Abstract: In a method for diffusion-weighted MR-imaging of an object, which undergoes a cyclic motion, a first sub-period type of the cyclic motion is predicted for a first acquisition timeframe, where the first sub-period type corresponds to one of two or more predefined characteristic types of sub-periods of the cyclic motion. A first amount of diffusion-weighting may be selected based on the first sub-period type. A first MR-acquisition may be carried out during the first acquisition timeframe, where a diffusion-weighting according to the first amount of diffusion-weighting is applied. An MR-image of the object is generated based on MR-data including a first MR-dataset obtained as a result of the first MR-acquisition.

Abstract: In a method for determining at least one test position for a test measurement to be recorded by means of a magnetic resonance system, a test image is recorded, and at least one test position is selected based on the test image. With methods for the compensation of effects of deviations of gradients actually generated during a readout duration from gradients planned for this readout time duration, the selection of test positions according to the disclosure based on a test image advantageously ensures that the test positions lie in a recording region favorable for the test measurement, e.g. also within an examination object to be examined in the test image. A higher image quality in MR images, which were generated using test measurements carried out at test positions positioned according to the disclosure, can therefore be achieved.

Abstract: Techniques are described for complex preprocessing steps to ensure consistency of sorted sets of reference measurement data, which have conventionally been required when sorting reference measurement data sets for DPG algorithms captured using an EPI technique, to be omitted because items of reference measurement data captured via the described techniques are already consistent in themselves. Therefore, for each polarity of the read-out gradients, a set of fully sampled reference measurement data is available, which is already suitable for carrying out a dual-polarity (DP) algorithm without any further measures.

Abstract: Method for separating measurement data of an examination object, which data was acquired in collapsed form simultaneously for slices using an EPI SMS technique, into measurement data of individual slices, first and second sets of reference measurement data for separating the measurement data are acquired for each of the slices using a GRE acquisition technique, wherein the reference measurement data in the first set is acquired during switching of readout gradients of a first polarity, and the reference measurement data in the second set is acquired during switching of readout gradients of a second polarity. Based on the two sets of reference measurement data, corresponding separate first calibration data is determined from the reference measurement data acquired using a GRE acquisition technique while switching readout gradients of a first polarity, and second calibration data is determined from the reference measurement data acquired while switching readout gradients of a second polarity.

Abstract: A method for preparing magnetic resonance imaging of an object under examination is described. A plurality of representative pulse sequence segments are generated, each of which is associated with a reference gradient amplitude of the gradient pulse having the highest stimulation potential of the representative pulse sequence segment, and the stimulation potential of which is representative of a group of partially different pulse sequences. For each of the representative pulse sequence segments, a maximum gradient slew rate is determined for which a permitted maximum value of the stimulation potential is not exceeded. One of the representative pulse sequence segments is determined and selected, for a measurement protocol to be planned for a magnetic resonance imaging to be performed, according to the gradient amplitude of the gradient pulse having the highest stimulation potential of a pulse sequence segment of the pulse sequence on which the measurement protocol is based.

Abstract: Techniques are provided for performing echo planar imaging (EPI) data correction. This includes obtaining positive and negative readout gradient calibration data of an imaging target through non-accelerated EPI acquisitions; respectively adopting first and second DPG kernels to be fitted and respectively used to eliminate phase errors of positive and negative readout gradients to fit the positive and negative readout gradient calibration data of the imaging target, with the fitting targets being positive and negative readout gradient data, respectively, in ghost-free target ACS data, and obtaining, after the fitting, a first and a second DPG kernel for final use; obtaining imaging data of the imaging target through an EPI acquisition; adopting the first and second DPG kernels to correct the phase errors of the imaging data to obtain phase-error-free imaging data.

Abstract: A technique for slice-specific correction of scan data recorded for at least two slices simultaneously of an examination object via an EPI-SMS is provided. The technique comprises recording slice separation reference scan data, generating scan data that is to be corrected, and recording phase-encoded navigator signals simultaneously for the at least two slices after an RF excitation pulse radiated into the examination object and before the recording of scan data to be corrected. The at least one navigator signal is recorded for each possible polarity and different phase-encoding of the navigator signals that is used. The technique further comprises separating the navigator signals simultaneously recorded for the at least two slices into single-slice navigator signals using the slice separation reference scan data, determining slice-specific correction data from the single-slice navigator signals, and correcting scan data that is to be corrected by means of the slice-specific correction data.

