Abstract: A magnetic resonance imaging (MRI) array coil system and method for breast imaging are provided. The MRI array coil system includes a top coil portion with two openings configured to receive therethrough objects to be imaged. The MRI array coil system further includes a bottom coil portion having two openings configured to access from sides of the bottom coil portion the objects to be imaged. The top coil portion and bottom coil portion each have a plurality of coil elements configured to provide parallel imaging.

Abstract: A partially parallel acquisition RF coil array for imaging a sample includes at least a first, a second and a third coil adapted to be arranged circumambiently about the sample and to provide both contrast data and spatial phase encoding data.

Abstract: A MRI array coil includes a plurality of first coils in a receive coil array and a plurality of second coils in a transmit coil array. The receive coil array and the transmit coil array are electrically disjoint.

Abstract: A partially parallel acquisition RF coil array for imaging a human head includes at least a first, a second and a third loop coil adapted to be arranged circumambiently about the lower portion of the head; and at least a forth, a fifth and a sixth coil adapted to be conformably arranged about the summit of the head. A partially parallel acquisition RF coil array for imaging a human head includes at least a first, a second, a third and a fourth loop coil adapted to be arranged circumambiently about the lower portion of the head; and at least a first and a second Figure-8 or saddle coil adapted to be conformably arranged about the summit of the head.

Abstract: A partially parallel acquisition RF coil array for imaging a human head having a summit and a lower portion includes at least a first, a second and a third quadrature coil pair adapted to be arranged circumambiently about the lower portion of the head; and at least a forth, a fifth and a sixth quadrature coil pair adapted to be conformably arranged about the summit of the head.

Abstract: A MRI gradient coil set includes a uniplanar Z-gradient coil, a biplanar X-gradient coil, and a biplanar Y-gradient coil. The coil set provides an open Z-axis face.

Abstract: A MRI coil having an axis and a first end and an opposite second end with respect to said axis includes a first ring element at the first end, a second ring element, a third ring element, a fourth ring element at the second end where the first ring element encompasses a smaller area than each of the second, third, and fourth ring elements. The coil also includes a plurality of axial elements connected between the first, second, third and fourth ring elements. The third and fourth ring elements are axially closer than the first and second ring elements.

Abstract: A magnetic resonance apparatus includes a main magnet (12) which generates a main magnetic field through and surrounding an examination region (14). The main magnetic field contains inhomogeneities which affect image quality. A gradient coil assembly (22) generates gradient magnetic fields across the examination region, which contain higher order harmonics causing inhomogeneities in the gradient magnetic field. A multi-axis shim set (23) is selectively excited in order to cancel both the main magnetic and gradient magnetic field inhomogeneities. More particularly, DC currents are applied by a shim coil power supply (25) to cancel the main magnetic field inhomogeneities. AC current pulses are superimposed on the DC currents by the shim coil power supply (25) in order to correct the gradient magnetic field inhomogeneities.

Abstract: A gradient coil assembly (22) generates substantially linear magnetic gradients across the central portion of an examination region (14). The gradient coil assembly (22) includes primary x, y, and z-gradient coils (62, 66, 68) which generate a gradient magnetic field (90) having a non-zero first derivative in and adjacent the examination region. Preferably, the gradient coil assembly (22) includes secondary, shielding x, y, and z coils which generate a magnetic field which substantially cancels, in an area outside a region defined by the shielding coils, a fringe magnetic field generated by the primary gradient coils. The existence of a non-zero first derivative in and adjacent the examination region eliminates aliasing effects attributable to the non-unique gradient field values on either side of a rollover point (82). The non-unique values of the gradient magnetic field adjacent the rollover point caused structure near the rollover point to overlay each other (FIGS. 7B, 8B).

