摘要:
In a method for magnetic resonance imaging, whereby magnetic resonance signals in a region of interest of an examination subject are generated in an examination by applying radio-frequency pulses of a first transmission field strength and the magnetic resonance signals are acquired in a spatially coded manner and allocated to volume elements of the region of interest in order to obtain one or more magnetic resonance images of the region of interest, the sensitivity of each volume element of the region of interest with respect to a modification of the first transmission field strength is determined, deviations of the first transmission field strength from a reference field strength are measured during the examination, and the magnetic resonance signals acquired in the examination are corrected on the basis of the sensitivity determined for each volume element and on the basis of the measured deviations of the first transmission field strength from the reference field strength. The method enables the implementation of fMRI measurements with high precision given fluctuating transmission field strength.
摘要:
In an active electrical device with an electrical line for operation in the examination volume of a nuclear spin tomography device, a sheath wave trap tuned to the operating frequency of the nuclear spin tomography device is installed in the line.
摘要:
In MR imaging of a predetermined volume segment of a living examination subject, the examination subject is stimulated with a defined stimulation pattern, MR data of the predetermined volume segment, are acquired, and MR images based on the MR data are generated that depend on the stimulation pattern. The predetermined volume segment is an internal organ or muscle tissue of the examination subject.
摘要:
Paired optically variable security element which includes first and second optically variable thin-film multilayer interference devices in the form of optically variable foils or of printings made with inks having optically variable interference pigments. The first and second interference devices exhibit spectral matching at a determined angle of incidence. Sets of optically variable devices and of coating compositions include optically variable pigments for the production of the paired optically variable security element. Moreover, the security element can be used for the protection of documents and goods, and security documents and goods.
摘要:
In a method and a device for phase-sensitive flow measurement of a volume segment of an examination subject in a measurement system, the volume segment is divided into multiple partial volume segments and the following steps are executed repeatedly until the volume segment has been completely measured: movement of a table such that a center of one of the partial volume segments to be measured essentially corresponds to the isocenter of the magnetic resonance system, and implementation of the phase-sensitive flow measurement for the partial volume segment to be measured while the center of the partial volume segment essentially corresponds to the isocenter.
摘要:
A computer-implemented method for learning a tight frame includes acquiring undersampled k-space data over a time period using an interleaved process. An average of the undersampled k-space data is determined and a reference image is generated based on the average of the undersampled k-space data. Next, a tight frame operator is determined based on the reference image. Then, a reconstructed image data is generated from the undersampled k-space data via a sparse reconstruction which utilizes the tight frame operator.
摘要:
A method for estimating a coil sensitivity map for a magnetic resonance (MR) image includes providing a matrix A of sliding blocks of a 3D image of coil calibration data, calculating a left singular matrix V∥ from a singular value decomposition of A corresponding to τ leading singular values, calculating P=V∥V∥H, calculating a matrix S that is an inverse Fourier transform of a zero-padded matrix P, and solving MHcr=(Sr)Hcr for cr, where cr is a vector of coil sensitivity maps for all coils at spatial location r, and M = ( ( 1 1 … 1 0 0 … 0 … … … 0 0 … 0 ) ( 0 0 … 0 1 1 … 1 … … … 0 0 … 0 ) … ( 0 0 … 0 0 0 … 0 … … … 1 1 … 1 ) ) .
摘要:
The invention discloses a security element having a coating layer which appears transparent at certain angles of view, giving visual access to underlying information, whilst staying opaque at other angles of view. Documents of value, right, identity, security labels or branded goods comprising said security element, as well as a method for producing said security element, are also disclosed. Using appropriate substrate surfaces, optically variable and otherwise angle-dependent visual effects can be realized.
摘要:
A method and system for automated view planning for cardiac magnetic resonance imaging (MRI) acquisition is disclosed. The method and system automatically generate a full scan prescription using a single 3D MRI volume. The left ventricle (LV) is segmented in the 3D MRI volume. Cardiac landmarks are detected in the automatically prescribed slices. A full scan prescription, including a short axis stack and 2-chamber, 3-chamber, and 4-chamber views, is automatically generated based on cardiac anchors provided by the segmented left ventricle and the detected cardiac landmarks in the 3D MRI volume.
摘要:
The invention discloses a device and a process for producing indicia comprising magnetically oriented magnetic or magnetizable particles in an ink or coating composition on a sheet of substrate material. The device comprises a flat-bed screen-printing unit having a flat printing screen and a printing platen for receiving said sheet, the printing platen having an upper surface facing the printing screen and a first direction along its upper surface along which said sheet is unloadable, and a magnetic orienting unit comprising multiple magnet assemblies. The magnetic orienting unit is disposed below the upper surface of the printing platen, said multiple magnet assemblies are disposed along said first direction, and all of said magnet assemblies are concomitantly movable from a first position away from the upper surface of the printing platen to a second position close to the upper surface of the printing platen.The magnetic orienting unit comprising one or more magnet assemblies can also be used as a stand-alone flat-bed magnetization device, subsequent to the printing process, e.g. as an additional process station following a conventional flat-bed or rotary screen printing unit. Processes of producing printed documents using the disclosed devices are shown as well.