210 results about "Surface coil" patented technology

A system and method for using magnetic resonance imaging to increase the accuracy of electrophysiologic procedures is disclosed. The system in its preferred embodiment provides an invasive combined electrophysiology and imaging antenna catheter which includes an RF antenna for receiving magnetic resonance signals and diagnostic electrodes for receiving electrical potentials. The combined electrophysiology and imaging antenna catheter is used in combination with a magnetic resonance imaging scanner to guide and provide visualization during electrophysiologic diagnostic or therapeutic procedures. The invention is particularly applicable to catheter ablation, e.g., ablation of atrial fibrillation. In embodiments which are useful for catheter ablation, the combined electrophysiology and imaging antenna catheter may further include an ablation tip, and such embodiment may be used as an intracardiac device to both deliver energy to selected areas of tissue and visualize the resulting ablation lesions, thereby greatly simplifying production of continuous linear lesions. The invention further includes embodiments useful for guiding electrophysiologic diagnostic and therapeutic procedures other than ablation. Imaging of ablation lesions may be further enhanced by use of MR contrast agents. The antenna utilized in the combined electrophysiology and imaging catheter for receiving MR signals is preferably of the coaxial or “loopless” type. High-resolution images from the antenna may be combined with low-resolution images from surface coils of the MR scanner to produce a composite image. The invention further provides a system for eliminating the pickup of RF energy in which intracardiac wires are detuned by filtering so that they become very inefficient antennas. An RF filtering system is provided for suppressing the MR imaging signal while not attenuating the RF ablative current. Steering means may be provided for steering the invasive catheter under MR guidance. Other ablative methods can be used such as laser, ultrasound, and low temperatures.

A magnetic resonance (MR) imaging apparatus and technique exploits spatial information inherent in a surface coil array to increase MR image acquisition speed, resolution and / or field of view. Magnetic resonance response signals are acquired simultaneously in the component coils of the array and, using an autocalibration procedure, are formed into two or more signals to fill a corresponding number of lines in the signal measurement data matrix. In a Fourier embodiment, lines of the k-space matrix required for image production are formed using a set of separate, preferably linear combinations of the component coil signals to substitute for spatial modulations normally produced by phase encoding gradients. One or a few additional gradients are applied to acquire autocalibration (ACS) signals extending elsewhere in the data space, and the measured signals are fitted to the ACS signals to develop weights or coefficients for filling additional lines of the matrix from each measurement set. The ACS lines may be taken offset from or in a different orientation than the measured signals, for example, between or across the measured lines. Furthermore, they may be acquired at different positions in k-space, may be performed at times before, during or after the principal imaging sequence, and may be selectively acquired to optimized the fitting for a particular tissue region or feature size. The in vivo fitting procedure is readily automated or implemented in hardware, and produces an enhancement of image speed and / or quality even in highly heterogeneous tissue. A dedicated coil assembly automatically performs the calibration procedure and applies it to measured lines to produce multiple correctly spaced output signals. One application of the internal calibration technique to a subencoding imaging process applies the ACS in the central region of a sparse set of measured signals to quickly form a full FOV low resolution image. The full FOV image is then used to determine coil sensitivity related information and dealias folded images produced from the sparse set.

A time varying current sensor is constructed using surface coils uniformly spaced around a central cavity adapted to receive the conductor through which the current to be measured flows. Accurate and uniform coil geometry is achieved using printed circuit board technology, thereby eliminating the high cost of precision toroidal coil winding. An optional hinge in the housing can allow the sensor to be easily installed on existing conductors without the need to disconnect and reconnect.

An RF coil assembly for use in a multiple receive-channel MRI system is provided. The RF coil assembly is configured as a multi-turn-element RF coil assembly to operate as a surface-coil array in cooperation with the MRI system which is configured to operate in a multiple-channel receive mode.

A method of inducing spin excitation by employing RF transmission fields of time-varying spatial characteristics in order to better control the overall distribution of spin excitation. The MRI transmit inductor system generates an RF transmission of particular spatial characteristics, followed by one or more additional RF transmissions with different spatial characteristics, where the additional RF transmissions alter the spin excitation produced by the first RF transmission. The spin excitation can be provided by a sequence of two or more discrete RF transmissions with different spatial characteristics, by a single RF transmission that has continuously varying spatial characteristics, by using successive RF transmissions of the primary and higher order modes of a volume coil, and / or by an RF transmission from a volume or surface coil followed by a second RF transmission from one or more local surface coils.

