Abstract: This invention relates to a method and device for reconstructing images of an object of interest. According to the invention, the device comprises a plurality of transmitting coils (102, 103, 115, 116) for generating a primary magnetic field; a plurality of measurement coils (121, 122, 129, 136); and means (150) for selecting and exciting a first pair of transmitting coils (102, 116) among the plurality of transmitting coils, wherein the first pair of transmitting coils (102, 116) are selected and excited in a way such that of transmitting coils is minimized at the location of at least one measurement coil among the plurality of measurement coils (121, 129). By minimizing the primary magnetic field at the location of the measurement coil(s), the device can reduce the dynamic range of measurement coils, resulting in simplified hardware design for magnetic induction tomography systems.

Abstract: A radio frequency coil (30) includes a radio frequency screen (34), a plurality of operative TEM elements (35) defined by parallel elongate conductive elements (36) coupled with the radio frequency screen and configured for operative connection with a multi-channel radio frequency driver (32), and a plurality of auxiliary elongate conductive elements (40, 50, 60, 70, 80a, 80b). Each auxiliary elongate conductive element is arranged parallel with and between two neighboring operative TEM elements and tuned to substantially decouple the two neighboring operative TEM elements, there being an auxiliary elongate conductive element disposed between each two neighboring operative TEM elements.

Abstract: A birdcage coil (10) for a magnetic resonance imaging device includes a plurality of rungs (12) coupled to a distal edge (15) of each of two endrings (16). The endrings (16) comprise a plurality of ring segments (18) that are separated by sets of capacitors (20, 22, 24). The rungs (12) are coupled to the endrings (16) by connector portions (14), which create a gap between the endrings (16) and the rungs (12). Additionally, the rungs (12) can be positioned over the capacitors (20, 22, 24), and the connector portions (14) can be shaped to offset the position of the rungs (12) relative to the ring segments (16) to which they are coupled to achieve a desire rung position relative to the capacitors (20, 22, 24).

Abstract: A transmission path (13) for transmitting high frequency (RF) signals is disclosed, which comprises a plurality of lead segments (20, 21, 22) which are coupled to one another on one end by a capacitive coupling element (30) and on the other end by an inductive coupling element (31) and which each have an effective length of approximately ?i/4, wherein ?i is the wavelength of a differential mode signal to be transmitted over the path (13). By providing these element (30, 31) in the form of distributed elements which electrically extend over at least a part of adjacent lead segments (20, 21; 21, 22) a very thin transmission path (13) can be realized, which is especially suitable for use with invasive catheters. Furthermore, this path (13) can be guided through RF fields of a magnetic resonance (MR) imaging system because common mode resonances are effectively suppressed.

Abstract: The arrangement (10) is suited for transmitting an informative signal (S1), generated by suitable signal generator (1) at a first electrical site (7a) to a second electrical site (7b). The first electrical site (7a) is electrically connected to the second electrical site (7b) by means of a capacitively coupled transmission line (5a, 5b). In order to enable such capacitively coupled transmission line distributed or lumped capacitors (4a, 4b, 4c, 4d) can be used. The arrangement is connectable to an accessory device (6), which may comprise a spectrometer, a further signal generator, tuning means, etc. The further signal (S2) is generated by the accessory device (6) and transported via the capacitively coupled transmission line (5a, 5b) in a direction from the second electrical site (7b) to the first electrical site (7a). The further signal (S2) can be used for feeding an amplifier (2), or for carrying the signal (S1).

Abstract: A radio frequency coil for magnetic resonance imaging includes an active coil member (70, 701, 170, 270) that defines an imaging volume. The active coil member has a first open end (74) with a first cross-sectional dimension (dactive). A shield coil member (72, 721, 722, 723, 724, 725, 172, 1722, 272) substantially surrounds the active coil member. The shield coil member has a constricted open end (88) arranged proximate to the first open end of the active coil member with a constricted cross-sectional dimension (dconst) that is less than the cross-sectional dimension (dShieid) of the shield coil member. In some embodiments, the radio frequency coil further includes an outer shield coil member (100) that is substantially larger than the shield coil member (72, 721, 722, 723, 724, 725, 172, 1722, 272), and surrounds both the active coil member and the shield coil member.

Abstract: A radio frequency receive coil for receiving a magnetic resonance signal includes a radio frequency antenna. The radio frequency antenna includes one or more electrical conductors (72, 74, 76, 78, 172, 173, 176, 180, 252, 254), at least one of which is a substantially hollow conductor (72, 78, 172, 252, 254). At least one electrical component (100, 110, 110?, 110?, 140, 160, 200) is mounted to be shielded from interfering with the MR signal by disposing it inside the substantially hollow conductor. The at least one electrical component can be, for example, a battery (100, 160, 200), a storage capacitor (140), or coil electronics (110, 110?,110?).

Abstract: A transmission path (13) for transmitting high frequency (RF) signals is disclosed, which comprises a plurality of lead segments (20, 21, 22) which are coupled to one another on one end by a capacitive coupling element (30) and on the other end by an inductive coupling element (31) and which each have an effective length of approximately ?i/4, wherein ?i is the wavelength of a differential mode signal to be transmitted over the path (13). By providing these element (30, 31) in the form of distributed elements which electrically extend over at least a part of adjacent lead segments (20, 21; 21, 22) a very thin transmission path (13) can be realized, which is especially suitable for use with invasive catheters. Furthermore, this path (13) can be guided through RF fields of a magnetic resonance (MR) imaging system because common mode resonances are effectively suppressed.

