Abstract: The invention relates to a high-frequency system for an MR apparatus with a high-frequency coil arrangement comprising a plurality of resonator elements (104), which is connected to a transmit unit (106), where a respective transmit channel (1–8) of the transmit unit (106) is assigned to the resonator elements (104). In order to provide a high-frequency system of this kind at low cost, by means of which a high frequency field can be generated in an examination volume (100) with a field distribution that can be preselected flexibly and variably, the invention proposes that the transmit unit (106) is equipped with a plurality of high-frequency amplifiers (107), the inputs of which can receive low-power transmit signals via a first controllable multiplexer/distributor network (108), in which the output signals of the high-frequency amplifiers (107) can be distributed over the transmit channels (1–8) via a second controllable multiplexer/distributor network (109).

Abstract: An RF coil system for a magnetic resonance imaging apparatus whereby a substantially computer-aided and hence automatically optimized image quality in respect of signal-to-noise ratio and resolution can be achieved in dependence on the type and size of the object to be imaged, without time-consuming replacement or manual positioning of the RF coil system being necessary. To this end, the coil system (A) includes a plurality of single RF coils (Sx) which are essentially decoupled from one another and have a different size and/or different position, as well as a control device with a plurality of transmission units which are associated with a respective RF coil and whereby one or more RF coils can be selected and supplied with an RF pulse having an independently adjustable amplitude and/or phase and/or pulse shape. The invention also relates to a magnetic resonance imaging apparatus provided with such an RF coil system.

Abstract: The invention relates to an arrangement for generating RF fields in the examination volume (100) of an MR apparatus. A plurality of resonator segments are arranged around the examination volume (100) within the gradient tube (103), said resonator segments being connected together so as to form a body coil. Each resonator segment is provided with a conductor element (104) which is constructed as a planar strip and extends parallel to the longitudinal axis of the main field magnet. The resonator segments are electromagnetically decoupled from one another by means of intermediate capacitances, so that a separate transmission channel (1 to 8) can be associated with each resonator segment, the RF feeding into the relevant resonator segment taking place via said channel.

Abstract: The invention relates to an MR apparatus that is provided with an open magnet system and a quadrature coil system that includes a resonator that is tuned by tuning capacitors on at least one of the two sides of the steady magnetic field, said resonator including two large-area electrical conductors that are situated at a distance from one another and are connected to one another in a number of connection points that are distributed along the circumference, and are also provided with at least two terminals that are distributed along the circumference in order to receive or generate RF magnetic fields that are mutually offset in phase. The invention also relates to a corresponding quadrature coil system.

Abstract: The invention relates to a magnetic resonance imaging apparatus (MRI apparatus) which is provided with an open magnet system and in which there are generated a basic magnetic field (vertical field) which perpendicularly traverses an object to be examined and also an RF field, which MRI apparatus is characterized notably in that coupling effects between a dipole structure (11, 12, 13), formed by the magnet system (10), and an RF conductor structure (20, 21, 22) are eliminated at least to a high degree by shifting or detuning a self-resonant frequency of the dipole structure relative to the MR frequency or by suppressing a self-resonant frequency of the dipole structure.

Abstract: The invention relates to an arrangement for generating RF fields in the examination volume (100) of an MR apparatus. A plurality of resonator segments are arranged around the examination volume (100) within the gradient tube (103), said resonator segments being connected together so as to form a body coil. Each resonator segment is provided with a conductor element (104) which is constructed as a planar strip and extends parallel to the longitudinal axis of the main field magnet. The resonator segments are electromagnetically decoupled from one another by means of intermediate capacitances, so that a separate transmission channel (1 to 8) can be associated with each resonator segment, the RF feeding into the relevant resonator segment taking place via said channel.

Abstract: The invention relates to an RF surface resonator (RF coil) for transmitting and/or receiving circularly polarized electromagnetic waves, which resonator is intended in particular for magnetic resonance imaging (MRI) apparatus in which a basic magnetic field (vertical field) that extends perpendicularly through an object to be examined and a circularly polarized RF field are generated. Various steps are proposed so as to achieve a desired variation of the field strength in the radial direction as well as in the direction of circulation.

