Abstract: The invention provides for an RF antenna system (100, 1014, 1014?) for transmitting RF excitation signals into and/or for receiving MR signals from an MR imaging system's (1000, 1100, 1200) imaging volume (1015). The magnetic resonance imaging antenna comprises: a coil former (100, 1014, 1014?) adjacent to the imaging volume (1015); and a resonator (400, 500, 600) attached to the coil former and tuned to at least one resonant frequency formed from electrical connections (304), between multiple capacitors (302). The multiple capacitors are distributed in a periodic pattern (300, 700, 800, 900) about and along the coil former.

Abstract: An RF volume resonator system is disclosed comprising a multi-port RF volume resonator (40, 50; 60), like e.g. a TEM volume coil or TEM resonator, or a birdcage coil, all of those especially in the form of a local coil like a head coil, or a whole body coil, and a plurality of transmit and/or receive channels (T/RCh1, . . . T/RCh8) for operating the multi-port RF volume resonator for transmitting RF excitation signals and/or for receiving MR relaxation signals into/from an examination object or a part thereof. By the individual selection of each port (P1, . . . P8) and the appropriate amplitude and/or frequency and/or phase and/or pulse shapes of the RF transmit signals according to the physical properties of an examination object, a resonant RF mode within the examination object with an improved homogeneity can be excited by the RF resonator.

Abstract: A radio frequency antenna device (30) for use in a magnetic resonance imaging system (10), the magnetic resonance imaging system (10) being configured for acquiring magnetic resonance images of at least a portion of a subject of interest (20); the radio frequency antenna device (30) comprising—at least one radio frequency antennae (32) that is configured for being fed with radio frequency power from at least one radio frequency channel and for applying a radio frequency field B to nuclei of or within the portion of the subject of interest (20) for magnetic resonance excitation, —at least one pickup circuit (46), including an electric or electronic device having a non-linear current-voltage characteristic, —wherein the at least one pickup circuit (46) is configured to provide a trigger signal (56) upon a transfer of the electric or electronic device between a state of high impedance and a state of low impedance, the trigger signal (56) being exploitable for shutting down a supply of radio frequency power to th

Abstract: A radio-frequency coil assembly (18), for use in a magnetic resonance imaging system (10), includes a plurality of coil elements (18n). The coil elements (18n) are connected to a decoupling network (40) which includes a plurality of decoupling elements (40n,x) connected (via transmission lines) to pairs of coil elements (18n, 18x) at corresponding ports (64n,64x) from which the coil can be fed. The decoupling elements (40n,x) compensate for mutual coupling between pairs of corresponding coil elements. An inductive coupling loop (51n), with a constant or adjustable mutual inductance, inductively couples the associated coil element (18n) to the corresponding decoupling network port (64n). Transmission lines (52n) electrically connect each inductive coupling loop (51n) to the decoupling network (40) at the corresponding port (64n). Each transmission line (52n) has an electrical length of k?/2 where k=0, 1, 2, 3 . . .

Abstract: The present invention provides a radio frequency (RF) antenna device (140) for applying an RF field to an examination space (116) of a magnetic resonance (MR) imaging system (110), whereby the RF antenna device (140) is provided having a tubular body, the RF antenna device (140) is segmented in its longitudinal direction (154), and each segment (162, 164) is provided with at least one activation port. The result is that each mode, corresponding to an activation port, may be controlled individually. Accordingly, the inhomogeneity of the subject of interest in this direction, i.e. in the longitudinal direction of the RF antenna device, can directly be addressed. There are different ways to build up a z-segmented RF antenna device.

Abstract: The invention relates to a system comprising an array of two or more receiving antennas (11, 12, 13) for receiving RF signals, each receiving antenna being connected, via a matching network (19, 20, 21), to a low-noise amplifier (22, 23, 24) presenting an input impedance to the matching network (19, 20, 21), each chain consisting of a receiving antenna (11, 12, 13), a matching network (19, 20, 21) and a low-noise amplifier (22, 23, 24) constituting a part of a receiving channel of the system, the matching networks (19, 20, 21) transforming optimum impedances of the low-noise amplifiers (22, 23, 24), the optimum impedances providing optimum noise performance of the low-noise amplifiers (22, 23, 24), wherein each receiving channel comprises at least one switchable impedance (28, 29, 30) at the input of each low-noise amplifier (22, 23, 24) for switching the input impedance as presented to each matching network (19, 20, 21) to a value being the complex conjugate of the optimum impedance of the respective low-noi

Abstract: A radio frequency transmission system for a magnetic resonance system includes a radio frequency power amplifier generating an input radio frequency signal that excites magnetic resonance in target nuclei and is designed for feeding an impedance Z0, and a multi-channel radio frequency coil having N radio frequency channels where N>1. Further, a power splitter includes (i) a parallel radio frequency connection point at which the N channels of the radio frequency coil are connected in parallel to define an output impedance at the parallel radio frequency connection point, and (ii) an impedance matching circuit connecting the radio frequency power amplifier with the radio frequency connection point and configured to provide impedance matching between the radio frequency power amplifier and the output impedance at the connection point.

