pump signal (3, 3a, 3b) in the radio frequency (RF)-range with a first power P1 and a second power P2, a wireless detection unit (4), which comprises at least one parametric resonator circuit (5) with multiple resonance modes, wherein the at least one parametric resonator circuit (5) comprises at least two varactors (6, 7) at least one capacitor (8) and at least one inductance (9), wherein, in a first detection mode, the pump signal (3, 3a), having a first power P1, induces a first pump current (10) in the at least one parametric resonator circuit (5), wherein the at least one parametric resonator circuit (5) is operated below its oscillation threshold and generates a first output signal (11) by amplifying a first input signal (13), which is provided due to a magnetic-resonance (MR) measurement, wherein an external receiving device (17) receives the first output signal (11), wherein, in a second detection mode, the pump signal (3, 3b), having a second power P2, induces a second pump current (12) in the at least one parametric resonator circuit (5), wherein the at least one parametric resonator circuit (5) is operated above its oscillation threshold and generates a second output signal (14), wherein the second output signal (14) is modulated with a second input signal (15), wherein the second input signal (15) is provided by at least one neuronal probe device (16), connected to the at least one parametric resonator circuit (5), wherein the external receiving device (17) receives the second output signal (14).

2. The system (1) according to claim 1, characterized in that the first input signal (13) has a first frequency ω1, wherein the parametric resonator circuit (5) resonates at the first frequency ω1 and generates a first input current (18), wherein the pump signal (3, 3a) has a third frequency ω3, wherein the parametric resonator circuit (5) resonates at the third frequency ω3 and generates the first pump current (10) or the second pump current (12), depending on the first power P1 and a second power P2, wherein the varactor (6, 7) generates a resulting current (19), based on the first input current (18) and the first pump current (10), wherein the parametric resonator circuit (5) resonates at a second frequency ω2, in response to the resulting current (19) to generate the first output signal (11).

3. The system (1) according to one of the claim 1 or 2, characterized in that the second frequency ω2 is nearly equal to the first frequency ω1, wherein the second frequency ω2 differs from the first frequency ω1 by a difference frequency ωd, which is in the range between 10 kHz to 100 kHz, preferably between 20 kHz to 80 kHz, more preferably between 40 kHz to 80 kHz, wherein the third frequency ω3 is essentially twice the first frequency ω1.

4. The system (1) according to one of the previous claims, characterized in that the system (19) comprises a device for image processing (20), wherein the external receiving device (20) transmits the first (11) and/or the second output signal (12) to the device for image processing (20).

5. The system (1) according to one of the previous claims, characterized in that, wherein the at least one parametric resonator circuit (5) is a parallel circuit comprising two varactors (6, 7) and one capacitor (8) in the center leg (21) of the parallel circuit, wherein the cathode of the first varactor (6) is connected with the first terminal of the capacitor (8) and the cathode of the second varactor (7) by a first connection, wherein the anode of the first varactor (6) is connected with the second terminal of the capacitor (8) and the anode of the second varactor (7) by a second connection, wherein the first and the second connection form a first (9a) and a second inductance (9b), wherein the at least one parametric resonator circuit (5) is a wire loop by which the two varactors (6, 7) are connected and with a center leg (21) in which the capacitor (8) is arranged.

6. The system (1) according to claim 5, characterized in that the at least one neuronal probe device (16) is connected to the first terminal of the capacitor (8) in the center leg (21) of the parallel circuit, wherein the second terminal of the capacitor (8) in the center leg of the parallel circuit is connected to a ground electrode (22).

7. The system (1) according to one of the previous claims, characterized in that the at least one parametric resonator circuit (5) is integrated in a planar thin film element, wherein the thin film element consists of a polyimide.

8. The system (1) according to one of the previous claims, characterized in that the wireless detection unit (4) comprises at least two parametric resonator circuits (5, 5a, 5b), wherein the at least two parametric resonator circuits (5, 5a, 5b) overlap spatially, wherein no electrical connection exists between the at least two parametric resonator circuits (5, 5a, 5b), wherein each parametric resonator circuit (5, 5a, 5b) is tuned to resonate at a different third frequency ω3a, ω3b, such that, by applying a pump signal (3, 3a, 3b) with the third frequency ω3a, ω3b, one parametric resonator circuit (5, 5a, 5b) can be activated.