Abstract: The invention relates to an RF coil system for an open MR apparatus. The system includes a plurality of resonator elements which are arranged at the area of a patient (102) positioned in the examination volume of an MR apparatus. The resonator elements are constructed at least partly as solenoid elements (104) whose conductor elements form open turns which are arranged around the patient (102). It is thus achieved that the RF field generated in the transmission mode and the sensitivity profile in the detection mode are limited as strictly as possible to the examination volume of interest. At the same time RF field strengths that are adequate for medical imaging can be generated without exposing the patient to an unacceptable load.

Abstract: An RF coil system for a magnetic resonance imaging apparatus whereby a substantially computer-aided and hence automatically optimized image quality in respect of signal-to-noise ratio and resolution can be achieved in dependence on the type and size of the object to be imaged, without time-consuming replacement or manual positioning of the RF coil system being necessary. To this end, the coil system (A) includes a plurality of single RF coils (Sx) which are essentially decoupled from one another and have a different size and/or different position, as well as a control device with a plurality of transmission units which are associated with a respective RF coil and whereby one or more RF coils can be selected and supplied with an RF pulse having an independently adjustable amplitude and/or phase and/or pulse shape. The invention also relates to a magnetic resonance imaging apparatus provided with such an RF coil system.

Abstract: The invention relates to an RF coil system for an open MR apparatus. The system includes a plurality of resonator elements which are arranged at the area of a patient (102) positioned in the examination volume of an MR apparatus. The resonator elements are constructed at least partly as solenoid elements (104) whose conductor elements form open turns which are arranged around the patient (102). It is thus achieved that the RF field generated in the transmission mode and the sensitivity profile in the detection mode are limited as strictly as possible to the examination volume of interest. At the same time RF field strengths that are adequate for medical imaging can be generated without exposing the patient to an unacceptable load.

Abstract: The invention relates to an MR apparatus that is provided with an open magnet system and a quadrature coil system that includes a resonator that is tuned by tuning capacitors on at least one of the two sides of the steady magnetic field, said resonator including two large-area electrical conductors that are situated at a distance from one another and are connected to one another in a number of connection points that are distributed along the circumference, and are also provided with at least two terminals that are distributed along the circumference in order to receive or generate RF magnetic fields that are mutually offset in phase. The invention also relates to a corresponding quadrature coil system.

Abstract: The invention relates to a magnetic resonance imaging apparatus (MRI apparatus) which is provided with an open magnet system and in which there are generated a basic magnetic field (vertical field) which perpendicularly traverses an object to be examined and also an RF field, which MRI apparatus is characterized notably in that coupling effects between a dipole structure (11, 12, 13), formed by the magnet system (10), and an RF conductor structure (20, 21, 22) are eliminated at least to a high degree by shifting or detuning a self-resonant frequency of the dipole structure relative to the MR frequency or by suppressing a self-resonant frequency of the dipole structure.

Abstract: The invention relates to an RF surface resonator (RF coil) for transmitting and/or receiving circularly polarized electromagnetic waves, which resonator is intended in particular for magnetic resonance imaging (MRI) apparatus in which a basic magnetic field (vertical field) that extends perpendicularly through an object to be examined and a circularly polarized RF field are generated. Various steps are proposed so as to achieve a desired variation of the field strength in the radial direction as well as in the direction of circulation.

Abstract: The invention relates to an MR apparatus which includes a cylindrical main field magnet for generating a uniform, steady magnetic field whose cylindrical shape defines a symmetry axis, a gradient coil system which encloses the symmetry axis and includes a plurality of gradient coils, an RF coil system which is situated inside the gradient coil system and includes a plurality of mutually offset conductors which extend parallel to the symmetry axis, and a table top for accommodating an object to be examined.