Abstract: A method for determining a parameter setting for a gradient power of a magnetic resonance system by an electronic computing device. The method includes specifying a limit value for a nerve stimulation in the case of a person positioned in the magnetic resonance system, entering at least one gradient parameter for a pulse of the gradient power as the parameter setting by an input device of the electronic computing device, approximating a potential nerve stimulation as a function of the at least one gradient parameter by a predefined mathematical model of the electronic computing device, comparing the approximated potential nerve stimulation with the predefined limit value by the electronic computing device, and determining the parameter setting as a function of the comparison.

Abstract: In a method for slice-specific correction of scan data recorded for at least two slices simultaneously of an examination object using an EPI-SMS technique, navigator signals encoded in a slice selection direction using a bipolar readout gradient for the at least two slices temporally after a RF excitation pulse radiated into the examination object and temporally before the recording of scan data to be corrected may be simultaneously recorded. Mean navigator signal(s) from at least two of the recorded navigator signals of a same polarity may be determined. Single-slice navigator signals may be determined based on the mean navigator signal and a navigator signal having been recorded with the same polarity as the mean navigator signal(s), but with a different slice selection encoding. Slice-specific correction data from the single-slice navigator signals may be determined, and scan data may be corrected based on the slice-specific correction data.

Abstract: A technique for slice-specific correction of scan data recorded for at least two slices simultaneously of an examination object via an EPI-SMS is provided. The technique comprises recording slice separation reference scan data, generating scan data that is to be corrected, and recording phase-encoded navigator signals simultaneously for the at least two slices after an RF excitation pulse radiated into the examination object and before the recording of scan data to be corrected. The at least one navigator signal is recorded for each possible polarity and different phase-encoding of the navigator signals that is used. The technique further comprises separating the navigator signals simultaneously recorded for the at least two slices into single-slice navigator signals using the slice separation reference scan data, determining slice-specific correction data from the single-slice navigator signals, and correcting scan data that is to be corrected by means of the slice-specific correction data.

Abstract: To acquire measurement data of an object, a first subsampled set of diffusion-weighted measurement data with switching of diffusion gradients for diffusion encoding of the measurement data, using a first echo spacing, and a second subsampled set of non-diffusion-weighted measurement data, using the first echo spacing, are acquired. The first and second subsampled sets of measurement data are supplemented using calibration data to produce first and second complete sets of measurement data. At least the first calibration data, acquired using the first echo spacing, may be used for supplementing the second subsampled set of measurement data to produce a second complete set of measurement data. By supplementing subsampled sets of measurement data with calibration data acquired according to the same echo spacing as the subsampled measurement data, noise signals in the supplemented measurement data are advantageously eliminated.

Abstract: In a method and system for acquiring measurement data reference data for a phase correction of the measurement data, a RF excitation pulse is provided to excite spins in the object under examination, one or more RF refocusing pulses are provided to refocus the spins excited by the RF excitation pulse, measurement data is acquired by recording echo signals of refocused spins excited by the RF excitation pulse by switching readout gradients that alternate in their polarity, at least two echo signals are recorded while switching readout gradients with different polarity acquire reference data, chronologically between the providing of the RF excitation pulse and the acquisition of the measurement data, and correction data is determined for phase correction of phase errors contained in the measurement data based on the acquired reference data.

Abstract: A method for avoiding artifacts in measurement data captured using a magnetic resonance system which has a gradient unit.

Abstract: The invention relates to a method for acquiring a magnetic resonance image dataset of a subject, a magnetic resonance imaging system and a non-transitory computer-readable medium. The method comprises the steps: (a) determining scan conditions relating to an imaging protocol which is to be carried out on the subject; (b) based on the scan conditions and/or on predetermined reference parameters, determining whether at least one imaging preparation procedure may be omitted or accelerated to have a shortened duration; (c) depending on the determination of step (b), omitting or carrying out the least one imaging preparation procedure at the standard or at the shortened duration; (d) carrying out the imaging protocol in order to acquire the magnetic resonance image dataset.