9. The system (1) according to one of the previous claims, characterized in that the wireless detection unit comprises four parametric resonator circuits (5, 5a, 5b, 5c, 5d), which are arranged in a quadrilateral, wherein each resonator circuit (5, 5a, 5b, 5c, 5d) overlaps spatially with at least one adjacent resonator circuit (5, 5a, 5b, 5c, 5d), wherein each parametric resonator circuit (5, 5a, 5b, 5c, 5d) is tuned to resonate at a different third frequency ω3a, ω3b, ω3c, ω3d, such that, by applying a pump signal (3, 3a, 3b) with a third frequency ω3a, ω3b, ω3c, ω3d, one parametric resonator circuit (5, 5a, 5b, 5c, 5d) can be activated.

10. The system (1) according to one of the claim 8 or 9, characterized in that the parametric resonator circuits (5, 5a, 5b, 5c, 5d) are sequentially or simultaneously activatable, wherein, for a simultaneous activation of at least two parametric resonator circuits (5, 5a, 5b, 5c, 5d), at least two different pump signals (3, 3a, 3b) with a third frequency ω3a, ω3b, ω3c, ω3d, are used at the same time.

11. The wireless detection unit according to claim 11, characterized in that the first input signal (13) has a first frequency ω1, wherein the parametric resonator circuit (5) resonates at the first frequency ω1 and generates a first input current (18), wherein the pump signal (3, 3a) has a third frequency ω3, wherein the parametric resonator circuit (5) resonates at the third frequency ω3 and generates the first pump current (10) or the second pump current (12), depending on the first power P1 and a second power P2, wherein the varactor (6, 7) generates a resulting current (19), based on the first input current (18) and the first pump current (10), wherein the parametric resonator circuit (5) resonates at a second frequency ω2, in response to the resulting current (19) to generate the first output signal (11), wherein the second frequency ω2 is nearly equal to the first frequency ω1, wherein the second frequency ω2 differs from the first frequency ω1 by a difference frequency ωd, which is in the range between 10 kHz to 100 kHz, preferably between 20 kHz to 80 kHz, more preferably between 40 kHz to 80 kHz, wherein the third frequency ω3 is essentially twice the first frequency ω1.

12. The wireless detection unit according to claim 11 or 12, characterized in that, wherein the at least one parametric resonator circuit (5) is a parallel circuit comprising two varactors (6, 7) and one capacitor (8) in the center leg (21) of the parallel circuit, wherein the cathode of the first varactor (6) is connected with the first terminal of the capacitor (8) and the cathode of the second varactor (7) by a first connection, wherein the anode of the first varactor (6) is connected with the second terminal of the capacitor (8) and the anode of the second varactor (7) by a second connection, wherein the first and the second connection form a first (9a) and a second inductance (9b), wherein the at least one parametric resonator circuit (5) is a wire loop by which the two varactors (6, 7) are connected, and with a center leg (21) in which the capacitor (8) is arranged, wherein the at least one neuronal probe device (16) is connected to the first terminal of the capacitor (8) in the center leg (21) of the parallel circuit, wherein the second terminal of the capacitor (8) in the center leg of the parallel circuit is connected to a ground electrode (22).

13. The wireless detection unit according to one of the claims 11 to 13, characterized in that the wireless detection unit (4) comprises at least two parametric resonator circuits (5, 5a, 5b), wherein the at least two parametric resonator circuits (5, 5a, 5b) overlap spatially, wherein no electrical connection exists between the at least two parametric resonator circuits (5, 5a, 5b), wherein each parametric resonator circuit (5, 5a, 5b) is tuned to resonate at a different third frequency ω3a, ω3b, such that, by applying a pump signal (3, 3a, 3b) with a third frequency ω3a ω3b, one parametric resonator circuit (5, 5a, 5b) can be activated.

