Siemens Aktiengesellschaft

Siemens Aktiengesell Schaft

Helmut Kess

Ralph Meissner

Wilfried Schnell

Hubertus Fischer

Norbert Krause

Georg Rauh

Ludger Freisen

The present embodiments relate to apparatuses and methods for detecting unplugged local coils in a magnetic resonance tomography (MRT) device. The MRT device includes a local coil that has a RFID tag configured to detect transmitted RFID signals. When at least one transmitted RFID signal is detected, at least one unplugged local coil is detected in the MRT device.

Detecting unplugged local coils in a nuclear magnetic resonance tomograph

A magnetic resonance system has a basic field magnet that generates a static basic magnetic field that is essentially homogeneous within an examination volume, the basic magnetic field having a basic direction. At least one tool can be inserted into the examination volume and can be removed from it. The at least one tool has a number of Hall elements. Each Hall element of the at least one tool is fashioned such that a binary signal emitted by said Hall element characterizes whether the basic magnetic field has a component that, relative to a respective element direction of the respective Hall element, is greater than a threshold. The respective element directions of the respective Hall elements differ from one another in pairs. The Hall elements of the at least one tool communicate in terms of data with an evaluation device of the magnetic resonance system to transmit the binary signal that it emits. The evaluation device uses the transmitted binary signal to determine an orientation of the at least one tool relative to the basic direction and takes additional measures depending on this orientation.

Magnetic resonance system with orientation detection of tools

An arrangement for monitoring the switching state of a switch has a monitoring circuit that monitors a circuit containing a first switch. The monitoring circuit has RFID electronics and a second switch. An outlet of the RFID electronics is connected in series with an RFID antenna, and the second switch is connected to an input of the RFID electronics, such that the second switch opens or closes the monitoring circuit dependent on the switching state thereof. The first and second switches are coupled to each other so that the switching state of the second switch is controlled as a function of the switching state of the first switch, so the switching state of the second switch represents the switching state of the first switch. An RFID reading device is within range of the RFID antenna, and feeds a query signal via the RFID antenna into the monitoring circuit to determine the representative switching state of the first switch via the switching state of the second switch.

Arrangement for monitoring a switching state of a switch

A radio-frequency transmission device for a magnetic resonance system to generate magnetic resonance exposures of an examination region of an examination subject, has: a first radio-frequency transmission antenna that emits radio-frequency signals in the examination region, a radio-frequency amplifier that supplies the first radio-frequency transmission antenna, with radio-frequency signals with a predetermined radio-frequency transmission power, and a second radio-frequency transmission antenna fashioned to label a medium flowing in the examination region and/or examination regions via emission of labeling radio-frequency signals, such that the medium can be identified in the generated magnetic resonance exposures of the examination region. The second radio-frequency transmission antenna is coupled with the radio-frequency amplifier to supply the first radio-frequency transmission antenna, such that it likewise supplies the second radio-frequency transmission antenna with radio-frequency signals with a predetermined radio-frequency transmission power for the emission of radio-frequency labeling signals.

Magnetic resonance rf transmission arrangement and method with commonly fed labeling and excitation antennas

A local coil arrangement for magnetic resonance applications has an acquisition coil for acquisition of a magnetic resonance signal excited in an examination subject by means of a transmission coil; and a transponder. The transponder is coupled to the acquisition coil such that it can be fed with electrical energy via the acquisition coil The transponder is fashioned to send a transponder signal on a transponder frequency when and as soon as an excitation signal induced in the acquisition coil by means of the transmission coil exceeds a threshold. When the control device receives the transponder signal, it adjusts the further operation of the transmission antenna or operates it only with reduced power.

Magnetic resonance local coil arrangement and method for communicating an overload occurrence

In a circuit for connection of at least two signal sources with at least one signal output, the signal sources are connected with a control unit. The control unit activates or deactivates the signal sources by transmission of control signals. Each signal source is connected with a blocking unit. Each blocking unit is connected with the control unit. The blocking unit can block or enable a connection between the signal source and the signal output, with the connection being automatically enabled when the signal source is activated.

