Abstract: Some implementations provide a system that includes: a main magnet including a bore and configured to generate a substantially uniform magnetic field in the bore; one or more gradient coils configured to perturb the substantially uniform magnetic field in the bore, wherein perturbing the substantially uniform magnetic field results in a first varying magnetic field outside of the bore; and one or more shielding units located outside of the bore and configured to generate a second varying magnetic field configured to attenuate the first varying magnetic field outside of the bore.

Abstract: A method of data acquisition at a magnetic resonance imaging (MRI) system is provided. The system receives at least a portion of raw data for an image, and detects anomalies in the portion of raw data received. When anomalies are detected, the system can correct those anomalies dynamically, without waiting for a new scan to be ordered. The system can attempt to scan the offending portion of the raw data, either upon detection of the anomaly or at some point during the scan. The system can also correct anomalies using digital correction methods based on expected values. The anomalies can be detected based on variations from thresholds, masks and expected values all of which can be obtained using one of the ongoing scan, previously performed scans and apriori information relating to the type of scan being performed.

Abstract: A method for operating a magnetic resonance imaging (MRI) system that includes: accessing data indicating a first region for imaging a portion of a subject, the portion being placed in a main magnet of the MRI system and the main magnet generating a magnetic field; selecting, from a group of available shimming coils, a first subset of shimming coils arranged and configured such that, when the shimming coils in the first subset are driven, a homogeneity of the magnetic field at the first region is increased; and driving the shimming coils in the selected first subset of shimming coils without driving other shimming coils in the group of available shimming coils such that the homogeneity of the magnetic field at the first region increases relative to the homogeneity of the magnetic field at the first region when the shimming coils of the selected first subset are not driven.

Abstract: The present disclosure provides a method and system of magnetic resonance imaging using a constrained gradient waveform. The constrained gradient waveform is designed to have only predetermined frequencies, for example excluding one or more identified resonant frequencies associated with the MRI system. The application of such a constrained gradient waveform during imaging may aid in reducing noise, vibration and/or heating of the MRI system during imaging.

Abstract: The present disclosure provides a method and system for correcting errors caused by non-linearities in a gradient field profile of a gradient coil in a magnetic resonance imaging (MRI) system. The method includes obtaining a non-linearity tensor at each voxel within the imaging space using a computer model of the gradient coil; correcting motion sensitive encoding using the non-linearity tensor; and generating a corrected image using the corrected motion sensitive encoding.

Abstract: Some implementations provide a system that includes: a main magnet including a bore and configured to generate a substantially uniform magnetic field in the bore; one or more gradient coils configured to perturb the substantially uniform magnetic field in the bore, wherein perturbing the substantially uniform magnetic field results in a first varying magnetic field outside of the bore; and one or more shielding units located outside of the bore and configured to generate a second varying magnetic field configured to attenuate the first varying magnetic field outside of the bore.

Abstract: Some implementations provide a method for safe operation of a magnetic resonance imaging (MRI) system, the method including: determining, at least in part by using a sensor device, location information that indicates a location of an MR-incompatible object relative to the MRI system, the MRI system generating a polarizing magnetic field for imaging a subject; based on the determined location information, determining, by a control unit associated with the MRI system, that the MR-incompatible object poses an operational hazard to the MRI system; and in response to determining that the MR-incompatible object poses an operational hazard to the MRI system, reducing, by the control unit, a strength of the polarizing magnetic field.

Abstract: A method of manufacturing electromagnet coils for use in a magnetic resonance imaging (MRI) system is provided. The electromagnet coils are located in a non-homogeneous external magnetic field. The method comprises forming a coil representation of a coil surface for the electromagnet coils; setting limits for performance metrics for the electromagnet coils including a magnetic field-shape metric and at least one of an external torque metric and an external force metric, the external torque metric and the external force metric based, respectively, at least in part on a torque and a force exerted on the electromagnet coil by the non-homogeneous external magnetic field; forming a performance functional, based on the coil representation and the performance metrics, for generating a current density pattern over the coil surface; optimizing the performance functional and generating a current density pattern based on the optimized performance functional; and obtaining coil windings.

Abstract: Some implementations provide a system that includes: a housing having a bore in which a subject to be image is placed; a main magnet configured to generate a volume of magnetic field within the bore, the volume of magnetic field having inhomogeneity below a defined threshold; one or more gradient coils configured to linearly vary the volume of magnetic field as a function of spatial location; one or more pulse generating coils configured to generate and apply radio frequency (RF) pulses to the volume of magnetic field in sequence to scan the portion of the subject; one or more shim gradient coils configured to perturb a spatial distribution of the linearly varying volume of magnetic field; and a control unit configured to operate the gradient coils, pulse generating coils, and shim gradient coils such that only the user-defined region within the volume of magnetic field is imaged.

Abstract: A magnetic resonance imaging (MRI) system is provided. The system includes a main field magnet generating a main magnetic field B0. Moreover, the system further includes an integrated magnet device. The integrated magnet device has field-shift shield coils and gradient coils. The MRI system further includes a removable insert comprising field-shift shield coils. At least one substrate layer is included in the integrated magnet device to provide mechanical support for the field-shift coils and the gradient coils. Moreover, a cooling mechanism is provided to cool at least some of the magnets.

