Abstract: A method for generating a magnetic resonance image includes providing MR segment data records, wherein each MR segment data record has N×M frequency voxels in k-space. To reduce the acquisition time during MR segment recordings, the amount of MR data is reduced by incompletely sampling the k-space during a recording. The missing data of the MR segment data records are reconstructed twice: Preliminarily reconstructed MR segment data records are calculated first, with a reconstruction kernel obtained from reference data. Modified reference images containing phase information are obtained by creating phase images from the preliminarily reconstructed MR segment data records and combining these phase images with the absolute value of the reference image generated from the reference data. The second reconstruction kernels are ascertained therefrom in turn. In contrast to the first reconstruction kernel, these contain phase information, such that the missing data can be reconstructed without phase artifacts.

Abstract: Techniques for determining motion states of at least two bodies by an MR-device are provided, wherein the bodies each have a respective target region which is in an anatomic motion comprising a repetitive motion pattern with a motion repetition rate, and in particular, for cardiac and/or respiratory motion. A sequence of individual MR-measurements are performed on the bodies at a MR-repetition rate higher than the motion-repetition rate, wherein nuclear spins of the at least two bodies are excited during the sequence of individual MR-measurements either simultaneously or alternately at navigator times. With the individual MR-measurements, navigator signals are determined, each respective navigator signal indicative of the motion state of at least one of the motion patterns at the navigator time of the navigator signal. These techniques allow simultaneously determining motion states for imaging more than one body with a repetitive motion pattern with reduced preparation time.

Abstract: A hybrid imaging apparatus includes a magnetic resonance imaging (MM) arrangement having an RF resonator structure (1) and a gradient coil system (8) having a longitudinal axis, an emission tomography (ET) arrangement with a detector device having at least one photosensor (3) and one circuit board arrangement with at least one readout circuit board (11) on which an ET electronics is arranged, and an internal shielding device (7) shielding the readout electronics (4) of the ET arrangement and shielding the RF resonator structure of the MRI arrangement. The photosensor is arranged, in relation to the longitudinal axis, radially inside the sensor circuit boards and radially outside the RF resonator structure. The internal shielding device is arranged radially outside the photosensor and/or integrated into the photosensor. This achieves both a compact design and optimized performance of the detection of the MR and ET imaging.

Abstract: A method for establishing and/or reducing artifacts that arise when reconstructing (R) an MPI overall image data record from MPI signal data and an appended system matrix (SMapp(r,f)), wherein the appended system matrix (SMapp(r,f)) includes system matrices of different particle classes (P1, P2). The method includes setting a selection region (cvn(r)) of a reconstructed MPI overall image data record (cn(r)), producing virtual signal data (sn(f)) by inverse transformation of the selection region, reconstructing a virtual overall image data record (c?vn(r)) from the virtual signal data and the appended system matrix, setting an artifact region (cartifact_n(r)) within the reconstructed virtual overall image data record so that the artifact region has only voxels lying outside of the selection region, and assigning the image data present in the artifact region as artifact image data (cartifact_n(r)). This permits ghost artifacts to be corrected.

Abstract: A method for establishing a local concentration distribution of magnetic particles of at least one particle class within an examination volume or a variable derived from this concentration distribution. The method includes providing at least one system matrix, providing MPI signal data of at least one sample including magnetic particles of at least one particle class within a measurement volume, and reconstructing spatially resolved MPI image data from the provided MPI signal data. At least one spatial projection of at least one part of the system matrix is carried out along a projection direction and a projected system matrix is generated thereby. The reconstruction of the MPI image data is implemented with the at least partly projected system matrix, as a result of which MPI image data of a spatial projection of the local concentration distribution of the magnetic particles are produced along the projection direction.

Abstract: A method to generate an attenuation correction map to compensate imaging errors in emission tomography resulting from the presence of hardware parts inside the imaging volume of an emission tomograph. Components of 3-dimensional CAD models of the hardware parts to be compensated are converted into voxels on a predetermined grid and assigned a filling factor per voxel. Image data sets of each component are multiplied with respective attenuation coefficients and thereafter superimposed to form an attenuation correction map. Thereby, in a simple and automatable way a profoundly exact, mostly noise-free and exactly reproducible attenuation correction map for attenuation correction in an emission tomography device may be generated.