Circuit for connection of at least two signal sources with at least one signal output

A circuit arrangement for connection of at least two local coils of a magnetic resonance apparatus with at least two evaluation units has at least two sheath wave barriers arranged so that magnetic fields caused by them substantially cancel one another.

Circuit arrangement for transferring signals form local MR coils to evaluation units

In a double resonance antenna arrangement for a nuclear magnetic resonance apparatus having at least one conductor section that defines an examination region, a series circuit of a capacitive element and an inductive element is connected in parallel with at least a part of the conductor section.

Double resonance antenna arrangement for a nuclear magnetic resonance

In a circularly polarizing local antenna for a nuclear magnetic resonance imaging apparatus, a first antenna system is fashioned as a frame coil. A second antenna system has two sub-coils arranged lying opposite one another, which are both penetrated by the frame coil. The combination of the first and second antenna systems exhibits a circularly polarizing characteristic in a volume that lies inside the frame coil and outside the subcoils.

Circularly polarizing local antenna for a nuclear magnetic resonance

A transmission antenna for a nuclear magnetic resonance apparatus has a capacitor connected in parallel with it via at least one PIN diode, and a reception antenna for the apparatus has a capacitor connected directly in parallel with it and an inductor connected in parallel with it via a PIN diode. The PIN diodes are connected to a control voltage in a series circuit. Given a first direction of the control voltage, the PIN diodes are conductive, so that the transmission antenna is tuned to the nuclear magnetic resonant frequency due to cut-in of the capacitor and the reception antenna is detuned to the cut-in of the inductor. Given a second direction of the control voltage, the reception antenna is tuned to the nuclear magnetic resonant frequency and the transmission antenna is detuned with respect to the nuclear magnetic resonant frequency. An unwanted, local super-elevation of the RF power cannot occur with this antenna.

Error-proof decoupling of transmission and reception antennas in a

A nuclear magnetic resonance tomography apparatus has a coil for generating a basic magnetic field, a gradient coil and measuring coils. A capacitor arrangement precisely adjusts the resonance of the measurement coil to the basic field coil. An iron-free dc motor is disposed within the field generated by the basic field coil for physically adjusting the plates of the capacitors connected in the circuit including the measurement coil. The rotor and coils of the iron-free dc motor are disposed within the basic magnetic field such that the basic magnetic field functions as the stator field for operating the motor.

NMR tomography apparatus having iron-free dc motors for capacitor

A PIN diode switch suitable for switching radio-frequency voltages has a series circuit of two oppositely polarized PIN diodes, with a control current supplied to the junction between the two PIN diodes through the collector-emitter path of a transistor and through an inductor. The necessity of using a high-voltage power pack to generate a high reverse bias in order to avoid limiting the amplitude of the radio frequency voltage to be switched is not necessary, as in conventional PIN diode switches.

PIN diode switch

A nuclear magnetic resonance apparatus which is capable of identifying either spectra or images of an examination subject uses a body resonator, such as a whole-body antenna, for transmitting radio frequency signals at a wave length .lambda. to induce nuclear magnetic resonance phenomena in the examination subject, and a surface coil for receiving the resulting nuclear magnetic resonance signals. For decoupling the body resonator from the surface coil, a .lambda./4 line is connected to the surface coil. A terminating end of the .lambda./4 line is short-circuited during emission of radio frequency pulses by the body resonator, and is opened during reception of nuclear magnetic resonance signals using the surface coil. An effective detuning of the body resonator is thus achieved during the reception event, and at the same time the transmission event is minimally influenced.

Nuclear magnetic resonance apparatus for the identification of spectra

For the representation of images of regions selected from the interior of an examination subject, coils are provided for the application of a primary magnetic field and of magnetic gradient fields to the examination subject. An electrical conductor configuration detects the deflection of the atomic nuclei of the examination subject from their position of equilibrium as a result of high frequency magnetic excitation pulses. The configuration is formed by two interspersed individual conductor configurations adapted for respective different measurement frequencies. Each configuration comprises parallel conductors connected at their ends and arranged in spaced relation to an electrically grounded surface to form a transmission line configuration resonant at a respective one of the measurement frequencies.

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Erlangen, Germany

Helmut Kess