Abstract: A uniplanar gradient coil assembly (40) generates substantially linear gradient magnetic fields through an examination region (14). The gradient coil assembly (40) includes at least a pair of primary uniplanar gradient coil sets (40a, 40b) and a pair of shield coil sets (41a, 41b) which are disposed in an overlapping relationship. One gradient coil set is displaced relative to the other gradient coil set such that the mutual inductance between the two is minimized. Preferably, the coil sets (40a, 40b, 41a, 41b) are symmetric, such that the sweet spot of each coil is coincident with the geometric center of each coil. One primary uniplanar gradient coil set (40a) is a high efficiency, high switching speed coil to enhance performance of ultrafast magnetic resonance sequences, while the second primary uniplanar gradient coil set (40b) is a low efficiency coil which generates a high quality gradient magnetic field, but with slower switching speeds.

Abstract: Methods of designing an active shield for substantially zeroing an electro-magnetic field on one side of a predetermined boundary in open magnetic resonance imaging systems and in open electric systems are provided. The methods include defining a finite length geometry for a primary structure which, in the case of zeroing a magnetic field, carries a first current distribution on its surface. A finite length geometry is also defined for a secondary structure which, in the case of zeroing a magnetic field, carries a second current distribution on its surface. In the case of zeroing an electric field, the current distributions are replaced with charge distributions. A total magnetic or electric field resulting from a combination of the first and second current or charge distributions respectively is constrained such that normal components (in the magnetic field case) or tangential components (in the electric field case) thereof substantially vanish at the surface of one of the primary and secondary structures.

Abstract: A method of designing a shielded gradient coil assemblies (22) for magnetic resonance imaging systems is provided. The method includes generating a first continuous current distribution for a primary coil (60) using an inverse approach. The first continuous current distribution is confined within predetermined finite geometric boundaries of a surface defined by two dimensions and generates a magnetic gradient field across an imaging region (14). The magnetic gradient field constrained to predetermined values at specified spatial locations within the imaging region (14). The current distribution and magnetic field are converted into a stored energy and magnetic field domain where a finite element analysis is performed to generate a second continuous current distribution for a shielding coil (62). The second continuous current distribution is confined within predetermined finite geometric boundaries of a surface surrounding the primary coil (60).

Abstract: A method of designing a shielded gradient coil assemblies (22) with a flared primary coil (60) for magnetic resonance imaging systems is provided. The method includes generating a first continuous current distribution for a primary coil (60) using an inverse approach. The first continuous current distribution is confined within predetermined finite geometric boundaries of a surface defined by three dimensions and generates a magnetic gradient field across an imaging region (14). The magnetic gradient field is constrained to predetermined values at specified spatial locations within the imaging region (14). The current distribution and magnetic field are converted into a stored energy and magnetic field domain where a finite element analysis is performed to generate a second continuous current distribution for a shielding coil (62). The second continuous current distribution is confined within predetermined finite geometric boundaries of a surface surrounding the primary coil (60).

Abstract: A method of designing a shielded gradient coil assembly (22) for magnetic resonance imaging systems is provided. The gradient coil structure comprises two sets of primary gradient coils (60, 62) and a single set of a shielded (screening) coils (64). This configuration is suitable for MR applications utilizing a double duty gradient configuration including a high-efficiency primary coil set that enhances the performance of ultra fast MR sequencing while minimizing the dB/dt and eddy current effects, and including a low-efficiency primary coil set having a high-quality gradient field that is suitable for conventional imaging applications with inherently low dB/dt and eddy current levels. In addition, a minimum inductance/energy algorithm assists in the design of the two primary and the one secondary gradient sets.

Abstract: A superconducting magnetic imaging apparatus includes a vacuum vessel (16) having a central helium reservoir (20) in which superconducting magnetic coil windings (12) are maintained at a superconducting temperature. The vacuum vessel defines an internal bore (22) within which a self-shielded gradient coil assembly (26) and an RF coil (30) are received. The self-shielded coil assembly includes a single former (50) which defines an imaging region (14) within which an imaged portion of a subject is received. Primary x, y, and z-gradient coils (72-76) are positioned over an RF ground screen (70) that is bonded to the former (50). A number of comb-like spacers (84) extend from the former to supporting shield x, y, and z-gradient coils (110-114). The comb-like spacers define passages between the primary and secondary gradient coils which receive inner and outer cooling tubes (90, 92) and shim tray molds (108). The fully assembled gradient coil assembly is potted to form a unitary structure in a single potting step.

