Modulating magnetic resonance imaging transmit field in magnetic resonance fingerprinting using single layer transmit/receive radio frequency coil

A magnetic resonance imaging (MRI) radio frequency (RF) coil array configured to operate in a magnetic resonance fingerprinting (MRF) system, the MRI RF coil array comprising:

• a single-layer MRI RF coil element configured to operate in an MRF transmit (Tx) mode or in a receive (Rx) mode, where the single-layer MRI RF coil element includes at least one capacitor;
• a first MRF magnitude/phase randomization path connected to the single-layer MRI RF coil element, where the first MRF magnitude/phase randomization path, upon the single-layer MRI RF coil element operating in the MRF transmit mode, varies a magnitude and/or phase of an induced current in the single-layer MRI RF coil element;
• and
• at least one additional MRF magnitude/phase randomization circuit path, where a first member of the at least one additional MRF magnitude/phase randomization circuit path is connected in parallel with the first MRF magnitude/phase randomization path and with at least a second member of the at least one additional MRF magnitude/phase randomization circuit path, where the first member of the at least one additional MRF magnitude/phase randomization circuit path, upon the single-layer MRI RF coil element operating in the MRF transmit mode, varies the magnitude and/or phase of the induced current in the single-layer MRI RF coil element
• where the first MRF magnitude/phase randomization path comprises a randomness circuit and a magnitude/phase control circuit that are independent of each other, where the randomness circuit is configured to generate a random control signal that switches randomly between different control states, and where the magnitude/phase control circuit is configured to change the magnitude and/or phase of the induced current in response to state changes of the random control signal.

A magnetic resonance fingerprinting (MRF) apparatus, comprising:

• a controller;
• a primary coil connected to the controller;
• and
• a single-layer MRI radio frequency (RF) coil array operably connected to the controller, where the single-layer MRI RF coil array includes at least one RF transmit (Tx)/receive (Rx) coil configured to operate in a resonant Tx mode or in a non-resonant Rx mode;
• where the controller provides the primary coil with a current, a voltage, or a control signal, and
• where the at least one RF Tx/Rx coil comprises:
• an LC coil;
• a matching and transmit (Tx)/receive (Rx) switch circuit;
• a preamplifier;
• a plurality of magnitude/phase randomization circuits connected in parallel to the LC coil at a first point of the LC coil and a second point of the LC coil;
• where the LC coil includes at least one inductor and at least one capacitor, where the at least one inductor and the at least one capacitor resonate at a first frequency;
• where the matching and Tx/Rx switch circuit, when the at least one RF Tx/Rx coil operates in the resonant Tx mode, electrically isolates the LC coil from the preamplifier upon the LC coil resonating with the primary coil at a working frequency of the primary coil, where the LC coil, upon resonating with the primary coil at the working frequency of the primary coil, generates a local amplified Tx field based on an induced current in the LC coil, where the induced current is induced in the LC coil by mutual inductance with the primary coil, and where a magnitude of the induced current or a phase of the induced current are configured to be varied over a range of magnitudes or phases respectively;
• where the matching and Tx/Rx switch circuit, when the at least one RF Tx/Rx coil operates in the non-resonant Rx mode, electrically connects the LC coil with the preamplifier;
• where the plurality of magnitude/phase randomization circuits, upon the at least one RF Tx/Rx coil operating in the resonant Tx mode, varies the magnitude of the induced current or the phase of the induced current over the range of magnitudes or phases, respectively, by adjusting coil loss resistance of the LC coil and/or a resonant frequency of the LC coil;
• and
• where the primary coil is distinct from the LC coil and the plurality of magnitude/phase randomization circuits.

A method for modulating a magnetic resonance imaging (MRI) transmit field, the method comprising:

• controlling 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 Rx mode, where the member of the plurality of MRI Tx/Rx coil array elements, upon resonating with a primary coil at a working frequency of the primary coil, generates a local amplified Tx field based on an induced current in the member of the plurality of MRI Tx/Rx coil array elements, where the member of the plurality of MRI Tx/Rx coil array elements includes a single-layer coil element and at least one magnitude/phase control circuit, where the at least one magnitude/phase control circuit is connected in parallel and is connected to the single-layer coil element at a first point of the single-layer coil element and a second point of the single-layer coil element;
• upon detecting that the member of the plurality of MRI Tx/Rx coil array elements is operating in the resonant Tx mode:
• randomly controlling a member of the at least one magnitude/phase control circuit to vary a magnitude or phase of the induced current in the member of the plurality of MRI Tx/Rx coil array elements over a range of magnitudes or phases respectively, where the magnitude or phase is varied by adjusting coil loss resistance of the member of the plurality of MRI Tx/Rx coil array elements and/or a resonant frequency of the member of the plurality of MRI Tx/Rx coil array elements;
• where the primary coil is distinct from the member of the plurality of MRI Tx/Rx coil array elements and the at least one magnitude/phase control circuit.