Abstract: A system and method are described for MRI excitation pulse design. The system can include a magnetic system that produces a main magnetic field over a portion of a subject for MRI imaging. The system can also include an RF system configured to transmit and receive an RF or B1+ field across at least a target region within the subject. The system may further include a gradient system configured to spatially encode the B1+ field using a gradient waveform. The system may also include a control system, which can be configured to control the RF system in order to generate an RF excitation pulse. The excitation pulse includes freely-shaped RF waveforms, gradient waveforms and, potentially shim array waveforms, selected by penalizing deviation of a flip-angle from a target distribution in order to achieve a target magnetization profile. The method can be applied to 3D and 2D slice-selective excitation and refocusing.

Abstract: A magnet assembly for a portable magnetic resonance imaging (MRI) system includes a former having a plurality of slots and a plurality of magnet blocks configured to create a single-sided permanent magnet. Each of the plurality of magnet blocks are positioned in one of the plurality of slots of the former. The arrangement of the plurality of magnet blocks is configured to optimize homogeneity over a target field of view for brain imaging and to form a cap-shaped configuration to be positioned on a head of a subject.

Abstract: Asymmetric, single-channel radio frequency (“RF”) coils are provided for use with portable or other low-field magnetic resonance imaging (“MRI”) systems. In general, the asymmetric, single-channel RF coils make use of asymmetric, optimized winding configurations in order to reduce B1+ inhomogeneities and to reduce signal sensitivity outside of the desired imaging field-of-view (“FOV”).

Abstract: Electromagnetic interference (“EMI”) is mitigated for portable magnetic resonance imaging (“MRI”) systems using postprocessing interference suppression techniques that make use of EMI detectors external to the MRI system imaging volume to detect EMI signals and remove them from acquired magnetic resonance data. EMI correction models, including static transfer function-based models, dynamic transfer function-based models, correction weight-based models, or parallel imaging kernel-based models can be used to remove the EMI-related artifacts from the magnetic resonance data.

Abstract: A single-sided magnet and magnetic resonance imaging (“MRI”) system are portable and lightweight, enabling use as a point-of care (“POC”) MRI device. The portable MRI system includes a magnet assembly containing layers of magnet blocks, such as rare-earth magnet blocks. The magnet blocks are arranged in concentric rings in each layer, and surround a central aperture extending through the magnet assembly. The central aperture is sized to allow a medical instrument, such as a needle, to pass through the central aperture. The portable MRI system can therefore be used for image guidance in lumbar puncture (“LP”) and other medical procedures.

Abstract: Systems and methods are provided for improving MRI data acquisition efficiency while providing more detailed information with high resolution and isotropic resolution without gaps. Improved data acquisition efficiency may be achieved by implementing a machine learning algorithm with a hardware processor and a memory to estimate imperfections in fast imaging sequences, such as a multi-shot echo planar imaging (MS-EPI) sequence. These imperfections, such as patient motion, physiological noise, and phase variations, may be difficult to model or otherwise estimate using standard physics-based reconstructions.

Abstract: Provided herein are systems and methods for development and use of a perfusion apparatus comprising a biological phantom created from an ex vivo placenta. In some embodiments, a system is provided for perfusing an ex vivo placenta to be imaged using a magnetic resonance imaging (MRI) device, the system comprising a chamber configured to house the ex vivo placenta therein, the chamber including a first partition separating the chamber into a first portion and a second portion, wherein the ex vivo placenta is housed at least partially in the first portion, and at least one first inlet disposed in the second portion for receiving at least one first tube, the at least one first tube being configured to couple at least one first pump to a fetal compartment of the ex vivo placenta when present in the chamber.

Abstract: Systems and methods for designing and manufacturing electromagnetic coils for use with a magnetic resonance imaging (“MRI”) system are described. More particularly, described here are methods for designing and manufacturing gradient coils for producing magnetic field gradients with greater peripheral nerve stimulation (“PNS”) thresholds relative to conventional gradient coils. The gradient coil design is constrained using an oracle penalty that is computed to account for a PNS requirement for the coil. In other applications, the oracle penalty can be used to optimize driving patterns for an electromagnetic stimulation system, such that a target PNS requirement is achieved.

Abstract: Systems and methods are provided for improving MRI data acquisition efficiency while providing more detailed information with high resolution and isotropic resolution without gaps. Improved data acquisition efficiency may be achieved by implementing a machine learning algorithm with a hardware processor and a memory to estimate imperfections in fast imaging sequences, such as a multi-shot echo planar imaging (MS-EPI) sequence. These imperfections, such as patient motion, physiological noise, and phase variations, may be difficult to model or otherwise estimate using standard physics-based reconstructions.

Abstract: A method for assessing peripheral nerve stimulation (PNS) for a coil geometry includes retrieving a PNS Huygens' P-matrix for a body model. The PNS Huygens' P-matrix is defined on a Huygens' surface enclosing the body model. The method further includes generating a coil specific PNS P-matrix for the coil geometry based on at least the PNS Huygens' P-matrix for the body model, determining at least one PNS threshold for the coil geometry based on the coil specific PNS P-matrix, and storing the at least one PNS threshold in a storage device.

