Embodiments of the present application provide a magnetic resonance system and a transmission apparatus, a transmission method, and a pre-scanning method. The apparatus includes: a signal output unit used to generate and output a pulse signal; a radio-frequency amplifier used to amplify the pulse signal; a signal processing unit used to transmit, to a transmit coil of the magnetic resonance system, the signal amplified by the radio-frequency amplifier, receive and adjust a phase of the feedback signal, and output the phase-adjusted feedback signal to the signal output unit; and a determination unit used to acquire amplitude values of the feedback signal at different phases, and determine a forward power and/or a reverse power according to the amplitude values of the feedback signal at the different phases.

An MRI system RF transmit antenna arrangement 3 including an antenna 5 including a length of coaxial cable 51 with an electrically conductive core 52 and an electrically conductive outer shield 53 through which the core runs, with the core having a feed point 52a arranged for electrical connection to an RF source and at least one break 53a being provided in the electrically conductive outer shield partway along the length of coaxial cable so as to divide the electrically conductive outer shield 53 into at least two axially spaced shield portions such that at least one of the shield portions acts as a radiating element when an RF source is connected to the feed point 52a.

An apparatus and method for improved S/N measurements useful for electron paramagnetic resonance imaging in situ and in vivo, using high-isolation transmit/receive surface coils and temporally spaced pulses of RF energy (e.g., in some embodiments, a RF pi pulse) having an amplitude sufficient to rotate the magnetization by 180 degrees followed after varied delays, by a second RF pulse having an amplitude half that of the initial pulse to rotate the magnetization by, e.g., 90 degrees (a pi/2 pulse), to the plane orthogonal to the static field where it evolves for a short time. Then a third RF pi pulse sufficient to rotate the magnetization by, e.g., 180 degrees, forms an echo (in some embodiments, the second and third pulses are from the same signal as the first pulse but are phase shifted by 0, 90, 180, or 270 degrees to reduce signal artifact), to image human body.

Systems and methods for the delivery of linear accelerator radiotherapy in conjunction with magnetic resonance imaging in which components of a linear accelerator may be placed in shielding containers around a gantry, may be connected with RF waveguides, and may employ various systems and methods for magnetic and radio frequency shielding.

The present disclosure provides a magnetic resonance imaging (MRI) radio frequency (RF) coil assembly. The MRI RF coil assembly may include one or more coils and one or more control circuits. Each of the one or more coils may include a first end and a second end. Each of the one or more control circuits may electrically connect the first end and the second end of one of the one or more coil. Each of the one or more control circuits may be configured to adjust an operation of the coil that is electrically connected with the control circuit based on an input control signal. The one or more control circuits may be located at different regions.

A method for operating an MR system with a gradient pulse amplifier unit that has an end stage connected to a gradient coil with switching elements is provided. The gradient pulse amplifier unit includes a modulator for actuating the switching elements, and lockout switches interconnected in signal paths from the modulator to the switching elements. The gradient pulse amplifier unit includes feeder circuit breakers interconnected in at least some signal paths from the modulator to the switching elements. The circuit breakers are connected in the associated signal paths downstream of the lockout switches. A gradstop unit configured to receive at least one shut-off signal and actuate the lockout switches and the feeder circuit breakers. When the gradstop unit receives a shut-off signal, the gradstop unit actuates the lockout switches to lock out and the feeder circuit breakers to output an actuation signal to the switching elements.

Certain aspects of the present disclosure provide methods and apparatus for closed-loop control of a system using one or more electron paramagnetic resonance (EPR) sensors located on-site. With such EPR sensors, a change can be applied to the system, the EPR sensors can measure the effect(s) of the change, and then adjustments can be made in real-time. This feedback process may be repeated continuously to control the system.

Provided in an embodiment of the present application are a magnetic resonance imaging system and a transmission apparatus and a transmission method. The method comprises: generating and outputting a pulse signal by a transmission controller; amplifying the pulse signal by a radio-frequency amplifier; transmitting, by a signal processor, the signal amplified by the radio-frequency amplifier to a transmit coil of the magnetic resonance imaging system; and generating frequency offset lookup information for bandwidth compensation of the entire transmission apparatus according to bandwidth data of the transmission controller, the radio-frequency amplifier, and the signal processor; wherein the frequency offset lookup information is used to control the transmission controller to generate output power. Thus, the method can use the frequency offset lookup information to perform digital pre-distortion processing of a power amplifier, and can also improve the bandwidth performance of the entire transmission apparatus and improve the quality of magnetic resonance images.

The present disclosure provides a method for using a magnetic resonance system to measure magnetization data from a region of interest in a subject having a spin system that includes at least a first labile spin species and a second labile spin species experiencing chemical exchange. The method includes applying periodic radiofrequency irradiation to the spin system using a frequency swept pulse sequence having frequency and amplitude modulation functions, wherein sweeping a frequency of the RF irradiation together with amplitude modulation generates a magnetic field component having an effective field. The method further includes generating off resonance side bands in a frequency domain positioned adjacent the resonant frequency of the first labile spin species or the second labile spin species by applying the periodic RF irradiation to induce the instantaneous flip of the effective field with periodicity of RF irradiation tuned to the chemical shift difference of the exchanging sites.

The present disclosure provides a magnetic resonance imaging (MRI) radio frequency (RF) coil assembly. The MRI RF coil assembly may include one or more coils and one or more control circuits. Each of the one or more coils may include a first end and a second end. Each of the one or more control circuits may electrically connect the first end and the second end of one of the one or more coil. Each of the one or more control circuits may be configured to adjust an operation of the coil that is electrically connected with the control circuit based on an input control signal. The one or more control circuits may be located at different regions.