A magnetic resonance imaging apparatus acquires magnetic resonance signals by the PI method using an RF coil unit having basic coils serving as surface coils which are arrayed with at least two coils along a static magnetic field direction (z direction) and at least two coils along each of two orthogonal x, y directions. The coils are divided into an upper unit and a lower unit. The upper unit and lower unit are fixed by a band or the like to allow them to be mounted on an object to be examined. The signals detected by the respective surface coils are sent to a data processing system through independent receiver units and formed into a magnetic resonance image.

An RF coil assembly for use in a multiple receive-channel MRI system is provided. The RF coil assembly is configured as a multi-turn-element RF coil assembly 200 to operate as a surface-coil array in cooperation with the MRI system 100 which is configured to operate in a multiple-channel receive mode.

A surface coil array comprises a surface coil support and an arrangement of non-overlapping magnetically decoupled surface coils mounted on the support. The surface coils encompass a volume into which a target to be imaged is placed. Magnetic decoupling circuits act between adjacent surface coils. Impedance matching circuitry couples the surface coils to conventional transmit and receive components.

A restraining apparatus and method for limiting motion on the macro and micro scale during MRI and CT scans, by providing a custom fit, while also improving patient comfort. The restraining apparatus includes a disposable component, including castable and expandable sleeves used to fix the patient into a coil. The castable sleeve encircles the limb of a patient, and is filled with a quickly casting material. The cast material is patient compatible and preferably designed to augment imaging. The resulting cast is MRI compatible, safe and rapid setting, which will decrease the time to set up a patient for scanning, thereby further improving MRI productivity. The expandable sleeve encircles the castable sleeve and is inflatable such that the expandable sleeve conforms to the inner dimensions of a particular MRI coil, CT scanner, or other imaging device. Alternatively, the apparatus includes a castable sleeve for casting around a flex / wrap or surface coil. The surface coil is first cast around the limb of a patient, then the patient is fixed to the magnet.

A magnetic resonance imaging system to be used over a target area of a subject includes first and second RF coils for receiving an RF signal from the subject. The first RF coil is fixed to a position device and movable over the target area of subject. The second RF coil is larger than the first RF coil and has a larger field of view than the first RF coil. The system further includes an image processing device programmed to process RF signals coupled from the first RF coil and the second RF coil to form an MRI image.

A controller includes an operating member operable by user's depression, and a touch detection device constructed to detect a depressing touch on the operating member. The touch detection device includes a movable contact pattern provided on the lower surface of the operating member, and a fixed contact pattern disposed underneath the operating member. One of the fixed and movable contact patterns is a coil-shaped contact pattern while the other of the fixed and movable contact patterns is a uniform surface pattern, at least one of the fixed and movable contact patterns has flexibility, and at least one of the fixed and movable contact patterns has a surface slanted from the center of the coil toward the outer peripheral edge of the coil. The coil-shaped contact pattern comprises first and second contact elements constituting a dual coil pattern.

A magnetic resonance imaging method employs sub-sampled signal acquisition from a number of receiver coils such as surface coils. A full field-of-view magnetic resonance image is reconstructed on the basis of the sensitivity profiles of the receiver coils, for example on the basis of the SENSE technique. The reconstruction is carried out mathematically as an optimization, for example, requiring a minimum noise level in the magnetic resonance image. According to the invention, a priori information is also involved in the reconstruction and the a priori information is taken into account especially as a constraint in optimization.

A switchable birdcage coil functioning as a transmitter coil and a separate RF surface coil functioning as the receiver coil are utilize in NMR and MRI apparatus. To prevent the switchable birdcage coil from absorbing energy by coupling to the receiver coil or by absorbing power from the RF field produced by the precessing nuclear spins, one or more of the reactive elements of the birdcage coil are switched from a normal reactive impedance state to a high impedance state. The high impedance state is formed by switchably combining the reactive element with a complementary reactive element thereby forming parallel resonant high impedance circuit that is tuned to resonate at the NMR frequency.

A magnetic resonance imaging method employs sub-sampled signal acquisition from a number of receiver coils such as surface coils. A full field-of-view magnetic resonance image is reconstructed on the basis of the sensitivity profiles of the receiver coils, for example on the basis of the SENSE technique. The reconstruction is carried out mathematically as an optimization, for example, requiring a minimum noise level in the magnetic resonance image. According to the invention, a priori information is also involved in the reconstruction and the a priori information is taken into account especially as a constraint in said optimization.