14. The wireless detection unit according to one of the claims 11 to 14, characterized in that the parametric resonator circuits (5, 5a, 5b, 5c, 5d) are sequentially or simultaneously activatable, wherein, for a simultaneous activation of at least two parametric resonator circuits (5, 5a, 5b, 5c, 5d), at least two different pump signals (3, 3a, 3b) with a third frequency ω3a, ω3b, ω3c, ω3d, are used at the same time.

Description

[0047] In the drawings:

[0048] FIG. 1 shows a system for imaging, in particular for brain imaging;

[0049] FIG. 2 shows a wireless detection unit according to one embodiment;

[0050] FIG. 3 shows a wireless detection unit according to one embodiment;

[0051] FIG. 4a, b show a wireless detection unit according to one embodiment;

[0052] FIG. 5a, b, c show a wireless detection unit according to one embodiment.

[0053] FIG. 1 shows a system 1 for imaging, in particular for brain imaging, comprising a pump signal generator 2 which emits a pump signal 3, 3a, 3b in the radio frequency (RF)-range with a first power P1 and a second power P2, a wireless detection unit 4, which comprises at least one parametric resonator circuit 5 with multiple resonance modes, wherein the at least one parametric resonator circuit 5 comprises at least two varactors 6, 7, at least one capacitor 8 and at least one inductance 9, wherein, in a first detection mode, the pump signal 3, 3a, having a first power P1, induces a first pump current 10 in the at least one parametric resonator circuit 5, wherein the at least one parametric resonator circuit 5 is operated below its oscillation threshold and generates a first output signal 11 by amplifying a first input signal 13, which is provided due to a magnetic-resonance (MR) measurement, wherein an external receiving device 17 receives the first output signal 11, wherein, in a second detection mode, the pump signal 3, 3b, having a second power P2, induces a second pump current 12 in the at least one parametric resonator circuit 5, wherein the at least one parametric resonator circuit 5 is operated above its oscillation threshold and generates a second output signal 14, wherein the second output signal 14 is modulated with a second input signal 15, wherein the second input signal 15 is provided by at least one neuronal probe device 16, connected to the at least one parametric resonator circuit 5, wherein the external receiving device 17 receives the second output signal 4.

[0054] The system comprises an MRI scanner device 23 that enables the visualization of organs, organ function, and/or other tissue within a body, in particular a brain of a subject 24. The subject may be an animal, such as a rat, a monkey or a human. The MRI scanner device 23 comprises a primary magnet 25 that generates a uniform magnetic field B0 that is applied across the body of the subject 24 under observation. The magnetic field B0 is preferably in the range of between approx. 3 T to approx. 21 T, more preferably in the range of between approx. 7 T to approx. 14 T. The subject is arranged in a bore. In case of animal studies, the bore has a bore diameter of preferably in the range of between 50 cm to 6 cm, more preferably 12 cm.

[0055] The MRI scanner device 23 further comprises at least one smaller gradient magnet 26 which generates a gradient magnetic field BG. The magnetic field B0 aligns the nuclear spins, in particular of the hydrogen atoms, in the tissue. The nuclear magnetic spins precess with the so-called Larmour frequency about the magnetic field direction like gyroscopes. Due to the additional gradient magnetic field BG, the Larmour frequency is altered along the gradient magnetic field BG. Thus, the gradient magnet allows image “slices” of the body to be created.

[0056] The MRI scanner device 23 further comprises an RF-signal generator 27, which applies a radio frequency (RF)-pulse BRF, perpendicular to said magnetic field B0 of the primary magnet. This RF-pulse causes the nuclear spins to tilt away from the alignment direction. In the absence of the RF-pulse BRF, the nuclear spins relax to the lower energy state and align with the magnetic field B0. The surplus energy gained by the RF-pulse is emitted by a RF-signal. This signal is the first input signal of the wireless detection unit 4.

[0057] The system 1 comprises a device for image processing 20. The external receiving device 17 transmits the first 11 and the second output signal 14 to the device for image processing 20. The external receiving device 17 comprises a receiving coil, which detects the first 11 and the second output signal 14 inductively. The system 1 may further comprise a user interface 28 which comprises an input device, such as a keyboard, and/or an output device, such as a display.

[0058] The pump signal generator (2) may also be able to emit more than one pump signals (3, 3a, 3b) with a first power P1 and a second power P2 simultaneously.

