Abstract: A magnetic resonance imaging system (200, 300) acquires magnetic resonance data (242, 244). A processor (230) controls the magnetic resonance imaging system to execute instructions (250, 252, 254, 256, 258) which cause the processor to repeatedly: control (100) the magnetic resonance imaging system to acquire magnetic resonance data including magnetic resonance navigator data (244); create (102) a set of navigator vectors by extracting the navigator data from each portion of the magnetic resonance data; construct (104) a dissimilarity matrix (246, 400, 700, 800, 900, 1000, 1100, 1400, 1500) by calculating a metric between each of the set of navigator vectors; generate (106) a matrix classification (248) of the dissimilarity matrix using a classification algorithm; and control (108) the magnetic resonance imaging system to modify acquisition of the magnetic resonance data using the matrix classification.

Abstract: The invention relates to a method of MR imaging of a body (10) of a patient. It is an object of the invention to provide a method that enables efficient compensation of flow artifacts, especially for MR angiography in combination with Dixon water/fat separation. The method of the invention comprises the steps of: a) generating MR echo signals at two or more echo times by subjecting the portion of the body (10) to a MR imaging sequence of RF pulses and switched magnetic field gradients, wherein the MR imaging sequence is a Dixon sequence; b) acquiring the MR echo signals; c) reconstructing one or more single-echo MR images from the MR echo signals; d) segmenting the blood vessels from the MR images; e) detecting and compensating for blood flow-induced variations of the amplitude or phase in the single-echo MR images within the blood vessel lumen, and f) separating signal contributions from water and fat spins to the compensated single-echo MR images.

Abstract: At least two gradient echo signals are generated at two different echo times by subjecting a portion of a body (10) in an MR examination region (1) to an imaging sequence of RF pulses and switched magnetic field gradients. The 0th moment of the readout magnetic field gradient essentially vanishes at the time of a first gradient echo while the 1st moment of the readout gradient is non-zero. Both the 0th and 1st moments of the readout magnetic field gradient essentially vanish at a time of a second gradient echo. Gradient echo signals are acquired. Acquiring the gradient echo signals is repeated for a plurality of phase encoding steps. A first MR image is reconstructed from the gradient echo signals of the first gradient echo and a second MR image is reconstructed from the gradient echo signals of the second gradient echo. Ghosting artefacts in the first and/or second MR image are identified by comparing the first and second MR images.

Abstract: The invention relates to a method of MR imaging of at least a portion of a body (10) of a patient placed in an examination volume of a MR device (1), the method comprising the steps of: —subjecting the portion of the body (10) to a first imaging sequence for acquiring a first signal data set (21); —subjecting the portion of the body (10) to a second imaging sequence for acquiring a second signal data set (23), wherein the imaging parameters of the second imaging sequence differ from the imaging parameters of the first imaging sequence; —reconstructing a MR image from the second signal data set (23) by means of regularization using the first signal data set (21) as prior information. Moreover, the invention relates to a MR device (1) and to a computer program for a MR device (1).

Abstract: A black blood magnetic resonance imaging sequence is performed using a magnetic resonance scanner. The sequence includes: applying a first flow sensitization gradient; applying a spoiler gradient after applying the first flow sensitization gradient; applying a second flow sensitization gradient after applying the spoiler gradient wherein the second flow sensitization gradient has area equal to the first flow sensitization gradient but of opposite polarity; applying a slice-selective radio frequency excitation pulse after applying the spoiler gradient; and performing a magnetic resonance readout after applying the second flow sensitization gradient and after applying the slice selective radio frequency excitation. The readout acquires magnetic resonance imaging data having blood signal suppression in the region excited by the slice-selective radio frequency excitation pulse. The magnetic resonance imaging data is suitably reconstructed to generate a black blood image that may be displayed.

Abstract: Interleaved black/bright imaging (IBBI) is performed using a magnetic resonance (MR) scanner wherein the black blood module of the IBBI includes: applying a first flow sensitization gradient; applying a spoiler gradient after applying the first flow sensitization gradient; applying a second flow sensitization gradient after applying the spoiler gradient wherein the second flow sensitization gradient has area equal to the first flow sensitization gradient but of opposite polarity; applying a slice selective radio frequency excitation pulse after applying the spoiler gradient; and performing a MR readout after applying the second flow sensitization gradient and after applying the slice selective radio frequency excitation wherein the readout acquires MR imaging data having blood signal suppression in the region excited by the slice selective radio frequency excitation pulse.

Abstract: The invention provides for a magnetic resonance imaging system (200, 300) for acquiring magnetic resonance data (242, 244). A processor (230) for controlling the magnetic resonance imaging system executes instructions (250, 252, 254, 256, 258) which cause the processor to repeatedly: control (100) the magnetic resonance imaging system to acquire a portion of the magnetic resonance data, wherein each portion of the magnetic resonance data comprises navigator data (244); create (102) a set of navigator vectors by extracting the navigator data from each portion of the magnetic resonance data; construct (104) a dissimilarity matrix (246, 400, 700, 800, 900, 1000, 1100, 1400, 1500) by calculating a metric between each of the set of navigator vectors; generate (106) a matrix classification (248) of the dissimilarity matrix using a classification algorithm; and control (108) the magnetic resonance imaging system to modify acquisition of the magnetic resonance data using the matrix classification.

