General Electric Company

Ge Medical Systems Global Technology Company, LLC

Toshiba America Mri, Inc.

Diasonics, Inc.

James S Tropp

Fraser Robb

Paul David Calderon

Kevin A Derby

Eddy Benjamin Boskamp

Thomas Grafendorfer

K Christine Hawryszko

Victor Taracila

Shreyas S Vasanawala

Daniel K Sodickson

Ralph Eugene Hurd

Patrick L Le Roux

Greig Scott

Daniel Blackburn Vigneron

Napapon Sailasuta

Robert Carl Minnich

Donald McCune

Keerthi Shet

Lucas Guillermo Carvajal

Konstantinos George Karpodinis

Michael A Ohliger

A system and method for generating preamplifier feedback in magnetic resonance imaging (MRI) systems are provided. A preamplifier arrangement for the MRI system includes a plurality of preamplifiers with each of the preamplifiers connected to a different channel of a multi-channel coil array of the MRI system. The preamplifier arrangement further includes a feedback network connected to each of the plurality of preamplifiers with each of the feedback networks configured to generate negative feedback at one or more oscillation frequencies.

System and method providing preamplifier feedback for magnetic resonance imaging

A system for travelling wave MR imaging includes an MR imaging apparatus having a magnet coil assembly having a magnet coil bore extending therethrough, a gradient coil assembly positioned within the magnet coil bore and having a gradient coil bore extending therethrough, and a waveguide positioned within the gradient coil bore. The waveguide has a waveguide bore extending therethrough. A computer is programmed to access a scan sequence comprising an RF pulse sequence and execute the scan sequence. During execution of the scan sequence, the computer is programmed to operate the waveguide in a hybrid mode to transmit an RF pulse of the RF pulse scan sequence as a travelling wave at a frequency lower than a cutoff frequency of a principal mode of the waveguide absent a dielectric core and to acquire MR signals from an imaging subject positioned within the waveguide bore.

System for travelling wave MR imaging at low frequencies and method of making same

A multiple-frequency RF trap and an MRI system including a multiple-frequency RF trap. The multiple-frequency RF trap being tuned to block RF energy at two frequencies.

Multiple-frequency RF trap and MRI system

A dual-frequency coil array for a magnetic resonance imaging (MRI) system is provided. The coil array includes a first coil element having a pair of dual-frequency loop coils and a second coil element having a pair of dual-frequency loop coils. The coil array further includes at least one capacitive mesh configured to decouple the pairs of dual-frequency loop coils of the first and second coil elements.

Dual-frequency coil array for a magnetic resonance imaging (MRI) system

Systems, methods and apparatus are provided through which a compact pod insertable into the rectum for Magnetic Resonance Imaging/Magnetic Resonance Spectroscopy (MRI/MRS) examination of the prostate and containing two receive coils, each connected to transmit blocking and pre-tuned trap circuitry which can be superimposed within the pod in close proximity, can, without either circuit interfering with the other, efficiently gather, for imaging and tissue analysis, radio frequency signals emanating from magnetically disturbed nuclei in prostate tissue.

Systems, methods and apparatus for an endo-rectal receive-only probe

A dome resonator () includes a resonator circuit () that excites and/or receives radio frequency magnetic resonance signals that emanate from a region of interest (). The resonator circuit () includes multiple longitudinal conductive elements () that are coupled at a first end () and a second end () and tapered from the first end () to the second end (). A resonator circuit support () is coupled to and supports the resonator circuit (). A shield () is coupled to the resonator circuit support () and electrically isolates the resonator circuit () from a surrounding environment.

Shielded dome resonator for MR scanning of a cerebrum

A MRI system having a scanning unit adapted to generate a parallel scan includes a substantially cylindrical member defining a scanning bore and a RF coil assembly mounted in the scanning bore. The RF coil assembly includes a TEM surface resonator.

Shielded TEM surface array for parallel imaging

A method and system for designing a radio frequency (RF) coil assembly is disclosed herein. The designing scheme or tool includes determining a self inductance by solving analytically or numerically two-dimensional boundary value problems s. The scheme further includes determining at least one mutual inductance by solving analytically or numerically the two-dimensional boundary value problems. The ratio of the mutual inductance and the self inductance represents a magnetic coefficient of coupling of the RF coil assembly.