[0059] Embodiments of the wireless detection unit 4 are shown in the FIGS. 2 to 5. The wireless detection unit 4 for use in a magnetic-resonance (MR) measurement comprises at least one parametric resonator circuit 5 with multiple resonance modes, wherein the at least one parametric resonator circuit 5 comprises at least two varactors 6,7, at least one capacitor 8 and at least one inductance 9, wherein, in a first detection mode, a pump signal 3, 3a, having a first power P1, induces a first pump current 10 in the at least one parametric resonator circuit 5, wherein the at least one parametric resonator circuit 5 is operated below its oscillation threshold and generates a first output signal 11 by amplifying a first input signal 13, which is provided due to a magnetic-resonance (MR) measurement, wherein, in a second detection mode, the pump signal 3, 3b, having a second power P2, induces a second pump current 12 in the at least one parametric resonator circuit 5, wherein the at least one parametric resonator circuit 5 is operated above its oscillation threshold and generates a second output signal 14, wherein the second output signal 14 is modulated with a second input signal 15, wherein the second input 15 signal is provided by a neuronal probe device 16, connected to the at least one parametric resonator circuit 5.

[0060] The at least one parametric resonator circuit 5 is a parallel circuit comprising two varactors 6, 7 and one capacitor 8 in the center leg 21 of the parallel circuit. The cathode of the first varactor 6 is connected with the first terminal of the capacitor 8 and the cathode of the second varactor 7 by a first connection. The anode of the first varactor 6 is connected with the second terminal of the capacitor 8 and the anode of the second varactor 7 by a second connection. The first and the second connection form a first 9a and a second inductance 9b. Thus, the parametric resonator circuit 5 is a LC-circuit with multiple resonance modes. The at least one parametric resonator circuit is a wire loop by which the two varactors 6, 7 are connected, and with a center leg 21 in which the capacitor 8 is arranged. The wire loop has a diameter in the range of between 5 mm to 15 mm, preferably 9 mm. For a 9 mm loop, a capacitor 8 with a capacity of 7.5 pF may be chosen. The capacitor 8 may be in the form of a chip capacitor.

[0061] The wireless detector 4 in FIG. 2 may be used for MRI measurements. The use of such a device has the advantage that no additional power source in the form of a battery is required. Further, the transmission of the measured signal does not require the use of a cable.

[0062] The device shown in FIG. 3 has the additional advantage that next to the input signals 11, stemming from the MRI-measurement, signals 15 stemming from at least one neuronal probe device 16 may be transmitted wirelessly by the same detection unit 4. The detection mode is switchable, just by applying different powers P1 and P2 of the pump signal 3, 3a, 3b. A first pump signal 3, 3a, having the first power P1, would be applied for the first detection mode, in which the first input signal 11 is detected and transmitted to the external receiving device 17. A second pump signal 3, 3b, having the second power P2, would be applied for the second detection mode, in which the second input signal 15 is detected and transmitted to the external receiving device 17.

[0063] The at least one neuronal probe device 16 is connected to the first terminal of the capacitor 8 in the center leg 21 of the parallel circuit, wherein the second terminal of the capacitor 8 in the center leg of the parallel circuit is connected to a ground electrode 22. Alternatively, the neuronal probe device 16 could be connected to the first and the second terminal of the capacitor 8.

[0064] The neuronal probe device may preferably comprise at least one EEG-probe, which detects the differences of electrical potentials due to brain activity.

[0065] In the first detection mode, the power P1 of the first pump signal 3, 3a does not provide enough gain to compensate for the resonator loss. Thus, the parametric resonator circuit is operated in the amplifier mode. Parametric oscillation occurs when the parametric amplification compensates the loss of a resonator at the resonance frequency. Thus, the parametric resonator circuit is operated in the oscillator mode. This is the case in the second detection mode, when the power P2 of the second pump signal 3, 3b does provide enough gain to compensate for the resonator loss.

