Abstract: In a magnetic resonance fingerprinting method and apparatus for improved determination of local parameter values of an examination object, in which at least two signal comparisons of acquired picture element time series are carried out with comparison signal curves for determination of parameter values. A further (subsequent) signal comparison takes into account results of a preceding signal comparison. This multi-stage determination of parameter values allows an increase of the spatial resolution and the precision with which the parameter values can be determined.

Abstract: The disclosure facilitates determining patient motion during a magnetic resonance protocol and compensating and/or correcting the patient motion. In a method of performing magnetic resonance imaging (MRI), MRI signals are acquired using an MRI protocol, an image domain difference map is determined based on: a subset of the acquired MRI signals and a reference MRI image of the MRI protocol, and a motion of a patient is determined based on the image domain difference map.

Abstract: The disclosure facilitates determining patient motion during a magnetic resonance protocol. According to some examples, the patient motion may be corrected or compensated.

Abstract: In order to execute a low-artifact magnetic resonance fingerprinting (MRF) scan, a preferred order of N k-space trajectories of a sampling pattern is determined in a computer, along which in each case an undersampled scan data set is to be scanned, such that artifacts are avoided in parameter maps created from the scan data sets in an MRF scan. The order in which the N k-space trajectories are to be sampled one after the other is varied, so at least two different orders are produced. According to the orders that result due to this variation, determined test signal characteristics are compared with each other and/or with ideal signal characteristics with respect to their artifact behavior. A preferred order is determined from the resulting orders by taking into account the results of the comparison.

Abstract: A magnetic resonance fingerprinting (MRF) method for determining parameter values in pixels of an examination object can use a magnetic resonance system with, for example, a constant magnetic field strength (e.g. of less than 1.5 tesla or a constant magnetic field strength of less than 0.5 tesla). The MRF method can be adapted for conditions that prevail with such low-field magnetic resonance systems, thus enabling the parameter values to be advantageously determined efficiently while simultaneously maintaining a high degree of quality.

Abstract: In a parameter value determination method, parameter values are determined based on at least two previously determined most similar comparison signal curves. As a result, the parameters for determining can be determined with a resolution greater than the resolution, underlying the comparison signal curves, of the values of the parameters to be determined. Advantageously, the determination of the parameter values are not limited to the values of the comparison signal curves, in other words, are not limited to the lattice/grid of the dictionary.

Abstract: In a method and apparatus for determining parameter values in voxels of an examination object using magnetic resonance fingerprinting (MRF), a first signal comparison is made of signal characteristics of established voxel time series with first comparison signal characteristics. Further synthetic comparison signal characteristics are generated from the first comparison signal characteristics and values determined in the first signal comparison. The generated further comparison signal characteristics are used to perform a further signal comparison, with which values of at least a first and a second further parameter are determined. From the further comparison signal characteristics, a value of at least one further parameter is determined that could not necessarily already be determined in the first signal comparison.

Abstract: In a magnetic resonance fingerprinting method and apparatus for improved determination of local parameter values of an examination object, in which at least two signal comparisons of acquired picture element time series are carried out with comparison signal curves for determination of parameter values. A further (subsequent) signal comparison takes into account results of a preceding signal comparison. This multi-stage determination of parameter values allows an increase of the spatial resolution and the precision with which the parameter values can be determined.

Abstract: Techniques are disclosed for providing a first magnetic resonance fingerprinting dictionary using fingerprints having a first length. A transformation matrix is also utilized that is configured to shorten the fingerprints to a second length that is shorter than the first length. A second magnetic resonance fingerprinting dictionary may then be obtained by multiplying the first magnetic resonance fingerprinting dictionary with the transformation matrix, with the fingerprints of the magnetic resonance fingerprinting dictionary having the second length. This facilitates the storage of a MRF dictionary that takes up less storage space and decreases the time taken to perform scanning operations.

Abstract: In a magnetic resonance method and apparatus, each repetition of a multi-repetition scan, (a) an RF excitation pulse is applied to the subject under examination, (b) a slice-selection gradient is activated while the RF excitation pulse is being applied, (c) further gradients for spatial encoding are activated, and (d) measurement data are acquired as an echo signal produced after the RF excitation pulse. Steps (a) to (d) are repeated until a desired number of RF excitation pulses have been applied. An additional dedicated dephasing gradient is switched in each case such that a transverse magnetization of the spins to be excited by an RF excitation pulse is sufficiently dephased before each applied RF excitation pulse.

Abstract: In a method and magnetic resonance apparatus for generating a B0 map of a region of interest, a magnetic resonance data set containing a number of image data sets is obtained and provided in a computer, wherein the image data sets are recorded using at least two measurement sequences and the mutually corresponding pixels of the image data sets each represent a time-dependent signal evolution. A B0 map of the region of interest is generated by the computer from the image data sets, wherein the B0 value of a pixel of the B0 map is determined from the associated signal evolution.

Abstract: In a method and apparatus for magnetic resonance (MR) fingerprinting, an MR signal is acquired from a subject by radiating radio-frequency (RF) energy that produces an RF transmission field that has a localized amplitude in the subject. The RF energy is radiated with an RF pulse configuration that maps the localized RF field amplitude in the phase of the MR signal from the subject. The detected MR signal is compared to a source of stored MR signal physical or theoretical models that respectively map different localized RF transmission field information in the respective phase thereof, the stored models being respectively for different substances. A substance in the subject from which the detected MR signal curve originated is identified by comparing the detected MR signal curve to the stored models to identify a best match.

Abstract: In order to execute a low-artifact magnetic resonance fingerprinting (MRF) scan, a preferred order of N k-space trajectories of a sampling pattern is determined in a computer, along which in each case an undersampled scan data set is to be scanned, such that artifacts are avoided in parameter maps created from the scan data sets in an MRF scan. The order in which the N k-space trajectories are to be sampled one after the other is varied, so at least two different orders are produced. According to the orders that result due to this variation, determined test signal characteristics are compared with each other and/or with ideal signal characteristics with respect to their artifact behavior. A preferred order is determined from the resulting orders by taking into account the results of the comparison.

Abstract: In a method and apparatus for magnetic resonance (MR) fingerprinting, an MR signal is acquired from a subject by radiating radio-frequency (RF) energy that produces an RF transmission field that has a localized amplitude in the subject. The RF energy is radiated with an RF pulse configuration that maps the localized RF field amplitude in the phase of the MR signal from the subject. The detected MR signal is compared to a source of stored MR signal physical or theoretical models that respectively map different localized RF transmission field information in the respective phase thereof, the stored models being respectively for different substances. A substance in the subject from which the detected MR signal curve originated is identified by comparing the detected MR signal curve to the stored models to identify a best match.