Abstract: An MPI-apparatus comprising a magnet system for generating a time-varying and position-dependent magnetic field and a detection system detecting signals from MPI contrast agents exposed to said magnetic field within a detection volume, said signals being suitable for reconstructing an image of the spatial and temporal distribution of said MPI contrast agents, is characterized in that the magnet system comprises an array with a plurality of permanent magnetic elements geometrically arranged in such a way that at least a part of the plurality of permanent magnetic elements are moved with sufficient speed in the vicinity of the detection volume to create the spatial and temporal magnetic field variations for inducing within the contrast agent the MPI signals recorded by the detection system. This avoids the high power requirements of current MPI scanners, while opening the way for higher spatial resolutions and variable scanning frequencies.

Abstract: A device for alternating examination of a measurement object (170) by means of MPI and MRI with two magnetic field-generating elements is presented. The device is characterized by a main magnet coil system with two coaxial partial coil systems (100a1, 100a2; 100b2, 100b1) arranged mirror-symmetrically relative to a central plane running perpendicularly to the z-axis through the first volume under investigation (162). The volumes under investigation are superimposed. A polarity reversal device (190) reverses the polarity of the current through a partial coil system and the main magnet coil system generates a homogeneous magnetic field of at least sixth order in the first volume under investigation when the partial coil systems have identical polarity, and a spatially strongly varying magnetic field profile in the second volume under investigation when the polarities are opposite. Repositioning of the measurement object is thereby simplified or can even be eliminated.

Abstract: A phantom system has a housing (2) with a lower part (3) having an opening in the z-direction and a cover part (4) for closing the opening of the housing (2). A first plate-shaped insert element (10a) has at least one depression (11a) for receiving a liquid substance. The lower part (3) and the cover part (4) delimit a cavity (5) with an insert area (8), which is constituted to receive the first insert element (10a). A first sealing element (14a) seals the first insert element (10a) against the cavity (5) and a fixing facility fixes the first insert element (10a) in the cavity (4) of the housing (2) in an operating state of the MPI phantom. The phantom permits good contrast in MPI, MRI, or ?CT using liquid contrast media.

Abstract: An MPI method determines calibration and measurement volumes, wherein the calibration volume is larger than the measurement volume and the overall measurement volume is arranged within the calibration volume. Calibration signals are detected and a system matrix S is created. An MPI measuring signal u is recorded, a location-dependent magnetic particle concentration c with magnetic particle concentration values ci within the calibration volume is reconstructed and the magnetic particle concentration values ci are associated with voxels in the calibration volume. Magnetic particle concentration values ci which were associated with voxels outside of the measurement volume are discarded and an MPI image is generated which exclusively contains magnetic particle concentration values ci which were associated with the voxels within the measurement volume. MPI image data are thereby generated with little artifacts within a short time even in case of high magnetic particle densities outside of the measurement volume.

Abstract: A calibration method for an MPI (=magnetic particle imaging) apparatus for conducting an MPI experiment, wherein the calibration method comprises m calibration MPI measurements with a calibration test piece and uses these measurements to create an image reconstruction matrix with which the signal contributions of N voxels within an investigation volume of the MPI apparatus are determined, wherein compressed sensing steps are applied in the calibration method with a transformation matrix that sparsifies the image construction matrix, and wherein only a number M<N of calibration MPI measurements for M voxels are carried out, from which the image reconstruction matrix is created and stored. This specifies an efficient method for determination of the system matrix for the MPI imaging method, which does not require much time to determine an MPI system function and nevertheless achieves a high degree of precision.

Abstract: A method for determining the spatial distribution of magnetic resonance signals from at least one of N subvolumes predefines a reception encoding scheme and determines unique spatial encoding for at least one of the subvolumes but not for the entire volume under examination (UV). A transmission encoding scheme is also defined, wherein encoding is effected via the amplitude and/or phase of the transverse magnetization. The temporal amplitude and phase profile of the RF pulses is then calculated and each reception encoding step is carried out I times with variations according to the I transmission encoding steps in the transmission encoding scheme. The method makes it possible to largely restrict the spatially resolving MR signal encoding and image reconstruction to subvolumes of the object under examination without the achievable image quality sensitively depending on imperfections in the MR apparatus.

Abstract: Device for alternating examination of a measurement object (103) by means of MPI and MRI within a magnetic system is characterized in that the magnetic system has a specified magnetic field profile, which is not temporally variable during the alternating examination, and both magnetic field generating elements (101,102; 201,202; 801a,801b,811,812) generate a magnetic field portion, in the first examination region (104) and in the second examination region (105), which is essential for the MRI operation and for the MPI operation, and in that there is a transport apparatus (106) by means of which the measurement object can be moved out of the first examination region and into the second examination region and/or vice versa. The total space requirement for both modalities is thus reduced and the complexity of an integrally designed hybrid system is minimized.