Abstract: A magnetic resonance imaging apparatus (10) has a main magnet having a pair of pole faces (16,18) defining an examination region (14). The main magnet generates a main magnetic field (12). A couch (30) suspends a subject within the examination region (14). A uniplanar gradient coil assembly (40) is positioned to one side of the subject. The uniplanar gradient coil assembly (40) generates magnetic field gradients across the examination region (14). The uniplanar gradient coil assembly (40) includes coil loop arrays each residing in a plane which is transverse to the main magnetic field (12). A current supply (42) supplies a electrical current pulses to the coil loop arrays. A radio frequency pulse generator (50) is employed for selectively exciting magnetic resonance of dipoles within the examination region (14). A receiver (54) receives magnetic resonance signals from the resonating dipoles and a reconstruction processor (62) forms an image representation from the magnetic resonance signals received.

Abstract: A magnetic resonance imaging apparatus (10) includes a primary magnet assembly for generating a temporarily constant magnetic field through an examination region (20), a gradient coil assembly for inducing magnetic field gradients across the examination region (20), and a radio frequency coil for receiving resonance signals from the examination region. The gradient coil assembly includes a coil carrying member (22) carrying first (44) and second (46) spaced apart gradient coil portions which are physically separated from each other on the coil carrying member to define at least one azimuthally directed gap (48, 50, 52, 54) extending along the coil carrying member between said first and second gradient coil portions. The first and second coil portions are disposed towards opposite top and bottom sides of the examination region and have internal windings therein for generating gradient magnetic field components along at least two mutually orthogonal axes (X, Y) in the examination region.

Abstract: A magnetic resonance imaging apparatus has a main magnet (20) having opposite first and second poles (22, 24) arranged facing one another to define a subject receiving region (14) therebetween. The main magnet (20) generates a main magnetic field (12) within the subject receiving region (14). The main magnetic field (12) has non-uniformities and radial components at the periphery of the subject receiving region (14). A radio frequency coil (74) is disposed about the subject receiving region (14) to transmit radio frequency signals into the subject receiving region (14) and a receiver receives radio frequency signals therefrom. A shielded thrust balanced bi-planar gradient coil assembly (50) is included. The shielded thrust balanced bi-planar gradient coil assembly (50) has at least one pair of windings for generating substantially linear magnetic gradients across the subject receiving region (14).

Abstract: A localized coil (30) is disposed in the temporally constant magnetic field of a magnetic resonance imaging system. The localized coil is designed in five steps: a static problem formulation step, a static current solution step, a discretization step, a current loop connection step, and a high frequency solution step. One radio frequency coil designed by this process to be carried on a circularly cylindrical former includes two coil sections (60, 62) disposed on opposite sides of the dielectric former. Each of the two coil sections includes a pair of inner loops (64.sub.1, 64.sub.2) disposed symmetrically relative to a z=0 plane of symmetry and a second pair of loops (68.sub.1, 68.sub.2) also disposed symmetrically about the plane of symmetry. To raise self-resonance frequency, the inner and outer loops are connected in parallel. The resonance frequency is fine-tuned with reactive elements (66.sub.1, 66.sub.2).

Abstract: A patient support (40) has lower sections (50a, 50b) of first and second gradient coil assembly portions (42a, 42b) affixed thereto. Upper sections (52a, 52b) of the gradient coil assembly portions are selectively removable from the lower gradient coil assembly sections. The gradient coil assembly sections are mounted such that an interstitial gap is defined therebetween. The gradient coil assembly portions are configured to fit snugly around the patient's torso below the shoulders and around the patient's head, but are too small in diameter to pass around the patient's shoulders. The radio frequency coil (44) has a lower portion (60) disposed below the patient's shoulders and an upper portion (62) removably positionable above the patient's shoulders. The gap between the two gradient coil assembly portions is preferably between 1/2 and 3/4 of a diameter of the gradient coil portions.