A method of designing a pulse sequence for parallel-transmission MRI includes a) for each one of a plurality of subjects, estimating a linear adjustment transformation (L), converting amplitude maps of RF fields generated by respective transmit channels of a MRI apparatus into respective standardized maps; and b) determining RF waveforms (P) minimizing a discrepancy between subject-specific distributions of flip-angles of nuclear spin and a target distribution, averaged over said subjects, the subject-specific distributions corresponding to the flip-angle distributions achieved by applying a superposition of RF fields, each having a temporal profile described by one of said RF waveforms and a spatial amplitude distribution described by a respective standardized map determined for the subject. A method and an apparatus for performing parallel-transmission MRI using such a pulse sequence are provided.

In some aspects, a magnetic system for use in a low-field MRI system. The magnetic system comprises at least one electromagnet configured to, when operated, generate a magnetic field to contribute to a B.sub.0 field for the low-field MRI system, and at least one permanent magnet to produce a magnetic field to contribute to the B.sub.0 field.

Pulse sequences for an MRI apparatus can provide improved quantitative relaxometry in liver and other tissues. Relaxation parameters such as T1rho or T2 (or both at once) can be measured. The pulse sequence can include a magnetization preparation pulse sequence and an acquisition pulse sequence including a fast spin echo (FSE) pulse sequence. Flip angles and echo time for the FSE pulse sequence can be chosen to optimize image quality without affecting the quantification of a relaxation parameter. Additional pulse sequences, e.g., for enhanced blood suppression and/or fat suppression can be incorporated. The acquisition pulse sequence can have a duration that allows data for a single slice image to be acquired during a breath-hold.

A method for measuring oil-water distribution using DNP-MRI, comprising adding a free radical for DNP enhanced NMR signal of a water phase or an oil phase in a sample containing oil and water; performing an MRI experiment on the sample, and collecting an MRI image of the sample without DNP enhancement; applying microwave excitation for DNP-MRI experiment under the same MRI experiment condition as step 2, and collecting an MRI image of the sample after DNP enhancement; and comparing the MRI image after DNP enhancement with the MRI image without DNP enhancement. In the MRI image with DNP enhancement, an area with enhanced MRI signal intensity is a selectively enhanced fluid phase distribution area, and an area without obviously changed MRI signal intensity is a non-selectively enhanced fluid phase distribution area. The method is simple, convenient to operate, short in measurement time, and high in measurement efficiency.

Described here are systems and methods for correcting magnetic resonance data for off-resonance effects arising from the use of a multi-echo echo planar imaging (“EPI”) pulse sequence. Reference data are acquired, from which phase maps are computed in a distorted coordinate space associated with geometric distortions associated with the multi-echo EPI acquisition. Images reconstructed from the magnetic resonance data are demodulated using the distorted phase maps to produce distortion free images of the subject. Advantageously, the systems and methods can be used to reconstruct distortion free images from magnetic resonance data that is otherwise prone to image distortions from off-resonance errors, including data acquired from hyperpolarized nuclear spin species such as hyperpolarized carbon-13.

A method includes: accessing MRI data acquired from a joint area, the MRI data including a series of spatially mapped spectral data points; generating MRI images of the joint area; receiving information encoding a region of interest that encompasses a suspected metal particle deposition area over at least one of the MRI images; constructing magnetic field maps using the MRI data, each representing off-resonance frequency shifts over the joint area; removing a background of off-resonance field inhomogeneity from the magnetic field map such that the region of interest is free from off-resonance field inhomogeneity; identifying clusters from the magnetic field maps with the background of off-resonance field inhomogeneity removed, the clusters defined over a first dimension of offset frequencies and a second dimension of cluster volumes; and computing a quantitative metric by combining information from the identified clusters according to both the first dimension and the second dimension.

This invention relates generally to detection devices having one or more small wells each surrounded by, or in close proximity to, an NMR micro coil, each well containing a liquid sample with magnetic nanoparticles that self-assemble or disperse in the presence of a target analyte, thereby altering the measured NMR properties of the liquid sample. The device may be used, for example, as a portable unit for point of care diagnosis and/or field use, or the device may be implanted for continuous or intermittent monitoring of one or more biological species of interest in a patient.

This invention relates generally to detection devices having one or more small wells each surrounded by, or in close proximity to, an NMR micro coil, each well containing a liquid sample with magnetic nanoparticles that self-assemble or disperse in the presence of a target analyte, thereby altering the measured NMR properties of the liquid sample. The device may be used, for example, as a portable unit for point of care diagnosis and/or field use, or the device may be implanted for continuous or intermittent monitoring of one or more biological species of interest in a patient.

Methods for operating a magnetic resonance apparatus and systems therefrom are provided. A method includes generating, via a coil former surrounding a subject or object of interest and disposed in the magnetic resonance apparatus, a plurality of field modes external to the subject or object, measuring for each of the plurality of external field modes, an associated internal field produced within the subject or object, generating, via the coil former a combination of external modes to produce a target internal field in the subject or object, and measuring nuclear magnetic resonance signals due to the resulting field from the combination to acquire an image or spectrum of the subject or object.

A method can include controlling radio frequency emission circuitry of a nuclear magnetic resonance unit to emit radio frequency energy according to a first set of parameters that comprises a first wait time for an even number of sequence repeats with positive and negative phases and to emit radio frequency energy according to a second set of parameters that includes a second wait time for a single sequence with a single phase, where the second wait time is greater than the first wait time; and acquiring, via antenna circuitry and analog-to-digital conversion circuitry, nuclear magnetic resonance.