METHOD FOR TRANSFERRING AT LEAST ONE SPEECH SIGNAL OF A PATIENT DURING A MAGNETIC RESONANCE IMAGING EXAMINATION, AND MAGNETIC RESONANCE IMAGING DEVICE

Abstract

Techniques are disclosed for transferring at least one speech signal of a patient during a magnetic resonance imaging examination, wherein the speech signal is recorded by a speech recording device of a wireless communication device assigned to the patient and transmitted at least as part of a communication signal to a receive device of the magnetic resonance imaging device. The communication signal is a modulated signal or is generated from a modulated signal, and to generate the modulated signal the speech signal is modulated onto a carrier signal. The modulated signal is generated by way of a modulation with reduction of the level of the carrier signal.

Claims

1. A method for transferring a speech signal of a patient during a magnetic resonance imaging examination, comprising: recording the speech signal via a speech recording device of a wireless communication device; generating a modulated signal by modulating the speech signal onto a reduced amplitude carrier signal, the reduced amplitude carrier signal having a reduced amplitude as a result of reducing, by a reduction factor, an amplitude of a carrier signal used for transmission in accordance with a communication protocol; and transmitting the speech signal as part of a communication signal to a receiver of the magnetic resonance imaging device, wherein the communication signal is (i) the modulated signal, or (ii) generated from the modulated signal.

2. The method as claimed in claim 1, wherein the reduced amplitude carrier signal and a sideband of the modulated signal are transmitted as the communication signal.

3. The method as claimed in claim 1, wherein the reduced amplitude carrier signal and two sidebands of the modulated signal are transmitted as the communication signal, and wherein one of the sidebands is filtered out of the communication signal in the receiver prior to demodulation.

4. The method as claimed in claim 1, wherein the act of generating the modulated signal comprises: generated the modulated signal by modulating the speech signal onto the reduced amplitude carrier signal using a double balanced mixer.

5. The method as claimed in claim 4, wherein the double balanced mixer comprises a Gilbert cell.

6. The method as claimed in claim 1, further comprising: reconstructing, via a phase-locked loop of the receiver, the reduced amplitude carrier signal to generate a reconstructed carrier signal for demodulation of the communication signal.

7. The method as claimed in claim 6, wherein the phase-locked loop of the receiver is implemented in a digital signal processor.

8. The method as claimed in claim 6, further comprising: maintaining, during a transmit phase of the magnetic resonance imaging device, a frequency of an oscillator of the phase-locked loop at a frequency of the oscillator prior to or at a start of the transmit phase, and wherein the reconstructed carrier signal is generated during the transmit phase having the maintained frequency of the oscillator.

9. The method as claimed in claim 1, wherein the receiver is configured to receive (i) magnetic resonance signals generated during an imaging sequence of the magnetic resonance imaging device, and (ii) the communication signal.

10. A magnetic resonance imaging device for transferring a speech signal of a patient during a magnetic resonance imaging examination, comprising: communication circuitry configured to: record the speech signal; generate a modulated signal by modulating the speech signal onto a reduced amplitude carrier signal, the reduced amplitude carrier signal having a reduced amplitude as a result of reducing, by a reduction factor, an amplitude of a carrier signal used for transmission in accordance with a communication protocol; and transmit the speech signal as part of a communication signal to a receiver of the magnetic resonance imaging device, wherein the communication signal is (i) the modulated signal, or (ii) generated from the modulated signal; and a receiver configured to receive the communication signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

[0059] Further advantages and details of the present disclosure are disclosed in the following description of exemplary embodiments and by reference to the drawings, in which:

[0060] FIG. 1 shows an exemplary embodiment of a magnetic resonance imaging device according to the disclosure;

[0061] FIG. 2 shows a first block diagram of an exemplary embodiment of a method according to the disclosure; and

[0062] FIG. 3 shows a further block diagram of an exemplary embodiment according to the disclosure.

DETAILED DESCRIPTION

[0063] FIG. 1 illustrates an exemplary embodiment of a magnetic resonance imaging device 1 according to the disclosure. The magnetic resonance imaging device 1 comprises a scanner unit 2, in which a main magnet of the imaging device 1 is arranged. The scanner unit 2 further comprises a patient aperture 3, in which a patient positioning apparatus 4 with a patient 5 can be arranged.

[0064] The imaging device 1 further comprises a communication circuitry 6 (e.g. a communication arrangement), which has a wireless communication device 7, which can be assigned to the patient 5, and a receive device 8. Here, the receive device 8 is likewise embodied to receive magnetic resonance signals generated during an imaging sequence of the magnetic resonance imaging device 1.