Method and apparatus for designing an RF coil assembly

An RF coil assembly for an NMR instrument includes a cylindrical shield disposed concentrically about a central axis and a set of linear conductors disposed concentrically about the central axis and radially inward from the shield. Assembly further includes an annular member positioned to span the gap between the shield and linear conductors. The annular member includes an insulating substrate, a conductive layer over the substrate, and a series of non-conducting gaps through the conductive layer. One or more lumped element capacitors are connected across one or more of the gaps to tune to resonance.

NMR RF coil with improved resonant tuning and field containment

Chemical shift error in proton magnetic resonance spectroscopy is reduced by applying a volume excitation pulse sequence such as PRESS and very selective out-of-volume saturation pulses to limit that volume to a volume-of-interest free of the misregistration errors associated with the excitation sequence. The resulting volume is then only limited by the very small chemical shift misregistration of the very selective saturation pulses.

Magnetic resonance spectroscopic imaging having reduced chemical shift

RF coil apparatus is provided for use in an MR imaging system, wherein the B.sub.0 field is oriented in a specified direction. The apparatus comprises a coil structure positioned in selected relationship with the B.sub.0 field, the coil structure comprising a pair of elongated coil members in spaced-apart parallel relationship, and a selected number of lateral coil members positioned along the elongated coil members in spaced-apart parallel relationship with one another. A number of first capacitive elements, each of a first capacitance, are selectively positioned along the elongated coil members, and a second capacitive element is included in each of the lateral coil members, each of the second capacitive elements being of a second capacitance. A first coupling network operates the coil structure to selectively transmit and receive a first RF field component directed along a first axis which is orthogonal to the B.sub.0 field direction, the first RF field having a frequency determined by a specified relationship between the first and second capacitances. In like manner, a second coupling network operates the coil structure to selectively transmit and receive a second RF field component directed along a second axis which is orthogonal to both the B.sub.0 field direction and the first axis, the second RF field component having a frequency likewise determined by the relationship between the first and second capacitances, the first and second capacitances being respectively selected so that the frequencies thereof are equal.

RF coil apparatus for MR system with lateral B.sub.0 field

In the present invention a method is disclosed to correct the asymmetry in an NMR radio frequency coil of the type that has a pair of conductive loop elements disposed in a spaced apart relation along a common longitudinal axis. The coil has at least eight conductive elements electrically interconnecting the loop elements at point spaced along the periphery of each of the loops. A pair of corrective capacitive elements are placed 45.degree. apart from one another and in series with a pair of the conductive segments which interconnect the loops. The present invention also relates to an NMR radio frequency coil having N-fold symmetry and reduced eddy current.

Method of correcting an asymmetry in an NMR radio frequency coil and an

In a phase encoded chemical shift imaging (CSI) system, phase shifting in k space is used to shift voxels so as to translate them in one or more dimensions so that one or more voxels maximally encloses an object of interest. The position of a structure of interest is located via a 1H 'scout' image, and the Shift Theorem for finite Fourier transforms is applied to shift voxel boundaries in one, two or three dimensions so as to maximally enclose the structure in a minimal number of voxels. Voxel shifts thus may be accomplished computationally by minimal manipulation of the raw data--after the patient has left the imaging facility. The resulting spectral data corresponding to the structure of interest is not as subject to dilution by spectrum of the surrounding tissue.

Fourier shifting of voxel boundaries in MR chemical shift imaging

A hybrid bird cage/Helmholtz RF coil provides a single composite RF coil for MRI spectroscopy involving at least two NMR nuclear species at respectively different RF frequencies. The bird cage portion may be tuned to the lower NMR frequency and coupled to a pair of quadrature-phase input/output ports so as to provide needed extra sensitivity and signal-to-noise ratio. At least one further RF input/output port provides coupling for a second, higher, MNR RF frequency.

Dual-tuned RF coil for MRI spectroscopy

An automated magnetic field shimming process for magnetic resonance spectroscopic imaging (MRSI) uses doubly phase encoded NMR spin echo responses in conjunction with multiple fourier transformation to derive a spectroscopic plot for each voxel in a three-dimensional array of voxels in an image volume (including portions of a living subject) which is to be subsequently subjected to MRSI using NMR FID or spin echo responses. The thus derived hydrogen peak frequency is taken as a measurement of existing static magnetic field intensity within that voxel and adjusted shim coil currents are calculated so as to reduce or minimize nonuniformity of the static magnetic field. A nonexistent pseudo shim coil having an assumed uniform shim contribution may enhance the resulting field homogeneity. The auto shimming procedure may be applied iteratively as required to achieve the predetermined degree of field uniformity.

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Berkeley, CA, United States of America

James S Tropp