[0066] The first 3, 3a and the second pump signal 3, 3b have a third frequency ω3, wherein the parametric resonator circuit 5 resonates at the third frequency ω3 and generates the first pump current 10 or the second pump current 12, depending on the first power P1 and a second power P2. In the first resonance mode, the parametric resonator circuit 5 is tuned to match the pump signal. Thus, when the parametric resonator circuit 5 is operated below the oscillation threshold, the pump signal 3a, which serves as power source, has a power P1 and the third frequency ω3.

[0067] The first input signal 11 has a first frequency ω1, wherein the parametric resonator circuit 5 resonates at the first frequency ω1 and generates a first input current 18. Thus, in the second resonance mode, the parametric resonator circuit 5 is tuned to match a first input signal, which is provided due to a magnetic-resonance (MR) measurement. The varactor 6, 7 generates a resulting current 19, based on the first input current 18 and the first pump current 10. The varactor 6,7 has a high Q zero biased condition and performs frequency mixing. Thus, the resulting current 19 is generated by mixing the first input current 18 and the first pump current 10. The parametric resonator circuit 5 resonates at a second frequency ω2, in response to the resulting current 19, to generate the first output signal 11. The first output signal, also called “idler signal”, preferably has the frequency ω2=ω3−ω1 or ω2=ω3+ω1. It is preferred that the first output signal/the corresponding resulting current 19 mixes again with the pump signal at ω3/the corresponding pump current 10. In doing so, a secondary resulting current 19a and a corresponding secondary first output signal 11a with a frequency ω4 are generated. The frequency ω4 is essentially equal to the first frequency ω1: ω4=|ω3−ω2|=|ω3−(ω3±ω1)|=|ω1|. Thus, an amplified signal 11a with the frequency ω1 may be generated and emitted by the parametric resonator circuit 5.

[0068] Preferably, the second frequency ω2 is nearly equal to the first frequency ω1, wherein the second frequency ω2 differs from the first frequency ω1 by a difference frequency ωd, which is in the range between 5 kHz to 100 kHz, preferably between 20 kHz to 80 kHz, more preferably between 40 kHz to 80 kHz. Preferably, the difference frequency ωd is larger than the receiver bandwidth of the MRI-system. The MRI-signal is typically frequency-encoded by a spatially varying gradient field. This gradient slightly alters the precession frequencies of the nuclear spins. The bandwidth of the gradient field is typically in the range between 5 kHz to 100 kHz, preferably 50 kHz. Advantageously, the difference frequency ωd is about 5 kHz to 20 kHz larger than the imaging bandwidth. Preferably, the difference frequency ωd is about 10 kHz larger than the imaging bandwidth. Thus, given a typical bandwidth of 50 kHz, the difference frequency ωd would preferably be 60 kHz. The advantage of such a design is that the frequencies ω1 and ω2 may conveniently be differentiated.

[0069] Advantageously, the third frequency ω3 is essentially twice the first frequency ω1. By making the idler frequency ω2 close enough to the Larmour frequency ω1, and making ω3 approximately twice ω1, it is possible for ω1 and ω2 to share a single circuit mode. Preferably, the parametric resonator circuit 5 is then a double frequency resonator. The pumping frequency is preferably in the range between 1 GHz to 1.2 GHz. The frequencies ω1, ω2 would therefore be in the range between 500 MHz to 600 MHz.

[0070] In another embodiment shown in FIGS. 4a, 4b, the parametric resonator circuit 5 can support anti-symmetric current flow 29 and symmetric current flow 30. The anti-symmetric mode 29, which corresponds to FIG. 4a, can be tuned to the Larmour frequency ω1 by the two varactor diodes on the left and right arches; it can create a dipole field pattern that is sensitive to the first input signal 13, in the form of a MRI signal. The symmetric mode 30, which corresponds to FIG. 4b, can be tuned by a tunable capacitor 8 in the center leg; it can create a butterfly field pattern that is sensitive to the external pump signal at ω3. The parametric resonator circuit 5 may also be connected to a neuronal probe device 16.

[0071] In the second detection mode, the parametric resonator (oscillator) circuit 5 oscillates at the frequency ωc, which is half the frequency of the pump signal ω3. For example, ωc is 600 MHz. Naturally, the output signal 14 would then have a carrier frequency ωc of 600 MHz. Due to the second input signal 15 provided by the neuronal probe, the sidebands of the oscillation peak of the second output signal are modulated. The amplitude of sidebands will change linearly with the strength of the neuronal signal.

