Abstract: Embodiments relate to multi-turn magnetic resonance imaging (MRI) radio frequency (RF) coil arrays employing ring decoupling, and MRI apparatuses employing such coil arrays. One example embodiment comprises: four or more RF coil elements that enclose a cylindrical axis, wherein each RF coil element comprises a first capacitor of that RF coil element and a loop comprising at least two turns; and a ring structure that facilitates decoupling of the RF coil elements, wherein each RF coil element is adjacent to two neighboring RF coil elements and is non-adjacent to one or more other coil elements, wherein each RF coil element has a shared side in common with the ring structure, wherein the shared side comprises a second capacitor of that RF coil element with a capacitance selected to mitigate inductive coupling between that RF coil element and non-adjacent RF coil elements.

Abstract: Embodiments relate to birdcage coils with in-plane open RF shielding capable of operating at 7T and higher field strength. One example embodiment comprises a first birdcage circuit and second birdcage circuit, each comprising two rings, N rungs that electrically connect the two rings of that circuit, a plurality of capacitors in the first birdcage circuit to form a first birdcage coil, and an optional plurality of capacitors in the second birdcage circuit to form a second birdcage coil when included or a non-resonant RF shield when omitted, wherein the first birdcage circuit is electrically isolated from the second birdcage circuit, wherein the first birdcage circuit and the second birdcage circuit have a common cylindrical axis, and wherein the N rungs of the second birdcage circuit are azimuthally rotated through a first angle relative to the N rungs of the first birdcage circuit.

Abstract: An example magnetic resonance imaging (MRI) radio frequency (RF) coil array comprises: at least one row of RF coil elements arranged radially around a cylindrical axis, wherein each row comprises: at least four RF coil elements circumferentially enclosing the cylindrical axis, wherein each RF coil element of that row is configured to operate in a Tx mode and in a Rx mode, wherein, in the Rx mode, each RF coil element of that row is tuned to a working frequency of the MRI RF coil array, and wherein, in the Tx mode, each RF coil element of that row is tuned to an additional frequency that is different than the working frequency, wherein the additional frequency is such that, a mode frequency of a selected mode resulting from coupling among the RF coil elements of that row is at the working frequency.

Abstract: Methods and other embodiments control a member of a plurality of MRI transmit (Tx)/receive (Rx) coil array elements to operate in a resonant Tx mode or in a non-resonant Tx mode. The member of the plurality of MRI Tx/Rx coil array elements, upon resonating with a primary coil at a working frequency, generates a local amplified Tx field based on an induced current in the member of the plurality of MRI Tx/Rx coil array elements. The member of the plurality of MRI Tx/Rx coil array elements includes at least one magnitude/phase control circuit connected in parallel. Upon detecting that the member of the plurality of MRI Tx/Rx coil array elements is operating in resonant Tx mode, embodiments randomly control a member of the at least one magnitude/phase control circuit to vary the magnitude or phase of the local amplified Tx field over a range of magnitudes or phases.

Abstract: An MRI RF coil array for use in a multi-channel MRI system, comprising a plurality of coils arranged in a M by N array, the number of columns corresponding with the number of channels in the MRI system. Columns are aligned with the B0 field. The plurality of coils are configured as a plurality of combined coils, corresponding with the number of columns, comprising a coil in a first row of the array connected with a coil in each of the remaining rows. The column position of each coil of a combined coil is distinct from the column position of each other coil of the combined coil. Coils of a combined coil are disjoint from the coils of each, other, combined coil. A combined coil is configured to connect with a corresponding member of the plurality of Rx channels, and is decoupled from each, other combined coil.

Abstract: Example magnetic resonance imaging (MRI) radio frequency (RF) coils employ flexible coaxial cable. An MRI RF coil may include an LC circuit and an integrated decoupling circuit. The LC circuit includes one or more flexible coaxial cables having a first end and a second end, the one or more flexible coaxial cables having an inner conductor, an outer conductor, and a dielectric spacer disposed between the inner conductor and the outer conductor, where the outer conductor of the coaxial cable is not continuous between the first end and the second end at a first location. The integrated decoupling circuit may include a PIN diode and a tunable element. The tunable element may be tunable with respect to resistance, capacitance, or inductance, and thus may control, at least in part, the frequency at which the LC circuit resonates during RF transmission, or an impedance at the first location.

Abstract: Embodiments relate to magnetic resonance imaging (MRI) radio frequency (RF) coil arrays having reduced coupling via hidden transmission lines. One example embodiment comprises a MRI RF coil array comprising: a first RF coil element coupled to a first output transmission cable (e.g., coaxial) that is configured to carry a first signal that is associated with the first RF coil element; a second RF coil element coupled to a second output transmission cable that is configured to carry a second signal that is associated with the second RF coil element, wherein the second RF coil element comprises a first portion of the first output transmission cable; and a first balun configured to reduce coupling associated with the first signal, wherein the first balun is arranged between the first RF coil element and the second RF coil element. Additional coil elements can be similarly combined in embodiments.

Abstract: A single-layer magnetic resonance imaging (MRI) radio frequency (RF) coil array configured to operate in a transmit (Tx) mode or in a receive (Rx) mode comprises at least one single-layer MRI RF coil array element configured to provide integrated B0 field shimming. The at least one single-layer MRI RF coil array element includes a resonant LC coil, a matching Tx/Rx switch circuit, a magnitude/phase control component, and a preamplifier. The LC coil, upon resonating with a primary coil at the working frequency, generates a local amplified Tx field based on an induced current in the LC coil. The magnitude/phase control component is configured to independently adjust a magnitude or a phase of the induced current. The at least one single-layer MRI RF coil element may include a Tx field monitoring component configured to monitor the strength or phase of the local amplified Tx field.

