Magnetic resonance imaging (MRI) coil with integrated decoupling
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.
1. A magnetic resonance imaging (MRI) radio frequency (RF) coil, comprising:
an LC circuit, and
an integrated decoupling circuit attached to the LC circuit and positioned at a fixed, predetermined distance from the LC circuit,
where the integrated decoupling circuit includes one or more conductors, one or more capacitors, a PIN diode, and a tunable element, where the tunable element controls, at least in part, a frequency at which the MRI RF coil transmits RF energy, and where the PIN diode selectively electrically isolates the integrated decoupling circuit from the LC circuit; and
where elements of the LC circuit and elements of the integrated decoupling circuit produce a reactance through the conductor of the integrated decoupling circuit, where the reactance is sufficient to prevent self-cancelling between elements of the LC circuit and elements of the integrated decoupling circuit.
2. The MRI RF coil of claim 1 , where the integrated decoupling circuit decouples the MRI RF coil from one or more other MRI RF coils.
3. The MRI RF coil of claim 1 , where the tunable element is tunable with respect to resistance that controls, at least in part, the frequency at which the LC circuit resonates during RF transmission.
4. The MRI RF coil of claim 1 , where the tunable element is tunable with respect to capacitance that controls, at least in part, the frequency at which the LC circuit resonates during RF transmission.
5. The MRI RF coil of claim 1 , where the tunable element is tunable with respect to inductance that that controls, at least in part, the frequency at which the LC circuit resonates during RF transmission.
6. The MRI RF coil of claim 1 , where the fixed, pre-determined distance is within one millimeter.
7. The MRI RF coil of claim 1 , where the fixed, pre-determined distance is within one tenth of one millimeter.
8. The MRI RF coil of claim 1 , where elements of the LC circuit and elements of the integrated decoupling circuit produce two or more points of high impedance in the MRI RF coil, where the high impedance is at least 4 kΩ.
9. The MRI RF coil of claim 1 , where elements of the LC circuit and elements of the integrated decoupling circuit produce three or more points of high impedance in the MRI RF coil, where the high impedance is at least 4 kΩ.
10. The MRI RF coil of claim 1 , where elements of the LC circuit and elements of the integrated decoupling circuit produce two or more points of high impedance in the MRI RF coil, where the high impedance is at least 1 kΩ.
11. The MRI RF coil of claim 1 , where elements of the LC circuit and elements of the integrated decoupling circuit produce three or more points of high impedance in the MRI RF coil, where the high impedance is at least 1 kΩ.
12. The MRI RF coil of claim 1 , where the PIN diode is driven to a first state when the MRI RF coil is transmitting RF energy, where the first state blocks current from flowing through the LC circuit.
13. The MRI RF coil of claim 12 , where the PIN diode is driven to a second different state when the MRI RF coil is not transmitting RF energy, where the second state allows current to flow through the LC circuit.
14. The MRI RF coil of claim 1 , where the PIN diode and tunable element are connected in series in the integrated decoupling circuit.
15. A magnetic resonance imaging (MRI) radio frequency (RF) coil, comprising:
an LC circuit, and
an integrated decoupling circuit attached to the LC circuit and positioned at a fixed, predetermined distance from the LC circuit,
where the integrated decoupling circuit includes one or more conductors, a PIN diode, one or more capacitors, and a tunable element, where the PIN diode and tunable element are connected in series in the integrated decoupling circuit,
where the PIN diode selectively electrically isolates the integrated decoupling circuit from the LC circuit,
where the PIN diode is driven to a first state when the MRI RF coil is transmitting RF energy, where the first state blocks current from flowing through the LC circuit, and where the PIN diode is driven to a second different state when the MRI RF coil is not transmitting RF energy, where the second state allows current to flow through the LC circuit,
where the integrated decoupling circuit decouples the MRI RF coil from one or more other MRI RF coils,
where the tunable element is tunable with respect to resistance, capacitance, or inductance, where the resistance, capacitance and inductance control, at least in part, the frequency at which the LC circuit resonates during RF transmission,
where elements of the LC circuit and elements of the integrated decoupling circuit produce a reactance through the conductor of the integrated decoupling circuit, where the reactance is sufficient to prevent self-cancelling between elements of the LC circuit and elements of the integrated decoupling circuit,
where elements of the LC circuit and elements of the integrated decoupling circuit produce two or more points of high impedance in the MRI RF coil, where the high impedance is at least 1 kΩ.
16. An MRI apparatus, comprising:
a controller, and
an RF coil operably connected to the controller,
where the controller provides the RF coil with a current, a voltage, or a control signal that causes the RF coil to resonate at a desired transmission frequency, and
where the coil comprises:
an LC circuit, and
an integrated decoupling circuit attached to the LC circuit, where the integrated decoupling circuit decouples the RF coil from one or more other RF coils associated with the MRI apparatus,
where the integrated decoupling circuit includes one or more conductors, one or more capacitors, a PIN diode, and a tunable element,
where the tunable element controls, at least in part, a frequency at which the RF coil transmits RF energy,
where the PIN diode selectively electrically isolates the integrated decoupling circuit from the LC circuit;
where elements of the LC circuit and elements of the integrated decoupling circuit produce a reactance through the conductor of the integrated decoupling circuit, where the reactance is sufficient to prevent self-cancelling between elements of the LC circuit and elements of the integrated decoupling circuit, and
where the PIN diode is driven to a first state when the RF coil is transmitting RF energy, where the first state blocks current from flowing through the LC circuit, and where the PIN diode is driven to a second different state when the RF coil is not transmitting RF energy, where the second state allows current to flow through the LC circuit.
17. The MRI apparatus of claim 16 , where the tunable element is tunable with respect to resistance, capacitance, or inductance, where the resistance, capacitance and inductance control, at least in part, the frequency at which the LC circuit resonates during RF transmission.
18. The MRI apparatus of claim 17 , where elements of the LC circuit and elements of the integrated decoupling circuit produce two or more points of high impedance in the RF coil, where the high impedance is at least 1 kΩ.