Abstract: The Magnetic Resonance Imaging (MRI) system includes a radio-frequency transmitter with multiple transmit channels. The MRI system includes an impedance matching network (320, 1402, 1502, 1602) for matching the radio-frequency transmitter to a remotely adjustable radio-frequency antenna (310, 1504, 1602) with multiple antenna elements (312, 314, 316, 318, 1404). The MRI system includes a processor (336) for controlling the MRI system. The execution of the instructions by the processor causes it to: measure (100, 200) a set of radio-frequency properties (352) of the radio-frequency antenna, calculate (102, 202) a matching network command (354) using the set of radio-frequency properties and a radio frequency model (366), and adjust (104, 204) the impedance matching network by sending the matching network command to the impedance matching network, thereby enabling automatic remote impedance matching.

Abstract: Abstract: An RF volume resonator system is disclosed comprising a multi-port RF volume resonator (40, 50; 60), like e.g. a TEM volume coil or TEM resonator, or a birdcage coil, all of those especially in the form of a local coil like a head coil, or a whole body coil, and a plurality of transmit and/or receive channels (T/RCh1, . . . T/RCh8) for operating the multi-port RF volume resonator for transmitting RF excitation signals and/or for receiving MR relaxation signals into/from an examination object or a part thereof. By the individual selection of each port (P1, . . . P8) and the appropriate amplitude and/or frequency and/or phase and/or pulse shapes of the RF transmit signals according to the physical properties of an examination object, a resonant RF mode within the examination object with an improved homogeneity can be excited by the RF resonator.

Abstract: The invention provides for a therapeutic apparatus comprising a tissue heating system (302, 480, 482). The therapeutic apparatus further comprises a magnetic resonance imaging system (300) for acquiring magnetic resonance thermometry data (366) from nuclei of a subject (318) located within an imaging volume (330). The therapeutic apparatus further comprises a radiation therapy system (304, 592) for irradiating an irradiation volume (316, 516) of the subject, wherein the irradiation volume is within the imaging volume. The therapeutic apparatus further comprises a controller (354) for controlling the therapeutic apparatus. The controller is adapted for acquiring (100, 210) magnetic resonance thermometry data repeatedly using the magnetic resonance imaging system. The controller is adapted for heating (102, 208) at least the irradiation volume using the tissue heating system. The heating is controlled using the magnetic resonance thermometry data.

Abstract: A radio-frequency coil assembly (18), for use in a magnetic resonance imaging system (10), includes a plurality of coil elements (18n). The coil elements (18n) are connected to a decoupling network (40) which includes a plurality of decoupling elements (40n,x) connected (via transmission lines) to pairs of coil elements (18n, 18x) at corresponding ports (64n,64x) from which the coil can be fed. The decoupling elements (40n,x) compensate for mutual coupling between pairs of corresponding coil elements. An inductive coupling loop (51n), with a constant or adjustable mutual inductance, inductively couples the associated coil element (18n) to the corresponding decoupling network port (64n). Transmission lines (52n) electrically connect each inductive coupling loop (51n) to the decoupling network (40) at the corresponding port (64x). Each transmission line (52n) has an electrical length of k?/2 where k=0,1,2,3 . . .

Abstract: The invention relates to a magnetic resonance method of electric properties tomography imaging of an object, the method comprising: applying an excitation RF field to the object via a coil at a first spatial coil position (402), acquiring resulting magnetic resonance signals via a receiving channel from the object, determining from the acquired magnetic resonance signals a first phase distribution and a first amplitude of a given magnetic field component of the excitation RF field of the coil at the first coil position (402), repeating these steps with a coil at a second different spatial coil position (404), to obtain a second phase distribution, determining a phase difference between the first and second phase distribution, determining a first and a second complex permittivity of the object, the first complex permittivity comprising the first amplitude of the given magnetic field component and the second complex permittivity comprising the second amplitude of the given magnetic field component and the phase

Abstract: A magnetic resonance imaging apparatus produces calculations of local specific energy absorption rates (SAR) by calculating an electrical permittivity map of a subject. The electric permittivity is calculated by measuring the components of the B1 field induced by a radio frequency (RF) coil (16). The Hx and Hy components of the B1 field can be directly measured. The Hz component is measured by encoding it into the phase of the resonance signals. Alternately, Hz can be calculated by solving Gauss's law for magnetism. Hz can also be estimated by finding the z component of the electric field. In the specific case of a birdcage RF coil, Hz can be estimated by using a model of the RF coil and a subject, a model of the RF coil alone, or setting Hz to a constant.