[0072] Preferably, such a modulation is a modulation of the amplitude of the second output signal and/or the frequency of the second output signal. Advantageously, the second input signal is encoded as sidebands of the oscillation peak of the second output signal. The frequency of the signal from the neuronal probe device 16 is within +/−1 kHz from the carrier frequency ωc.

[0073] Although, during MRI detection, the MR signal intensity is slightly modulated by EEG signal, this modulation will not affect the results of most MR experiments. Furthermore, this intensity modulation may be removed from the output signal 11 by comparing multi-band signals generated by the parametric resonator circuit. During EEG detection, the contribution of MRI signals on the oscillation signal is negligible.

[0074] The at least one parametric resonator may be embedded in a planar thin film element. Preferably, the thin film element consists of a polyimide, more preferably of a copper-clad polyimide. The at least one parametric amplifier circuit in the form of a wire loop, by which the two varactors are connected, and with a center leg in which the capacitor is arranged, is laminated by the polyimide or another suitable material. Advantageously, such a thin film element has a diameter in the range between 2 to 20 mm, preferably between 5 to 15 mm, more preferably between 8 to 12 mm. Advantageously, such a thin film element has a thickness in the range between 1 to 6 mm, preferably between 2 to 4 mm.

[0075] The wireless detection unit 4 may comprise at least two parametric resonator circuits 5, 5a, 5b. The at least two parametric resonator circuits 5, 5a, 5b overlap spatially and no electrical connection exists between the at least two parametric resonator circuits 5, 5a, 5b. Hereby, each parametric resonator circuit 5, 5a, 5b is tuned to resonate at a different third frequency ω3a, ω3b, such that, by applying a pump signal 3, 3a, 3b with the third frequency ω3a, ω3b, one parametric resonator circuit 5, 5a, 5b can be activated.

[0076] In FIGS. 5a, 5b and 5c, an embodiment is shown, in which the wireless detection unit comprises four parametric resonator circuits 5, 5a, 5b, 5c, 5d, which are arranged in a quadrilateral. For simplicity reasons, the actual components, like the two varactors and the capacitor in the center leg, are not shown in the FIGS. 5a, 5b and 5d. Each resonator circuit 5, 5a, 5b, 5c, 5d overlaps spatially with two adjacent resonator circuits 5, 5a, 5b, 5c, 5d. Each parametric resonator circuit 5, 5a, 5b, 5c, 5d is tuned to resonate at a different third frequency ω3a, ω3b, ω3c, ω3d, such that, by applying a pump signal 3, 3a, 3b with a third frequency ω3a, ω3b, ω3c, ω3d, one parametric resonator circuit 5, 5a, 5b, 5c, 5d can be activated. It is conceivable that only one of the parametric resonator circuits 5, 5a, 5b, 5c, 5d is connected with a neuronal probe device according to FIG. 3. The other three parametric resonator circuits 5, 5a, 5b, 5c, 5d would then have no such connection and would be embodiments according to FIG. 2. It is conceivable that more than one parametric resonator circuit 5, 5a, 5b, 5c, 5d is connected with a neuronal probe device 16. Finally, it is also conceivable that all of the parametric resonator circuits 5, 5a, 5b, 5c, 5d are connected with a neuronal probe device 16.

[0077] An arrangement according to FIGS. 5 to 5c has the advantage of enlarging the field of view beyond an individual parametric resonator circuit 5, 5a, 5b, 5c, 5d and without sacrificing detection sensitivity. The overlap between the parametric resonator circuits 5, 5a, 5b, 5c, 5d is small and serves the purpose of minimizing signal voids. By making each individual parametric resonator circuit 5, 5a, 5b, 5c, 5d sensitive to a unique pumping frequency ω3a, ω3b, ω3c, ω3d, each parametric resonator circuit 5, 5a, 5b, 5c, 5d can individually be turned on or off by the wireless pump signal.