Abstract: A system and method of acquiring an image at a magnetic resonance imaging (MRI) system is provided. Accordingly, an analog signal based on a pulse sequence and a first gain is obtained. The analog signal is converted into a digitized signal. A potential quantization error is detected in the digitized signal based on a boundary. When the detection is affirmative, a replacement analog signal based on the pulse sequence is received. At least one portion of the replacement analog signal can be based on an adjusted gain. The adjusted gain is a factor of the first gain. The replacement analog signal is digitized into a replacement digitized signal. At least one portion of the replacement digitized signal corresponding to the at least one portion of the replacement analog signal is adjusted based on a reversal of the factor.

Abstract: Some implementations provide a MRI system configured to: access data encoding an input gradient waveform that would otherwise be used on a gradient sub-system of the MRI system to generate a gradient that corresponds to perturbations to the substantially uniform magnetic field; access data encoding a forward impulse response function and an inverse impulse response function, both characterizing a gradient generated from a target impulse input; pre-emphasizing the input gradient waveform by using both the forward impulse response function and the reverse impulse response function; and drive the gradient sub-system using the pre-emphasized gradient waveform such that distortions to the gradient caused by eddy currents within the gradient sub-system are substantially removed while radio-frequency (RF) samples for reconstructing an MRI image are being acquired from a grid that is substantially identical to when gradient sub-system is driven using the input gradient waveform.

Abstract: Some implementations provide a method for safe operation of a magnetic resonance imaging (MRI) system, the method including: determining, at least in part by using a sensor device, location information that indicates a location of an MR-incompatible object relative to the MRI system, the MRI system generating a polarizing magnetic field for imaging a subject; based on the determined location information, determining, by a control unit associated with the MRI system, that the MR-incompatible object poses an operational hazard to the MRI system; and in response to determining that the MR-incompatible object poses an operational hazard to the MRI system, reducing, by the control unit, a strength of the polarizing magnetic field.

Abstract: A system and method of acquiring an image at a magnetic resonance imaging (MRI) system is provided. Accordingly, an analog signal based on a pulse sequence and a first gain is obtained. The analog signal is converted into a digitized signal. A potential quantization error is detected in the digitized signal based on a boundary. When the detection is affirmative, a replacement analog signal based on the pulse sequence is received. At least one portion of the replacement analog signal can be based on an adjusted gain. The adjusted gain is a factor of the first gain. The replacement analog signal is digitized into a replacement digitized signal. At least one portion of the replacement digitized signal corresponding to the at least one portion of the replacement analog signal is adjusted based on a reversal of the factor.

Abstract: The present disclosure provides a method and system of magnetic resonance imaging using a constrained gradient waveform. The constrained gradient waveform is designed to have only predetermined frequencies, for example excluding one or more identified resonant frequencies associated with the MRI system. The application of such a constrained gradient waveform during imaging may aid in reducing noise, vibration and/or heating of the MRI system during imaging.

Abstract: A delta-relaxation magnetic resonance imaging (DREMR) system is provided. The system includes a main field magnet and field shifting coils. A main magnetic field with a strength B0 can be generated using the main filed magnet and the strength B0 of the main magnetic field can be varied through the use of the field-shifting coils. The DREMR system can be used to perform signal acquisition based on a pulse sequence for acquiring at least one of T2*-weighted signals imaging; MR spectroscopy signals; saturation imaging signals and MR signals for fingerprinting. The MR signal acquisition can be augmented by varying the strength B0 of the main magnetic field for at least a portion of the pulse sequence used to acquire the MR signal.

Abstract: Described here are systems and methods for mitigating or otherwise removing the effects of short-term magnetic field instabilities caused by oscillations of the cold head in a cryogen-free magnet system used for magnetic resonance systems, such as magnetic resonance imaging (“MRI”) systems, nuclear magnetic resonance (“NMR”) systems, or the like.

Abstract: Systems and methods for magnetic field-dependent relaxometry using magnetic resonance imaging (“MRI”] are provided. Relaxation parameters, including longitudinal relaxation time (“T1”) and transverse relaxation time (“T2”), are estimated from magnetic resonance signal data acquired at multiple different magnetic field strengths using the same MRI system. By measuring these relaxation parameters as a function of magnetic field strength, T1 dispersion data, T2 dispersion data, or both, are generated. Based on this dispersion data, quantitative physiological parameters can be estimated. As one example, iron content can be estimated from T2 dispersion data.

Abstract: Some implementations provide a MRI system configured to: access data encoding an input gradient waveform that would otherwise be used on a gradient sub-system of the MRI system to generate a gradient that corresponds to perturbations to the substantially uniform magnetic field; access data encoding a forward impulse response function and an inverse impulse response function, both characterizing a gradient generated from a target impulse input; pre-emphasizing the input gradient waveform by using both the forward impulse response function and the reverse impulse response function; and drive the gradient sub-system using the pre-emphasized gradient waveform such that distortions to the gradient caused by eddy currents within the gradient sub-system are substantially removed while radio-frequency (RF) samples for reconstructing an MRI image are being acquired from a grid that is substantially identical to when gradient sub-system is driven using the input gradient waveform.

Abstract: A magnetic resonance imaging (MRI) system is provided. The system includes a main field magnet generating a main magnetic field B0. Moreover, the system further includes an integrated magnet device. The integrated magnet device has field-shift coils including primary field-shift coils and field-shift shield coils, the primary field shift coils being placed closer to an object to be imaged within the imaging volume than the field-shift shield coils. The gradient coils are placed between the primary field-shift coils and field-shift shield coils. At least one substrate layer is included to provide mechanical support for the field-shift coils and the gradient coils.