[0065] The receive device 8 is further used to receive a communication signal, wherein the communication signal is transmitted from the communication device 7 to the receive device 8. The communication device 7 e.g. continuously records a speech signal of the patient 5 or an audio signal from the immediate vicinity of a head of the patient 5, and generates a communication signal from the speech signal. The communication signal is transmitted from the communication device 7 to the receive device 8. The communication device 7 therefore represents the transmitter configured to transfer the communication signal or the speech signal, and the receive device 8 represents the receiver.

[0066] FIG. 2 illustrates a schematic block diagram of the communication device 7. In an exemplary embodiment of a method for transferring at least one speech signal of the patient during a magnetic resonance imaging examination using the magnetic resonance imaging device 1, a communication signal is generated from the speech signal and transmitted from the communication device 7 to the receive device 8. The communication signal is generated in the communication device 7 as a modulated signal or from a modulated signal, as noted herein.

[0067] To generate the modulated signal, the speech signal is modulated onto a carrier signal, wherein the modulated signal is generated by way of a modulation with reduction of the level of the carrier signal. To record the speech signal, the communication device 7 comprises a speech acquisition device 9 embodied as a microphone, via which the speech signal ν.sub.m(t) can be recorded. Here, the speech signal ν.sub.m(t) corresponds to the sound recorded in the immediate vicinity of the patient 5 and can comprise e.g. words spoken by the patient 5.

[0068] The speech signal is modulated as a modulation signal onto a carrier signal ν.sub.c(t), wherein the carrier signal is generated by a carrier signal generator 10. The carrier signal generator 10 can be or comprise for example a temperature compensated crystal oscillator.

[0069] The frequency of the carrier signal ν.sub.c (t) is selected such that it lies slightly outside the frequencies received during the magnetic resonance imaging, but can still be received by the receive device 8 of the magnetic resonance imaging device 1. For example, a carrier frequency ω, between 62.5 MHz and 63 MHz can be selected for an imaging device 1, which on account of the magnetic field generated thereby, has a receive range of 63.6 MHz ±350 kHz. The speech signal ν.sub.m(t) can be modulated onto this accordingly as the modulation signal, wherein the bandwidth of the speech signal lies e.g. between 3 kHz and 5 kHz, depending on the desired quality of the speech signal transfer.

[0070] In the present exemplary embodiment, the modulated signal is generated by means of a dual sideband modulation with reduced carrier (DSB-RC). To this end, the communication device 7 comprises a double balanced mixer 11, which generates the corresponding modulated signal ν.sub.DSB-RC(t) from the speech signal ν.sub.m(t) and the carrier signal ν.sub.c(t). The double balanced mixer 11 can be implemented e.g. as a Gilbert cell.

[0071] The suppression of the carrier takes place through the introduction of an asymmetry into the circuitry of the double balanced mixer 11. In this case, a DC offset Vic is created at the modulation signal input at which the speech signal ν.sub.m(t) is present. Here, the DC offset V.sub.DC is generated by an offset device 12, for example a voltage source, of the communication device 7.

[0072] The modulated signal ν.sub.DSB-RC (t) generated by the mixer 11 is then transmitted via a transmit apparatus 13 of the communication device 7, which comprises for example one or more antennas, to the receive device 8. During the modulation, the level of the carrier signal ν.sub.c (t) is reduced in comparison with an amplitude modulation with a full carrier level, for example by any suitable factor such as between −10 dB and −40 dB, for example by −30 dB. This makes it possible to transfer a communication signal even during receive phases of a magnetic resonance imaging without impairing the imaging or the imaging quality.

[0073] FIG. 3 shows a block diagram illustrating the signal processing on the receiver side in an exemplary embodiment. The receive device 8 comprises at least one radio-frequency antenna unit 14, which can also be used to receive the image data during an imaging sequence of the imaging device 1. The receive device 8 also comprises a computing unit 15, which is realized for example as a digital signal processor. The communication signal ν.sub.DSB-RC(t) is received via the radio-frequency antenna unit 14 and fed to a first bandpass filter 16. From the received dual sideband signal with the reduced carrier, the bandpass filter 16 allows the portion of the reduced carrier and one of the sidebands, for example the upper sideband, to pass through and thus forms a single sideband signal with reduced carrier ν.sub.SSB-RC(t). This contains the carrier signal ν.sub.c(t) with an amplitude reduced by the factor k, or a level reduced by a factor k according to Eqn. 8.