[0078] In FIG. 5a, a sequential acquisition mode of the wireless detection unit 4 is displayed. At a time t1, only the left-bottom parametric resonator circuit 5a is tuned to respond to a pump signal 3, 3a with a frequency at ω3a, so that only signals by this resonator bottom parametric resonator circuit 5a are detected. As already outlined, the use of the at least one gradient magnet 26 allows to divide the region to detect in acquisition slices 31. In FIG. 5a, the left-bottom parametric resonator circuit 5a is in direct contact with the first acquisition slice 31a. Thus, at the time t1, the first input signal 13 from the first acquisition slice 31a is detected. At the time t2, the parametric resonator circuit 5b is activated with a pump signal 3, 3b at a frequency ω3b and the first input signal 13 from the second acquisition slice 31b is detected.

[0079] In FIG. 5b, a simultaneous acquisition mode of the wireless detection unit 4 is displayed. The parametric resonators 5a and 5b are activated simultaneously by applying two pump signals 3, 3a, 3b with the frequencies ω3a and ω3b simultaneously. The first input signal 13 from the acquisition slice 31 is detected by both parametric resonators 5a and 5b. The first output signal 11 from each parametric resonator 5a and 5b is individually encoded, such that it may be assigned to each parametric resonator 5a and 5b. Such an encoding may already be apparent by the choice of the third frequency ω3a and ω3b, since the idler frequency is ω3a-ω1a and ω3b−ω1b. By mathematically separating the signal contributions of each parametric resonator 5a and 5b at their respective frequency bands, the single-channel receiver may be multiplexed into multiple channels, but without the need for the expensive console.

[0080] In FIG. 5c, a hybrid acquisition mode of the wireless detection unit 4, which is a combination of a sequential acquisition mode and a simultaneous acquisition mode of the wireless detection unit 4, is shown. Along the horizontal direction X of the quadrilateral, the first acquisition slice 31, 31a extends. At the time t1, the parametric resonators 5a and 5b are activated simultaneously by applying two pump signals 3, 3a, 3b with the frequencies ω3a and ω3b simultaneously. At the time t2, the parametric resonators 5c and 5d are activated simultaneously by applying two pump signals 3, 3c, 3d with the frequencies ω3c and ω3d simultaneously. These acquisition paradigms allow to run specific imaging sequences based on the acquisition modes.

[0081] All the features disclosed in the application documents are claimed as being essential to the invention if, individually or in combination, they are novel over the prior art.

LIST OF REFERENCE NUMERALS

[0082] 1 system [0083] 2 pump signal generator [0084] 3 pump signal [0085] 3a pump signal with frequency ω3a [0086] 3b pump signal with frequency ω3b [0087] 3c pump signal with frequency ω3c [0088] 3d pump signal with frequency ω3d [0089] 4 wireless detection unit [0090] 5 parametric resonator circuit [0091] 5a first parametric resonator circuit [0092] 5b second parametric resonator circuit [0093] 5c third parametric resonator circuit [0094] 5d fourth parametric resonator circuit [0095] 6 varactor [0096] 7 varactor [0097] 8 capacitor [0098] 9 inductance [0099] 9a first inductance [0100] 9b second inductance [0101] 10 first pump current [0102] 11 first output signal [0103] 11a secondary first output signal [0104] 12 second pump current [0105] 13 first input signal [0106] 14 second output signal [0107] 15 second input signal [0108] 16 neuronal probe device [0109] 17 external receiving device [0110] 18 first input current [0111] 19 resulting current [0112] 19a secondary resulting current [0113] 20 device for image processing [0114] 21 center leg [0115] 22 ground electrode [0116] 23 MRI scanner device [0117] 24 subject [0118] 25 primary magnet [0119] 26 gradient magnet [0120] 27 RF-signal generator [0121] 28 user interface [0122] 29 symmetric current flow [0123] 30 anti-symmetric current flow [0124] 31 acquisition slices [0125] 31a first acquisition slice [0126] 31b second acquisition slice [0127] B0 magnetic field of primary magnet [0128] BG gradient magnetic field [0129] BRF RF-pulse [0130] t1 first time [0131] t2 second time [0132] X horizontal direction [0133] Y vertical direction