Abstract: A method for generating a desired temporal profile of the magnetization state in an object under examination (O) during an experiment involving magnetic resonance is characterized in that at least one spatially dependent change in the magnetization state inside the object under examination (O) is predefined and spatially selective radio-frequency pulses, which allow a simultaneous and independent change in the magnetization state at locations with different stipulations, are irradiated in order to implement the predefined spatially dependent change in the magnetization state. The method permits establishment of the same desired temporal profile of the magnetization state for different regions of the object under examination despite different given experimental parameters or deliberate generation of different desired profiles of the magnetization state at different locations.

Abstract: A method for determining the position of at least one ferromagnetic particle (30) in a liquid matrix (31) with an MRI system (50). An MRI measurement sequence (MS1, MS2) is applied (20) to a measurement volume (52) in which the particle is situated. The measurement sequence includes a plurality of individual measurements (E1, E2), during each of which there is a spatially encoding gradient switching operation, including an excitation pulse (1) and signal recording (2), via the MRI system. The measurement sequence has a multiplicity of measurement blocks (MB1, MB2), which each include one or more individual measurements and, in a pause of the spatial encoding, an intermediate gradient (ZW) switched by the MRI system. The intermediate gradients are dimensioned such that, averaged over time, the particle is kept substantially in the same position (M1, M2) over each measurement block.

Abstract: A method for magnetic resonance (MR) for imaging an imaging area of an object has a reconstruction image quality which depends on a spatial distribution of background phase. A background phase distribution is initially determined using an optimization algorithm having a reconstruction quality as an optimization criterion, wherein limitation of a spatial variation of a background phase offset distribution is integrated as a boundary condition in the optimization algorithm. At least one spatially selective radio frequency pulse is applied which contributes to generation of an MR signal distribution having a previously determined background phase distribution, wherein the at least one spatially selective radio frequency pulse generates the background phase offset distribution as a part of the background phase distribution. In this fashion, the reconstruction quality is improved in a manner which can be realized using available equipment.

Abstract: A method related to Magnetic Particle Imaging (MPI) includes a signal processing step in which MPI time signals are acquired and successive acquisition cycles are completed within one scanning period. From the scanning period, an image acquisition period is selected for which a composite time signal is generated by concatenating measured values acquired in immediate succession. A corrected time signal is determined from the composite time signal by windowing, performing a Fourier transform, and reducing a number of frequency values by eliminating intermediate frequencies of the Fourier transform of the windowed, composite time signal. In a reconstruction step, a spatial assignment and/or distribution of the magnetic particles is computed, and in an outputting step, the results of the reconstruction and/or one or more parameters derived therefrom are stored and/or displayed.

Abstract: A calibration method for an MPI (=magnetic particle imaging) apparatus for conducting an MPI experiment, wherein the calibration method comprises m calibration MPI measurements with a calibration test piece and uses these measurements to create an image reconstruction matrix with which the signal contributions of N voxels within an investigation volume of the MPI apparatus are determined, wherein compressed sensing steps are applied in the calibration method with a transformation matrix that sparsifies the image construction matrix, and wherein only a number M<N of calibration MPI measurements for M voxels are carried out, from which the image reconstruction matrix is created and stored. This specifies an efficient method for determination of the system matrix for the MPI imaging method, which does not require much time to determine an MPI system function and nevertheless achieves a high degree of precision.

Abstract: A method for determining the spatial distribution of magnetic resonance signals from at least one of N subvolumes predefines a reception encoding scheme and determines unique spatial encoding for at least one of the subvolumes but not for the entire volume under examination (UV). A transmission encoding scheme is also defined, wherein encoding is effected via the amplitude and/or phase of the transverse magnetization. The temporal amplitude and phase profile of the RF pulses is then calculated and each reception encoding step is carried out I times with variations according to the I transmission encoding steps in the transmission encoding scheme. The method makes it possible to largely restrict the spatially resolving MR signal encoding and image reconstruction to subvolumes of the object under examination without the achievable image quality sensitively depending on imperfections in the MR apparatus.

Abstract: A method for generating a desired temporal profile of the magnetization state in an object under examination (O) during an experiment involving magnetic resonance is characterized in that at least one spatially dependent change in the magnetization state inside the object under examination (O) is predefined and spatially selective radio-frequency pulses, which allow a simultaneous and independent change in the magnetization state at locations with different stipulations, are irradiated in order to implement the predefined spatially dependent change in the magnetization state. The method permits establishment of the same desired temporal profile of the magnetization state for different regions of the object under examination despite different given experimental parameters or deliberate generation of different desired profiles of the magnetization state at different locations.