Abstract: The invention relates to a system comprising an array of two or more receiving antennas (11, 12, 13) for receiving RF signals, each receiving antenna being connected, via a matching network (19, 20, 21), to a low-noise amplifier (22, 23, 24) presenting an input impedance to the matching network (19, 20, 21), each chain consisting of a receiving antenna (11, 12, 13), a matching network (19, 20, 21) and a low-noise amplifier (22, 23, 24) constituting a part of a receiving channel of the system, the matching networks (19, 20, 21) transforming optimum impedances of the low-noise amplifiers (22, 23, 24), the optimum impedances providing optimum noise performance of the low-noise amplifiers (22, 23, 24), wherein each receiving channel comprises at least one switchable impedance (28, 29, 30) at the input of each low-noise amplifier (22, 23, 24) for switching the input impedance as presented to each matching network (19, 20, 21) to a value being the complex conjugate of the optimum impedance of the respective low-noi

Abstract: A coil (36) includes coil elements (381, 382, . . . , 38n). The coil (36) can transmit radio frequency excitation pulses into an examination region (14) and/or receive responsive radio frequency pulses from the examination region (14). A compensation network (42) includes decoupling segments (98), which each has a selected electrical length at least of a quarter wavelength (?/4) and is electrically coupled to an associated coil element (381, 382, . . . , 38n) and a reactive network (100). The compensation network (42) at least compensates coupling between the coil elements (381, 382, . . . , 38n).

Abstract: For detuning of radio-frequency coils (in magnetic resonance imaging and spectroscopy, for example), a conducting element (102) of a transmission cable is configured to form a primary resonant circuit tunable to at least one first resonance frequency. A second conducting element (104) of the transmission cable is configured to form a switching circuit that is electrically insulated from and reactively coupled via inductive coupling and/or capacitive coupling to the primary resonant circuit, and is adapted to tune the primary resonant circuit to at least one second resonance frequency, thereby detuning the primary resonant circuit.

Abstract: A radio frequency transmission system for a magnetic resonance system includes a radio frequency power amplifier (40) generating an input radio frequency signal that excites magnetic resonance in target nuclei and is designed for feeding an impedance Zo, a multi-channel radio frequency coil (18) having N radio frequency channels where N>1, and a power splitter (44) including (i) a parallel radio frequency connection point (50) at which the N channels of the radio frequency coil are connected in parallel to define an output impedance at the parallel radio frequency connection point, and (ii) an impedance matching circuit (54) connecting the radio frequency power amplifier with the radio frequency connection point and configured to provide impedance matching between the radio frequency power amplifier and the output impedance at the connection point.

Abstract: A method and circuit arrangement for operating multi-channel transmit/receive antenna devices or arrangements is used in magnetic resonance imaging (MRI) systems. Full independent control of complete multi-channel RF transmit and receive chains can be conducted in a flexible way and new options like RF shimming, transmit sensitivity encoding (TransmitSENSE), RF encoding, determination of S- or Z-matrix prior to spin echo measurements, calibration, SAR (specific absorption rate) reduction etc. can be utilized or improved.

Abstract: The present invention relates to a magnetic resonance imaging system (1) comprising a plurality of RF coils (4) forming a multi-coil array and furthermore to a magnetic resonance imaging method for such a system. In order to provide an MR imaging system and method in which a desired excitation pattern is achieved in a simple way, it is suggested to utilize an analytical procedure how to combine the single coil elements to obtain the most homogeneous B1 excitation possible with a given coil array. In other words, the homogeneity of the B1 field is improved in a very simple way. The sensitivity of each RF coil (4) of the coil array is scaled or weighted by a complex factor, i.e. phase and amplitude of each coil drive signal is adjusted accordingly. These complex factors are determined analytically utilizing the sensitivities S(8) of the coil elements (4) and the desired excitation pattern P (IO, 11). The invention allows an optimized control of the field distribution (RF shimming) for arbitrary RF coil arrays.

Abstract: For detuning of radio-frequency coils (in magnetic resonance imaging and spectroscopy, for example), a conducting element (102) of a transmission cable is configured to form a primary resonant circuit tunable to at least one first resonance frequency. A second conducting element (104) of the transmission cable is configured to form a switching circuit that is electrically insulated from and reactively coupled via inductive coupling and/or capacitive coupling to the primary resonant circuit, and is adapted to tune the primary resonant circuit to at least one second resonance frequency, thereby detuning the primary resonant circuit.