In a method for generation of a homogenization field suitable for homogenization of magnetic resonance data of an examination object, first magnetic resonance data from an examination region of the examination object is provided, a trained function is provided, a homogenization field is extracted by processing the first magnetic resonance data by way of the trained function, and the homogenization field is provided.

In a method for compensating stray magnetic fields in a magnetic resonance imaging system with two or more examination areas: a value for a predefined first magnetic field to be applied in a first examination area, in addition to a basic magnetic field is provided; information defining a predefined sequence control pulse to be applied in a second examination area is provided; a stray magnetic field in the second examination area resulting from application of the first magnetic field in the first examination area is determined; a compensated sequence control pulse for the second examination area is calculated from the predefined sequence control pulse and the determined stray magnetic field; and the compensated sequence control pulse is applied to the second examination area.

Magnetic field sensor, in particular for measuring magnetic noise fields caused by environmental magnetic noise in combination with MRI apparatus, the magnetic field sensor being further provided with field compensation coils assembly and with a compensation circuit driving the field compensation coils assembly to generate a magnetic field compensating the static magnetic field dissipating outside from the static magnetic field generator or from the gantry of the MRI apparatus at the position of the magnetic sensor. A method for operating the magnetic field sensor and a method and a system for compensation magnetic noise caused by environmental noise are also provided. An MRI apparatus is also disclosed comprising such a system and carrying out such a method for compensating magnetic noise fields.

The disclosure relates to techniques for perming chemical exchange saturation transfer (CEST) imaging correction. The present disclosure improves the speed of correcting CEST images.

The invention provides for a magnetic resonance imaging system (100) comprising a radio frequency system (116, 114, 118) configured for acquiring magnetic resonance data (144) from an imaging zone (108). The radio frequency system is configured for sending and receiving radio frequency signals to acquire the magnetic resonance data, wherein the radio frequency system comprises: an elliptical transmission coil (114) configured for generating a B1+ excitation field within the imaging zone; and an active B1 shim coil (118) configured for being placed within the imaging zone, wherein the radio frequency system is configured for suppling radio frequency power to the active B1 shim coil during the generation of the B1+ excitation field by the elliptical transmission coil, wherein the B1 shim coil is configured for shimming the B1+ excitation field within the imaging zone.

The present disclosure discloses a magnetic resonance CEST imaging sequence and device based on a frequency stabilization module. It includes following steps: first, in the frequency stabilization module, exciting a target slice with a small-flip-angle radio frequency pulse, and collecting three lines of non-phase-encoded k-space data; second, obtaining a fine estimated value of a frequency drift of a main magnetic field by calculating a phase difference between the first and second lines of non-phase encoded k-space data; then obtaining a coarse estimated value of the frequency drift of the main magnetic field by calculating a difference between a phase difference between the second and third lines and the phase difference between the first and second lines; then determining the value of the frequency drift of the main magnetic field by comparing a difference between the coarse estimated value and the fine estimated value with a threshold; then adjusting a center frequency of the radio frequency pulse based on the calculation result of the frequency drift of the main magnetic field, to realize a real-time correction of the frequency drift of the main magnetic field; and finally, performing conventional magnetic resonance CEST imaging. The present disclosure realizes the real-time correction of the frequency drift of the main magnetic field during magnetic resonance CEST imaging and ensures effective suppression on fat signals, thereby improving magnetic resonance CEST imaging performance.

Disclosed herein is a medical system (100, 300, 500) comprising a memory (110) storing machine executable instructions (120) and a convolutional neural network (122). The convolutional neural network is configured for receiving an initial Dixon magnetic resonance image (124, 126) as input. The convolutional neural network is configured for identifying one or more water-fat swap regions (128) in the initial Dixon magnetic resonance image. The medical system further comprises a processor (104) for controlling the medical system. Execution of the machine executable instructions causes the processor to: receive (200) the initial Dixon magnetic resonance image; and receive (204) the one or more water-fat swap regions from the convolutional neural network in response to inputting the initial Dixon magnetic resonance image into the convolutional neural network.

A magnetic resonance (MR) image may be created from MR data by receiving the MR data, applying a transform to the MR data, where a result of the applying is an image space representation of the MR data, determining a wrapped phase map of the image space representation of the MR data, obtaining an unwrapped phase map based on the wrapped phase map, scaling the unwrapped phase map into a B0 field map, reconstructing the MR image based on the MR data, correcting the MR image based on the B0 field map, and outputting the MR image. The scaling may be free of accounting for effects on the MR data by artifact sources secondary to B0 field inhomogeneities.

A control device establishes a change in a main magnetic field expected for a respective time instant and based on the established expected change in the main magnetic field, correctively adjusts the main magnetic field and/or a nominal receive frequency of the RF receive coil and/or a transmit frequency for subsequent RF transmit pulses and/or takes the expected change in the main magnetic field into account in the evaluation of the received MR signals. At least for some of the RF transmit pulses, the control device acquires, via a sensor device, a portion of the respective radiofrequency wave supplied to the RF transmit coil. The controller extracts therefrom an oscillation corresponding to a respiratory motion of the patient and based on the variation with time of the extracted oscillation, establishes the change in the main magnetic field expected for the respective time instant.

Disclosed is a medical imaging system (100, 300). The execution of machine executable instructions (120) causes a processor (104) to: receive (200) measured magnetic resonance imaging data (122) descriptive of a first region of interest (307) of a subject (318); receive (202) a B0 map (124), a T1 map (126), a T2 map (128), and a magnetization map (130) each descriptive of a second region of interest (309) of the subject; receive (204) pulse sequence commands (132); calculate (206) a simulated magnetic resonance image (136) of an overlapping region of interest (311) using at least the B0 map, the T1 map, the T2 map, the magnetization map, and the pulse sequence commands as input to a Bloch equation model (134); and reconstruct (208) a corrected magnetic resonance image from the measured magnetic resonance imaging data for the overlapping region of interest by solving an inverse problem. The inverse problem comprises an optimization of a cost function and a regularization term formed from the simulated magnetic resonance image.