Abstract: The invention relates to a method of MR imaging of a body (10) placed in the examination volume of a MR device (1). It is an object of the invention to provide a method that enables efficient compensation of flow artefacts, especially for contrast-enhanced MR angiography in combination with Dixon water/fat separation.

Abstract: A black blood magnetic resonance imaging sequence is performed using a magnetic resonance scanner. The sequence includes: applying a first flow sensitization gradient; applying a spoiler gradient after applying the first flow sensitization gradient; applying a second flow sensitization gradient after applying the spoiler gradient wherein the second flow sensitization gradient has area equal to the first flow sensitization gradient but of opposite polarity; applying a slice-selective radio frequency excitation pulse after applying the spoiler gradient; and performing a magnetic resonance readout after applying the second flow sensitization gradient and after applying the slice selective radio frequency excitation. The readout acquires magnetic resonance imaging data having blood signal suppression in the region excited by the slice-selective radio frequency excitation pulse. The magnetic resonance imaging data is suitably reconstructed to generate a black blood image that may be displayed.

Abstract: Interleaved black/bright imaging (IBBI) is performed using a magnetic resonance (MR) scanner (10) wherein the black blood module (52) of the IBBI includes: applying a first flow sensitization gradient; applying a spoiler gradient after applying the first flow sensitization gradient; applying a second flow sensitization gradient after applying the spoiler gradient wherein the second flow sensitization gradient has area equal to the first flow sensitation gradient but of opposite polarity; applying a slice selective radio frequency excitation pulse after applying the spoiler gradient; and performing a MR readout after applying the second flow sensitization gradient and after applying the slice selective radio frequency excitation wherein the readout acquires MR imaging data having blood signal suppression in the region excited by the slice selective radio frequency excitation pulse.

Abstract: A method for generating an MR image of an object situated in an examination volume of an MR apparatus begins with the acquisition of a plurality of echo signals having at least two different echo-time values (t1, t2, t3). The echo signals are generated from high-frequency pulses and magnetic-field gradient pulses by an imaging sequence. An intermediate MR image (5, 6, 7) is then reconstructed for each echo-time value (t1, t2, t3). By analyzing these intermediate MR images (5, 6, 7), local relaxation times (T2*(x)) and/or local frequency shifts (??(x)) are determined by taking account of the respective echo-time values (t1, t2, t3). Finally, a definitive MR image (11) is reconstructed from the echo signals (1) in their entirety.

Abstract: An MR device for MR imaging includes an RF coil system. In order to enable switching to and fro between different applications in such an MR device without having to move the patient so as to position a new RF coil system, it is proposed to provide the RF coil system for the transmission and/or reception of RF signals with at least two RF coil arrays which are integrated in one coil former and have been optimized for different applications, each RF coil array comprising at least two RF coils which are decoupled from one another.

Abstract: The invention relates to an MR method in which a navigator pulse is generated to excite a nuclear magnetization in a spatially limited volume by at least one RF pulse and at least two gradient magnetic fields having gradients which extend differently in respect of time and space. After the navigator pulse excitation, at least one MR signal is received from the volume in conjunction with a further gradient magnetic field for evaluation. In order to enhance the navigator pulse, a variation in time is imposed on the gradient magnetic fields in order to generate at least two MR signals which correspond to an excitation in the k space along mutually offset trajectories. The MR signals are combined.

Abstract: The invention relates to an MR method in which a navigator pulse is generated to excite a nuclear magnetization in a spatially limited volume by at least one RF pulse and at least two gradient magnetic fields having gradients which extend differently in respect of time and space. After the navigator pulse excitation, at least one MR signal is received from the volume in conjunction with a further gradient magnetic field for evaluation. In order to enhance the navigator pulse, a variation in time is imposed on the gradient magnetic fields in order to generate at least two MR signals which correspond to an excitation in the k space along mutually offset trajectories. The MR signals are combined.

Abstract: A magnetic resonance imaging method is proposed wherein a magnetic resonance image is reconstructed from magnetic resonance signals from respective signal channels. More specifically, individual signal channels relate to respective surface coils which are employed as receiver antennas for the magnetic resonance signals. The magnetic resonance signals are acquired with sub-sampling of the k-space. Resampling on a regular square grid is performed, thus enabling fast Fourier transformation in the reconstruction of the magnetic resonance image. Furthermore, the reconstruction is carried out on the basis of the spatial sensitivity profile of the receiver antennas, i.e. of the surface coils, so as to separate contributions from different spatial positions in the sub-sampled magnetic resonance signals. Preferably, a spiral-shaped acquisition trajectory is followed in the k-space.