Abstract: Example embodiments include a radio frequency (RF) transmit system for a digital RF current source, the system including a magnetic resonance imaging (MRI) system control console operably connected to at least one digital RF current source amplifier. The at least one digital RF current source amplifier is operably connected to an RF transmission coil. The MRI system control console provides a digital control signal to the at least one digital RF current source amplifier. The MRI system control console provides a master RF current source clock signal to the at least one digital RF current source amplifier. The digital RF current source amplifier provides an alternating current to the RF transmission coil.

Abstract: An example magnetic resonance imaging (MRI) coil base apparatus for use with interchangeable attachable and detachable coil attachments is described. The coil base apparatus electrically and mechanically couples to different MRI coil attachments designed for imaging different body parts (e.g., ankles, knees, wrists, elbows, shoulders). The MRI coil base apparatus includes elements (e.g., channel, pre-amplifier, mixer, feed circuit, decoupling circuit) for controlling the coil attachment to transmit radio frequency (RF) energy that produces nuclear magnetic resonance (NMR) in an object exposed to the RF energy. The coil attachment includes elements that transmit the RF energy and a copper trace that receives resulting NMR signals. The coil base apparatus may include a slide apparatus for repositioning the coil attachment in one axis when the coil attachment is coupled to the coil base apparatus or a pivot apparatus for rotating the coil attachment when it is coupled to the coil base apparatus.

Abstract: A magnetic resonance imaging (MRI) radio frequency (RF) coil array configured to operate in a transmit (Tx) mode or in a receive (Rx) mode, the MRI RF coil array comprising at least one single-layer RF coil element. The at least one RF coil element includes a resonant LC coil, a matching Tx/Rx switch circuit, and a preamplifier. The matching and Tx/Rx switch circuit, when operating in Tx mode, electrically isolates the LC coil from the preamplifier upon the LC coil resonating with a primary coil at the primary coil's working frequency. The LC coil, upon resonating with the primary coil at the working frequency, generates a local amplified Tx field based on an induced current in the LC coil. A magnitude or a phase of the induced current is independently adjustable. The matching and Tx/Rx switch circuit, when in Rx mode, electrically connects the LC coil with the preamplifier.

Abstract: Example apparatus and magnetic resonance imaging (MRI) radio frequency (RF) coils concern controlling current magnitude at different sections in one MRI RF coil. In one embodiment, an MRI RF coil comprises a plurality of loop coils configured to transmit or receive an RF signal. A member of the plurality of loop coils comprises an inductor and at least one capacitor. The MRI RF coil further comprises at least one coaxial transmission line that electrically couple in series a first member of the plurality of loop coils with a second, different member of the plurality of loop coils. The at least one coaxial transmission line has a length that is one-quarter wavelength (?/4) of the RF signal, or an odd integer multiple of ?/4 of the RF signal.

Abstract: A magnetic resonance imaging (MRI) radio frequency (RF) coil comprising an LC circuit including at least one series capacitor, and a decoupling circuit connected in parallel to the LC circuit. The decoupling circuit is configured to decouple the MRI RF coil from one or more other MRI RF coils using passive decoupling upon the production of an induced voltage in the decoupling circuit, or to actively decouple the MRI RF coil from one or more other MRI RF coils upon the insertion of a DC bias into the decoupling circuit. The decoupling circuit includes a pair of fast switching PIN diodes including a first PIN diode connected antiparallel with a second PIN diode, the second PIN diode connected in series with a first capacitor. The decoupling circuit further includes an inductor connected in series with the pair of fast switching PIN diodes and the capacitor.

Abstract: Apparatus associated with improved magnetic resonance imaging (MRI) guided needle biopsy procedures (e.g., breast needle biopsy) are described. One example apparatus includes a support structure configured to support a patient in a face-down prone position where a breast of the patient is positioned in a first free hanging pre-imaging position. The example apparatus includes an immobilization structure configured to reposition the breast into an immobilized position suitable for MRI and for medical instrument access. The immobilization structure may include a removable biopsy plate, a removable side coil, a pressure plate, and MRI coils. The MRI coils are configured to be repositioned from a first position associated with the free hanging pre-imaging position to a second position associated with the immobilized position to facilitate improving the signal to noise ratio associated with signal received from the breast through the MRI coils.

Abstract: Example magnetic resonance imaging (MRI) radio frequency (RF) coils are described. An MRI RF coil may include an LC circuit and an integrated decoupling circuit. The integrated decoupling circuit may include a wire or other conductor that is connected to the LC circuit and that is positioned within a defined distance of the LC circuit. The integrated decoupling circuit may include a PIN diode and a tunable element. The tunable element may be tunable with respect to resistance, capacitance, or inductance, and thus may control, at least in part, the frequency at which the LC circuit resonates during RF transmission. The example MRI RF coil has more than one point of high impedance, which facilitates reducing heating and operational issues associated with conventional coils.

Abstract: Example magnetic resonance imaging (MRI) radio frequency (RF) coils are described. An MRI RF coil may include a first terminal and a second terminal that are connected by a coaxial cable. Rather than rely exclusively on two terminal passive components (e.g., resistor, inductor, capacitor), example coax MRI RF coils rely on the capacitance that can be created in the coax cable between the inner conductor and the outer conductor. The capacitance of the coil may be controlled by selectively disrupting (e.g., cutting, stripping) the outer conductor, the inner conductor, or the dielectric material disposed between the inner and outer conductor.

Abstract: An electrically-controlled failsafe switch is included in an MRI transmit-and-receive RF coil assembly so as to protect it from induced RF currents in the event it is disconnected from an MRI system, but inadvertently left linked to strong MRI RF fields during imaging procedures using other RF coils.