Abstract: A radio frequency receive coil (50) includes an antenna (52, 52?) that is tuned to a magnetic resonance frequency to detect a magnetic resonance signal. Electronics (54) disposed on or with the antenna (52, 52?) as a unitary structure include compression circuitry (102, 114, 202, 214, 230, 330, 430, 530) that compresses the magnetic resonance signal at a gain controlled by a gain control signal to produce a compressed magnetic resonance signal. The electronics (54) generate a reduced dynamic range representation of the magnetic resonance signal based on the compressed magnetic resonance signal. The reduced dynamic range representation of the magnetic resonance signal is communicated off the receive coil.

Abstract: A radio frequency receive coil for receiving a magnetic resonance signal includes a radio frequency antenna. The radio frequency antenna includes one or more electrical conductors (72, 74, 76, 78, 172, 173, 176, 180, 252, 254), at least one of which is a substantially hollow conductor (72, 78, 172, 252, 254). At least one electrical component (100, 110, 110?, 110?, 140, 160, 200) is mounted to be shielded from interfering with the MR signal by disposing it inside the substantially hollow conductor. The at least one electrical component can be, for example, a battery (100, 160, 200), a storage capacitor (140), or coil electronics (110, 110?,110?).

Abstract: A radio frequency receive coil (50) includes an antenna (52, 52?) that is tuned to a magnetic resonance frequency to detect a magnetic resonance signal. Electronics (54) disposed on or with the antenna (52, 52?) as a unitary structure include compression circuitry (102, 114, 202, 214, 230, 330, 430, 530) that compresses the magnetic resonance signal at a gain controlled by a gain control signal to produce a compressed magnetic resonance signal. The electronics (54) generate a reduced dynamic range representation of the magnetic resonance signal based on the compressed magnetic resonance signal. The reduced dynamic range representation of the magnetic resonance signal is communicated off the receive coil.

Abstract: A radio frequency coil for magnetic resonance imaging includes an active coil member (70, 701, 170, 270) that defines an imaging volume. The active coil member has a first open end (74) with a first cross-sectional dimension (dactive). A shield coil member (72, 721, 722, 723, 724, 725, 172, 1722, 272) substantially surrounds the active coil member. The shield coil member has a constricted open end (88) arranged proximate to the first open end of the active coil member with a constricted cross-sectional dimension (dconst) that is less than the cross-sectional dimension (dShieid) of the shield coil member In some embodiments, the radio frequency coil further includes an outer shield coil member (100) that is substantially larger than the shield coil member (72, 721, 722, 723, 724, 725, 172, 1722, 272), and surrounds both the active coil member and the shield coil member.

Abstract: The arrangement 10 according to the invention is suited for transmitting an informative signal S1, generated by suitable signal generator 1 at a first electrical site 7a to a second electrical site 7b. The first electrical site 7a is electrically connected to the second electrical site 7b by means of a capacitively coupled transmission line 5a, 5b. In order to enable such capacitively coupled transmission line distributed or lumped capacitors 4a, 4b, 4c, 4d can be used. The arrangement is connectable to an accessory device 6, which may comprise a spectrometer, a further signal generator, tuning means, etc. The further signal S2 is conceived to be generated by the accessory device 6 and to be transported via the capacitively coupled transmission line 5a, 5b in a direction from the second electrical site 7b to the first electrical site 7a. The further signal S2 can be used for feeding the amplifier 2, or for carrying the signal S1.

Abstract: The invention relates to a method of and a device for exciting the nuclear magnetization in a limited volume of an object to be examined, utilizing a microcoil (L) which is present in the volume and is attached, for example, to an interventional instrument during the formation of a magnetic resonance image of the object to be examined. The excitation of the nuclear magnetization is performed by at least one RF pulse whose frequency spectrum does not overlap the range of the spin resonance spectrum, so that no nuclear magnetization is excited outside the close range of the microcoil in the object to be examined. The microcoil, however, is provided with an active or passive circuit (for example, it is wired together with at least one capacitance (C) and a non-linear component (D1, D2) so as to form a non-linear resonant circuit) which locally generates an RF signal from the RF pulse.

Abstract: The invention sets forth an RF-safe invasive device which is intended to cooperate with a magnetic resonance imaging apparatus and which contains at least one long conductor for a specific purpose, e.g., the localization of the RF-safe device in an object under test. It is known that in such devices with long conductors during RF transmission of the magnetic resonance apparatus a standing RF wave along the conductors may build up which causes dangerous heating of the device and surrounding tissue. It is the object of the invention to provide a construction applicable to such devices such that the heating of the conductor and surrounding tissue is avoided.

Abstract: The invention relates to an MR method which utilizes a microcoil without connection leads which causes an increase of or a change in phase of an external RF magnetic field in its direct vicinity within an object to be examined. This increase can be used to localize the coil, to image the direct vicinity, or to track the propagation of a liquid flow passing through the direct vicinity.

Abstract: The invention relates to a magnetic resonance (MR) device which is provided with a medical instrument (10) which is to be introduced into an object (1) to be examined, and also with a coil system (11) which is arranged in or on the instrument (10) and includes at least one coil for receiving and/or transmitting an RF signal, to a medical instrument (10) of this kind and also to a method of determining the position of such a medical instrument (10) that can be introduced into an object (1) to be examined. According to the invention the coil system (11) in an MR device of this kind forms a resonant circuit (20) in conjunction with a capacitor (19) and a modulation unit (12) is provided in order to modulate an RF signal coupled into the coil system (11).