Abstract: Systems and methods for magnetic resonance imaging (“MRI”) that address the geometric distortions and blurring common to conventional echo planar imaging (“EPI”) sequences, and that provide new temporal signal evolution information across the EPI readout, are described. Echo planar time-resolved imaging (“EPTI”) schemes are described to implement an accelerated sampling of a hybrid space spanned by the phase encoding dimension and the temporal dimension. In general, each EPTI shot covers a segment of this hybrid space using a zigzag trajectory with an interleaved acceleration in the phase-encoding direction. The hybrid space may be undersampled and a tilted reconstruction kernel used to synthesize additional data samples.

Abstract: A conductive lead apparatus for an implantable medical device includes a first conductor having a first outer diameter and a length, a high-dielectric constant layer having a second outer diameter and disposed around the first outer diameter of the first conductor, and a second conductor disposed around the second outer diameter of the high dielectric constant layer. The first conductor, high dielectric constant layer and the second conductor form a distributed capacitance along the length of the first conductor.

Abstract: Systems and methods for simultaneously acquiring high-resolution images of a subject from multiple different slice locations using magnetic resonance imaging (“MRI”) are described. The present invention overcomes the aforementioned drawbacks by providing method for producing a plurality of images of a subject with a magnetic resonance imaging (“MRI”) system. A radio frequency (RF) excitation field is applied by the MRI system to a portion of a subject that includes a plurality of slice locations. First data are simultaneously acquired from each of the plurality of slice locations by the MRI system.

Abstract: Described here are systems and methods for retrospectively estimating and correcting for rigid-body motion by using a joint optimization technique to jointly solve for motion parameters and the underlying image. This method is implemented for magnetic resonance imaging (“MRI”), but can also be adapted for other imaging modalities.

Abstract: Systems and methods for accelerated diffusion-weighted magnetic resonance imaging using a tilted reconstruction kernel to synthesize unsampled k-space data in phase encoded and point spread function (“PSF”) encoded k-space data are provided. Images reconstructed from the data have reduced B0-related distortions and reduced T2* blurring. In general, data are acquired with systematically optimized undersampling of the PSF and phase encoding subspace. Parallel imaging reconstruction is implemented with a B0 inhomogeneity informed approach to achieve greater than twenty-fold acceleration of the PSF encoding dimension. A tilted reconstruction kernel is used to exploit the correlations in the phase encoding-PSF encoding subspace. Self-navigated phase corrections are computed from the acquired data and used to synthesize the unsampled k-space data.

Abstract: Systems and methods for accelerated magnetic resonance imaging using a tilted reconstruction kernel to synthesize unsampled k-space data in phase encoded and point spread function (“PSF”) encoded k-space data are provided. Images reconstructed from the data have reduced B0-related distortions and reduced T2* blurring. In general, data are acquired with systematically optimized undersampling of the PSF and phase encoding subspace. Parallel imaging reconstruction is implemented with a B0 inhomogeneity informed approach to achieve greater than twenty-fold acceleration of the PSF encoding dimension. A tilted reconstruction kernel is used to exploit the correlations in the phase encoding-PSF encoding subspace.

Abstract: Described here are systems and methods for performing magnetic resonance imaging (“MRI”) using radio frequency (“RF”) phase gradients to provide spatial encoding of magnetic resonance signals rather than the conventional magnetic field gradients. Particularly, the systems and methods described here implement swept RF pulses (e.g., wideband, uniform rate, and smooth transition (“WURST”) RF pulses) and a quadratic phase correction to enable RF phase gradient encoding in inhomogeneous background (B0) magnetic fields.

Abstract: A system and method for performing parallel magnetic resonance imaging (pMRI) process using a low-field magnetic resonance imaging (IfMRI) system includes a substrate configured to follow a contour of a portion of a subject to be imaged by the IfMRI system using a pMRI process. A plurality of coils are coupled to the substrate. Each coil in the plurality of coils has a number of turns and an associated decoupling mechanism selected to operate the plurality of coils to effectuate the pMRI process using the IfMRI system.

Abstract: A magnet assembly for a portable magnetic resonance imaging (MRI) system includes a former having a plurality of slots and a plurality of magnet blocks configured to create a single-sided permanent magnet. Each of the plurality of magnet blocks are positioned in one of the plurality of slots of the former. The arrangement of the plurality of magnet blocks is configured to optimize homogeneity over a target field of view for brain imaging and to form a cap-shaped configuration to be positioned on a head of a subject.

Abstract: Systems and methods for designing parallel transmission radiofrequency (RF) pulses for use in a RF treatment. The methods include selecting a target region in a subject, and providing a plurality of specific absorption rate (SAR) matrices for estimation of SAR at locations within the subject. The methods also include determining a first set of SAR matrices for locations in the target region using the provided SAR matrices, and determining a second set of SAR matrices for locations not in the target region using the provided SAR matrices. The methods further include designing a plurality of RF pulses for achieving a target power deposition in the target region by using the first set of SAR matrices and the second set of SAR matrices in an optimization that determines a set of RF waveforms that produce a target average local SAR using the first set of SAR matrices while minimizing a local SAR and a global SAR using the second set of SAR matrices.