Abstract: In a method for recording diffusion-weighted measurement data, using a MR system with diffusion weightings with two+ different b-values, diffusion directions and diffusion weightings with the associated b-values to be used for the desired recordings are loaded, a sequence of recordings of measurement data to be recorded consecutively are determined by sorting the diffusion directions and diffusion weightings to be recorded based on their associated b-value, such that the b-value of a recording of measurement data is less than the b-value of the immediately preceding recording of measurement data by no more than a predetermined threshold value, and the recordings are recorded based on the determined sequence. By arranging diffusion encodings for the desired recordings to be used consecutively, abrupt discontinuities in the b-values used chronologically are prevented, thereby eddy current effects from preceding recordings have time to abate in the case of recordings with small b-values.

Abstract: Techniques are disclosed for capturing scan data of an examination object via a magnetic resonance system. The techniques include capturing a first set of a diffusion-weighted scan data by excitation and, in an acquisition phase, acquiring a first echo signal, wherein before the acquisition phase in a diffusion preparation phase, diffusion gradients are switched for diffusion encoding of the scan data, The techniques additionally include capturing a second set of non-diffusion-weighted scan data by excitation and, in an acquisition phase, acquiring a second echo signal, wherein before the acquisition phase, in a diffusion preparation phase, the same diffusion gradients are switched as are switched for diffusion encoding of the scan data of the first set of diffusion-weighted scan data, although they have no influence on the second echo signal. Diffusion-weighted and non-diffusion-weighted scan data is thereby captured, having identical disturbances caused by eddy currents induced by switched gradients.

Abstract: In a method for correcting influences on magnetic resonance imaging of an examination object caused by fluctuations in a basic magnetic field, an MR data set is generated for two or more measurement periods, and a regression analysis is performed. Each of the MR data sets may contain at least one two-dimensional individual data set. The regression analysis may determine at least one phase correction value for a measurement period to be corrected. Two or more different individual data sets may be taken into account in the analysis. An MR image may generated based on the MR data sets and the at least one phase correction value.

Abstract: In a method for acquiring measurement data using a magnetic resonance (MR) system having a gradient unit, frequency-dependent parameters characterizing the gradient unit of the MR system are accessed (e.g. loaded from a memory), a k-space trajectory of a RESOLVE (Readout Segmentation Of Long Variable Echo trains) sequence planned for a MR measurement is accessed, MR measurement data is acquired based on the planned k-space trajectory and reconstructing image data from the MR measurement data, and an electronic signal is provided that represents the reconstructed image data as an output of the MR system. The k-space trajectory may have a frequency component in at least one direction. The planned k-space trajectory may be corrected based on at least one frequency component of the planned k-space trajectory and the frequency-dependent parameters.

Abstract: Calibration data is generated for completing undersampled measurement data acquired via a magnetic resonance system. This includes recording N measurement data sets using an acquisition scheme, and undersampling the k-space with an acceleration factor R, with N being greater than or equal to R, and the N measurement data sets together scanning the k-space completely. Phase images are generated from the N recorded measurement data sets, at least one homogeneity value of the created phase images is determined, and a complete calibration data set is generated based upon the recorded measurement data sets, taking into account the at least one homogeneity value. Thus, it is possible to determine which measurement data sets are subject to undesired phase errors, the measurement data sets used for the creation of the calibration data sets can be selected optimally, and input of the detected phase errors into the calibration data sets can be avoided.

Abstract: In a method for determining at least one test position for a test measurement to be recorded by means of a magnetic resonance system, a test image is recorded, and at least one test position is selected based on the test image. With methods for the compensation of effects of deviations of gradients actually generated during a readout duration from gradients planned for this readout time duration, the selection of test positions according to the disclosure based on a test image advantageously ensures that the test positions lie in a recording region favorable for the test measurement, e.g. also within an examination object to be examined in the test image. A higher image quality in MR images, which were generated using test measurements carried out at test positions positioned according to the disclosure, can therefore be achieved.