The invention relates to a filling reclamation method for reclaiming coal mining subsidence lands by Yellow River sediment and belongs to the technical field of mine environment protection. The filling reclamation method includes: confirming trends and sizes of Yellow River sediment filling strips according to the sizes and the shapes of a subsided basin to be filled; draining accumulated water in the subsidence land via existing drainage ditches around the subsidence land, and building a field path and drainage ditches along the vertical filling trend in the central area of the subsidence land; confirming the soil stripping depth of every strip according to the sediment depth, the available soil depth and reclamation elevation of every strip to be filled, stripping surface soil from subsoil in a strip-separated and layered stripping manner, and piling the surface soil and the subsoil on two sides of every strip; filling along a direction from two ends of the strips perpendicular to the central drainage ditches to the drainage ditches, covering the strips by the subsoil and the surface coil sequentially in a reasonable thickness after drainage consolidation of the filled sediment, and finally leveling the land to form a reconstructed soil profile. The filling reclamation method provides technical supports for filling reclamation of the coal mining subsidence lands by the Yellow River sediment.

According to the invention, a magnetic field gradiometer detector for detecting a material of interest positioned in a detecting region outside the detector includes a transmitter for generating an output signal at a selected frequency, a receiver for detecting the signal, a probe, and a switch coupling the receiver and transmitter with the probe that alternately connects and disconnects the receiver and transmitter to the probe, switching between transmitting and receiving. The probe includes tuning elements and a gradiometer coil array. The gradiometer coil array includes a first surface coil and a second surface coil wound in an opposite sense, the probe having a first side and an opposite second side, with the first and second surface coils configured asymmetrically such that the probe projects a magnetic field in the outside detecting region adjacent to the first side while being self-shielded on the second side. Accordingly, the material of interest is detected with increased sensitivity and accuracy in the detecting region with the detector shielded from outside RF sources.

Embodiments of the subject invention can utilize a single coil structure for dual-mode operation. In a specific embodiment, a single coil structure can be used as a volume coil in the transmitting phase and as a phase array in the receiving phase. In an embodiment, a transmit coil array in accordance with the subject invention can be utilized for one or more of the following: 1) parallel RF excitation on an MRI scanner equipped with a multiple-channel transmitter; 2) serial RF excitation with the use of a switch system with a single channel transmitter; and 3) generation of a homogeneous B1 field for regular MRI with the use of a power splitter on a standard scanner. In a specific embodiment, the use of a concentric double loop coil with different tunings of inner and outer loops can be implemented. In an embodiment, the coil elements can be decoupled using the CRC mode of a concentric double loop coil. In an embodiment, a surface coil transmit array can provide better compatibility with a receive array. In a specific embodiment, an over-coupled technique can be used to improve the phase control of the transmitting pulse.

A magnetic resonance surface coil unit has at least one magnetic resonance coil surrounded by a closed housing wherein the housing has at least one recessed grip, and the recessed grip is formed by an oblong access opening to the cavity arranged inside of the housing. The cavity extends behind the access opening to one side in the direction of a shorter dimension of the access opening, such that a region of the housing bordering the access opening forms a grip part of the recessed grip. The recessed grip can be arranged in a region surrounded by a magnetic resonance coil.

A multi-layer coil is wound around a bobbin having a center pillar and a small and a large flanges connected to longitudinal ends of the center pillar. A winding space having a trapezoidal cross-section in a plane cut through the center axis of the bobbin is formed outside the center pillar between both flanges. To wind the multi-layer coil in this winding space, a turning position where a layer of the coil moves up to a higher layer is set by a position setter, and the turning position is automatically shifted layer by layer to form a sloped outer surface of the coil. The coil is wound in a shape fitting the trapezoidal winding space without reducing the winding speed. The space factor of the coil in the winding space is improved, making the coil compact in size.

To provide a diagnostic apparatus utilizing nuclear magnetic resonance suitable for interventional MRI which is not limited as to selection of an imaging section and an phase-encoding axis, the reception coil thereof includes three loop coils arranged so as to surround an object to be examined and to be within a plane including a line segment parallel to a static magnetic field direction, and two surface coils arranged in the vicinity of the surface of the object within a plane including a line segment perpendicular to the static magnetic field direction. In the reception coil, two or more sub-coils have nonuniform sensitivity profiles along an arbitrary axis. Therefore, the reception coil configured to have sensitivity throughout the imaging areas can be realized.

A system and method for decoupling coils in a medical imaging system are provided. The coil system includes a first coil of a medical imaging system, a second coil of the medical imaging system, and a balun device connected to the first and second coils. The balun device is configured to decouple the first and second coils of the medical imaging system.

