31 results about "Field homogeneity" patented technology

Multiple methods of performing whole body scans using a cost-effective small magnetic resonance imaging (MRI) system are disclosed. High magnetic field homogeneity of an open, small MRI is obtained by a combination of passive shimming and high order active shimming. A dynamic shimming while imaging (DSWI) method is provided to dynamically optimize field homogeneity for each scanned slab (slice) during imaging. Also provided is a method that scan a large subject volume only using a limited optimal imaging region of a magnet by continuously adjusting patient position and orientations with a 6 degrees of freedom patient table.

A method of making an organic light emitting device (OLED) is disclosed wherein an inert insulating conformal smoothing layer is deposited over a protruding structure. The smoothing layer is patterned to expose portions of the structure underlying the smoothing layer and defining active regions of the device. The inert smoothing layer is treated, preferably by heat reflow, to taper the layer over the stepped edges of the structure on the exposed portions. Additional layers are then deposited over the smoothing layer and the exposed portions of the structure. The smoothing layer blunts all underlying layer edges and provides sloped edges wherever a step occurs from one layer to another. This effect results in a homogeneous field across the pixel and the continuity in the layers deposited after the photoresist layer.

The invention relates to a method of CEST or APT MR imaging of at least a portion of a body (10) placed in a main magnetic field B₀ within the examination volume of a MR device. The method of the invention comprises the following steps: •a) subjecting the portion of the body (10) to a saturation RF pulse at a saturation frequency offset; •b) subjecting the portion of the body (10) to an imaging sequence comprising at least one excitation/refocusing RF pulse and switched magnetic field gradients, whereby MR signals are acquired from the portion of the body (10) as spin echo signals; •c) repeating steps a) and b) two or more times, wherein the saturation frequency offset and/or a echo time shift in the imaging sequence are varied, such that a different combination of saturation frequency offset and echo time shift is applied in two or more of the repetitions; •d) reconstructing a MR image and/or B₀ field homogeneity corrected APT/CEST images from the acquired MR signals. Moreover, the invention relates to a MR device (1) for carrying out the method of the invention and to a computer program to be run on a MR device.

In a method for determination and evaluation of a shim parameter set for controlling a shim device in a magnetic resonance (MR) apparatus, the shim device is set using a first shim parameter set, a first field distribution is measured in a body region encompassing a target volume from which MR data are to be acquired, a second shim parameter set is determined using an algorithm for optimization of the field homogeneity in the target volume on the basis of the first shim parameter set and dependent on the first field distribution, a second field distribution is determined on the basis of the second shim parameter set, and the shim parameter sets are evaluated by indirect or direct comparison of the first field distribution and the second field distribution, in particular in the target volume.

In a coil arrangement for nuclear magnetic resonance comprising a main coil (13), a shielding coil (14), and at least one correction coil (41), the function of which consists in forming a magnetic field gradient with eddy current properties which are as good as possible, the main coil (13) and the shielding coil (14) are electrically connected in series with the correction coil (41). The deviations of the residual field from the desired design generated by production tolerances are thereby modified by the correction coil in such a fashion that the long-lasting eddy currents are suppressed. This either reduces the waiting time that must lapse after a gradient pulse before a predetermined field homogeneity is achieved or e.g. the deviations from the desired field are minimized in imaging applications.

The present invention is directed to a method of shimming a magnet assembly of an MR imaging system such that a desired B0 field strength may be created with minimal inhomogeneities therethrough. With this method, sufficient shimming of the magnet assembly may be achieved without requiring mechanical variations to the magnet assembly after the magnet assembly has been assembled. The invention analyzes variations from the desired B0 field and inhomogeneities at a number of target points along the magnet assembly or B0 field. A comparison is then made at each point to determine a shimming or weighting factor such that the desired overall B0 field strength and targeted field homogeneity is achieved. Active and/or passive shim elements may then be incorporated into the magnet assembly at each target point to achieve the desired overall field strength and minimum overall field homogeneity.

The invention discloses a homogeneity test method for homogeneity of color display, which comprises: collecting image with image collector, filtering with mean value average filter device, partitioning image with image partition device, calculating lightness and colority and homogeneity of white field by opposite device. This invention decides the homogeneity of white field for whole screen with uniform standard instead of manual decision to avoid test error and ensure consistency.

A shim coil design technique determines a position and a geometry of a room temperature (RT) shim coil to provide both a desired field homogeneity and a desired B₀ field setting time. The simultaneous satisfaction of both field homogeneity and field settling time is achieved without a reduction of flux leakage from the shim coil, modification of main magnet protection circuitry, and without necessarily decoupling of the shim coil from the overall main magnet.

An electronic transmission range selection (ETRS) system for a motor vehicle transmission includes an ETRS housing disposed on the transmission, the ETRS housing having a magnetic field sensor in communication with a transmission controller; and a magnetic field source including a magnet component and a high magnetic permeability component. The magnetic field source disposed on a transmission selector shaft, the magnetic field source detectable by the magnetic field sensor at a plurality of predetermined positions along a movement path of the transmission selector shaft; and the magnetic field sensor detecting magnetic flux generated by the magnetic field source, and communicating magnetic field source position information to the controller. The high magnetic permeability component homogenizes the magnetic flux generated by the magnet component and the controller generates an electronic transmission mode signal based on the magnetic field source position information.

The invention relates to the technical field of experimental fluid mechanics and aerodynamics and discloses an active rotation type airflow field test system. The system comprises a flow equalizing acceleration duct and a rotation mechanism, in the flow equalizing acceleration duct, the cross section area of a contraction section is gradually reduced along the air inlet direction; the test section is of a cylindrical ventilation structure and is used for placing a test object; the sectional area of the diffusion section is gradually increased in the air inlet direction; the contraction section, the test section and the diffusion section are symmetrical structures taking the first reference surface as a symmetrical central surface; in the contraction section, a distance from the midpoint of the air inlet inner side edge to the second reference surface is the maximum value a of the distance from any point in the air inlet inner side edge to the second reference surface, a distance from the midpoint of the air inlet outer side edge to the second reference surface is the maximum value b of the distance from any point in the air inlet outer side edge to the second reference surface, and b is smaller than a. In the active rotary airflow field test system, the flow field homogeneity in the test section is ensured through the flow-equalizing acceleration duct (and the asymmetric honeycomb device) with a specific structure.

An apparatus and method for dynamically stabilizing the fields in a permanent magnet assembly, including a nuclear magnetic resonance machine. One or more magnetically active elements affect the fields of the magnet assembly. A mechanism controls and changes the position(s) of the magnetically active element(s) to affect and adjust the magnetic field strength in the working volume of the assembly. A sensor provides a control signal indicating the status of the magnetic field strength, and an algorithm is executed for determining, based on the signal, the manner in which the adjustment should be made. The adjustment may be continuous and dynamic, and stabilization of the field may occur during operation of the permanent magnet assembly. The adjustments of the position of the magnetically active element stabilize the field without unduly degrading the field homogeneity, even for high homogeneity magnets.