[0074] The reconstruction of the carrier signal for the demodulation takes place in a phase-locked loop 17, which comprises for example a numerically controlled oscillator (NCO) as the local oscillator, the frequency of which is adjusted to the frequency co, of the carrier signal. Furthermore, an adjustment of the phase is also performed using the phase-locked loop, so that in the engaged state of the phase-locked loop 17 there is no phase shift in the local oscillator signal ν.sub.LO (t) generated accordingly.

[0075] For the demodulation of the speech signal ν.sub.m(t), the bandpass-filtered communication signal ν.sub.SSB-RC(t) and the signal of the local oscillator ν.sub.LO (t) are multiplied in a mixer 18. A second bandpass filter 19 can then be used to filter out the speech signal in the receiver ν.sub.m,RX(t) according to Eqn. 10 from the product ν.sub.SSB-RC(t)*ν.sub.LO(t) according to Eqn. 9.

[0076] Because during the excitation phases of the magnetic resonance imaging device 1 no reception of the communication signal occurs, and thus no frequency- or phase-corrected reconstruction of the carrier signal as the local oscillator signal ν.sub.LO (t) in the receive device 8 is possible, during an excitation phase of the imaging device 1 the frequency of the internal oscillator of the phase-locked loop 17 is set to a value of the frequency prior to or at the start of the transmit phase. The carrier signal ν.sub.LO(t) reconstructed with the fixed frequency can thus also be used briefly after the transmit phase for the demodulation of the communication signal, in this case the filtered communication signal ν.sub.SSB-RC(t), so that advantageously a speech transmission can already take place even before the re-engagement of the phase-locked loop 17 on a transmitted carrier signal portion of the communication signal. For example, this also improves the speech transfer during the imaging sequences of the magnetic resonance imaging device 1.

[0077] For defining the frequency of the local oscillator of the phase-locked loop 17, the phase-locked loop 17 can be placed in a holding state for example by a control device 20 of the imaging device 1 if an MR sequence, triggered for example by the control device 20, is impending or starts. After termination of the sequence, the phase-locked loop 17 is for example placed back into an operating mode, for example a carrier track mode, so that once again an engagement of the phase-locked loop 17 onto the carrier signal ν.sub.C (t) or the carrier signal portion of the filtered communication signal ν.sub.SSB-RC(t) can take place.

[0078] In an alternative exemplary embodiment of the method or in an alternative exemplary embodiment of an imaging device 1, it can be provided that the communication signal already generates a modulated signal formed by means of single sideband modulation with reduced carrier (SSB-RC) on the transmitter side, and transfers the modulated signal to the receive device 8. Alternatively, a DSB-RC signal, as shown in FIG. 2, can be generated as a modulated signal, wherein in the communication device 7 with the aid of a bandpass filter one of the sidebands of the modulated signal is filtered out to generate the subsequently-transmitted communication signal.

[0079] If a single sideband modulated signal ν.sub.SSB-RC (t) is received directly via the radio-frequency antenna 14 as the communication signal, it is possible to dispense with the first bandpass filter 16. In such an embodiment, too, it is advantageously possible for there to be no phase dependency during demodulation on the amplitude of the speech signal ν.sub.m,RX(t) determined on the receiver side, which depends on the phase angle between the signal ν.sub.LO(t) of the local oscillator and the carrier signal ν.sub.m(t).

[0080] In a further exemplary embodiment, it is possible for the filtering of one of the sidebands via the bandpass filter 16 to be dispensed with and for the dual sideband signal ν.sub.DSB-RC(t) received by the radio-frequency antenna 14 to be fed directly to the mixer 18. In this case, too, a transfer of the communication signal which has been generated from a modulated signal by way of a modulation with suppressed carrier is enabled.

[0081] Although the disclosure has been illustrated and described in greater detail on the basis of the exemplary embodiments, the disclosure is not limited by the disclosed examples and other variations can be derived herefrom by the person skilled in the art without leaving the scope of protection of the disclosure.

[0082] The various components described herein may be referred to as “devices” or “units.” Such components may be implemented via any suitable combination of hardware and/or software components as applicable and/or known to achieve the intended respective functionality. This may include mechanical and/or electrical components, processors, processing circuitry, or other suitable hardware components configured to execute instructions or computer programs that are stored on a suitable computer readable medium. Regardless of the particular implementation, such devices and units, as applicable and relevant, may alternatively be referred to herein as “circuitry,” “processors,” or “processing circuitry.”