A magnetic resonance imaging method is proposed wherein a magnetic resonance image is reconstructed from magnetic resonance signals from respective signal channels. More specifically, individual signal channels relate to respective surface coils which are employed as receiver antennas for the magnetic resonance signals. The magnetic resonance signals are acquired with sub-sampling of the k-space. Resampling on a regular square grid is performed, thus enabling fast Fourier transformation in the reconstruction of the magnetic resonance image. Furthermore, the reconstruction is carried out on the basis of the spatial sensitivity profile of the receiver antennas, i.e. of the surface coils, so as to separate contributions from different spatial positions in the sub-sampled magnetic resonance signals. Preferably, a spiral-shaped acquisition trajectory is followed in the k-space.

For in vivo magnetic resonance imaging at high field (≧3 T) it is essential to consider the homogeneity of the active B1 field (B1+), particularly if surface coils are used for RF transmission. A new method is presented for highly rapid B1+ magnitude mapping. It combines the double angle method with a B1-insensitive magnetization-reset sequence such that the choice of repetition time (TR) is independent of T1 and with a multi-slice segmented (spiral) acquisition to achieve volumetric coverage with adequate spatial resolution in a few seconds.

A radio-frequency (RF) coil system that simplifies multi-nuclear magnetic resonance (MR) imaging is disclosed herein. The RF coil system comprises a transmitter coil (102) for transmitting an RF signal to excite a target region of a subject. The RF coil system also comprises an independent planar receiver coil assembly (110) for receiving an MR signal from at least a portion of the target region, the planar receiver coil assembly (110) being configured to include an on-board digital receiver circuit (112) for processing the received MR signal.

A method, system and apparatus provides a magnetic resonance (MR) responsive field of view within a volume of a patient. At least two radiofrequency (RF) surface coils are provided that at least in part MR responsively cover the volume, at least one MR responsive microcoil is provided within the volume, and MR responsive fields are simultaneously generated from the at least two RF surface coils and the at least one microcoil. The data of the RF responsive fields are then integrated with parallel imaging methods.

An RF coil having at least three different resonance frequencies, wherein one of the resonance frequencies is adjusted to be a frequency fA of a magnetic resonance signal generated by a test subject, and the coil is adjusted so that ratio of difference between the frequency fA and a first frequency fB lower than fA and nearest to fA among the resonance frequencies (fA−fB), and difference between the frequency fA and a second resonance frequency fC higher than fA and nearest to the frequency fA among the resonance frequencies (fC−fA), should be from 0.5 to 2.0. There is provided a technique for receiving magnetic resonance signals always with high detection efficiency by an RF coil of an MRI apparatus even if significant loss is caused in the RF coil, or test subject is changed.

In order to reduce the cost for isolation between a surface coil and a body coil installed on a magnet assembly side, an RF shield for a surface coil is disposed between a body coil installed on a magnet assembly side of an MRI apparatus and a surface coil body not installed on the magnet assembly side. The reception by the body coil of RF pulses transmitted from the surface coil body is suppressed by the RF shield for the surface coil. Since an induced voltage in the body coil drops to a great extent, a switch provided on the body coil side no longer requires a component resistant to high voltage and high current. Thus, the apparatus can be simplified and the cost can be reduced. As a result, the reliability of the apparatus is improved.

A method for calculating a sensitivity distribution of a receive coil and taking a tomographic image of a subject, based on magnetic resonance signals received by a surface coil in an imaging sequence with a plurality of different echo times TE1 and TE2 in a reference scan, a plurality of reference images are produced by a first reference image producing section; and based on the plurality of reference images, a T2 relaxation time is calculated by a T2 relaxation time calculating section. Then, based on the calculated T2 relaxation time, a T2-weighted image at the echo time TE2 is calculated by a T2-weighted image calculating section, and thereafter, based on the reference image and T2-weighted image at the echo time TE2, a sensitivity distribution is calculated by a sensitivity distribution calculating section. Based on the sensitivity distribution, a tomographic image by an actual scan is corrected by a correcting section.

For in vivo magnetic resonance imaging at high field (≧3 T) it is essential to consider the homogeneity of the active B1 field (B1+), particularly if surface coils are used for RF transmission. A new method is presented for highly rapid B1+ magnitude mapping. It combines the double angle method with a B1-insensitive magnetization-reset sequence such that the choice of repetition time (TR) is independent of T1 and with a multi-slice segmented (spiral) acquisition to achieve volumetric coverage with adequate spatial resolution in a few seconds.

A Radio Frequency (RF) coil apparatus for generating a Magnetic Resonance (MR) image includes a body adapted to be worn by a subject being scanned, the body comprising an anterior portion, a posterior portion, and a transition portion coupled between the anterior and posterior portions, a first RF receive-only saddle coil including a first coil positioned in the anterior portion and a second coil positioned in the anterior portion, the first RF saddle coil configured to be positioned on the anterior and posterior sides of the subject. An MRI imaging system and method are also described herein.