Abstract: The invention provides for a medical imaging system (100, 300). The medical imaging system (100, 300) comprises a processor (104).

Abstract: The invention relates to a method of MR imaging of an object (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 motion-compensation and/or motion-correction and that is compatible with Cartesian sampling of k-space. The method of the invention comprises: —generating MR signals by subjecting the object (10) to a MR imaging sequence of at least one RF pulse and switched magnetic field gradients; —acquiring the MR signals as a plurality of temporally successive subsets, each subset comprising a number of k-space profiles with sub-sampling of k-space, wherein the subsets complement each other to form a fully sampled set of k-space profiles; —reconstructing a single-subset MR image from each subset; —computing a gradient MR image from each single-subset MR image; and —detecting motion by comparing the gradient MR images with each other. Moreover, the invention relates to a MR device (1) and to a computer program for a MR device (1).

Abstract: The present invention pertains to magnetic resonance imaging, notably of separate body parts with open space between them. A bridge member containing MR responsive material is provided in the open space to establish a correspondence between the body parts. The MR responsive material generates magnetic resonance signals in response the RF excitation, so that between the separate body parts via the bridge member magnetic resonance signal are obtained from positions between which there is at most a limited spatial variation of the main magnetic field, so that phase ambiguities between the signals from these positions are avoided. Thus chemical shift separation, notably water-fat separation though a region-of-interest containing several (both) body parts may rely on a smoothness condition imposed on the spatial distribution of the main magnetic field. This avoids artefacts, such as water-fat swaps when separating water and fat contributions in the reconstructed magnetic resonance image.

Abstract: The invention relates to a method of magnetic resonance (MR) imaging of an object positioned in an examination volume of a MR device. One aspect of the invention provides a method that enables parallel imaging in combination with fat suppression at an increased image quality, notably in combination with EPI. The method includes: acquiring reference MR signal data from the object in a pre-scan, acquiring imaging MR signal data from the object in parallel via one or more receiving coils having different spatial sensitivity profiles, wherein the MR signal data are acquired with sub-sampling of k-space and with spectral fat suppression, and reconstructing an MR image from the imaging MR signal data, wherein sub-sampling artefacts are eliminated using sensitivity maps indicating the spatial sensitivity profiles of the two or more RF receiving coils. A B0 map is derived from the reference MR signal data and the spatial dependence of the effectivity of the spectral fat suppression is determined using the B0 map.

Abstract: A method of parallel MR imaging includes subjecting the portion of the body (10) to an imaging sequence of at least one RF pulse and a plurality of switched magnetic field gradients. The MR signals are acquired in parallel via a plurality of RF coils (11, 12, 13) having different spatial sensitivity profiles within the examination volume. The method further includes deriving an estimated ghost level map from the acquired MR signals and from spatial sensitivity maps of the RF coils (11, 12, 13), and reconstructing a MR image from the acquired MR signals, the spatial sensitivity maps, and the estimated ghost level map.

Abstract: The invention provides for a magnetic resonance imaging system (200, 300, 400) comprising a radio-frequency system (216, 214) comprising multiple coil elements (214) for acquiring magnetic resonance data (264). The magnetic resonance imaging system further comprises a memory (250) for storing machine executable instructions (260) and pulse sequence commands (262). The pulse sequence commands are configured for controlling the magnetic resonance imaging system to acquire the magnetic resonance data according to a SENSE imaging protocol. The magnetic resonance imaging system further comprises a processor (244) for controlling the magnetic resonance imaging system.

Abstract: The invention relates to a method of MR imaging. It is an object of the invention to provide a Dixon water/fat separation technique—in particular in combination with a single-point acquisition scheme—that avoids swaps of water and fat signals in the reconstructed MR images due to imperfections of the main magnetic field Bo. The method of the invention comprises the following steps: —generating and acquiring echo signals in a pre-scan by subjecting an object (10) to a first imaging sequence; —deriving a fat fraction map from the echo signals of the pre-scan; —generating and acquiring echo signals in a clinical scan by subjecting the object (10) to a second imaging sequence; —deriving a field map estimate from the fat fraction map and from the echo signals of the clinical scan; —reconstructing a MR image from the echo signals of the clinical scan, wherein signal contributions from fat and water are separated on the basis of the field map estimate.

Abstract: The invention provides for a magnetic resonance imaging system (100) configured for acquiring magnetic resonance data (142) from an imaging zone (108) according to a PROPELLER magnetic resonance imaging protocol. The pulse sequence is configured such that the pulse sequence data for each of the multiple blades of magnetic resonance data comprises coil specific magnetic resonance data (145, 146?, 146?, 146??) acquired for each of multiple antenna elements simultaneously (125, 126?, 126?, 126??). The magnetic resonance imaging system is further configured to perform the following for each blade: reconstruct (214) a blade image (150, 150?) from the coil specific magnetic resonance data for each antenna element according to a parallel imaging magnetic resonance imaging protocol, construct (218) a Chi map (153, 154?) for the blade image using the set of coil sensitivities, the blade image, and the coil specific magnetic resonance data.

Abstract: The invention relates to a method of MR imaging near metal parts using SEMAC. It is an object of the invention to provide an improved MR imaging technique that is sufficiently fast and robust against susceptibility effects. The invention proposes to apply a weaker slice-selection magnetic field gradient (Gslice) for reduction of ripple-artefacts near metal parts or to apply undersampling in the slice-selection direction of the SEMAC sequence or to apply both these aspects. According to one aspect of the invention, a sparsity constraint is used to make the reconstruction of the undersampled MR images more stable. Moreover, the invention relates to a MR device (1) and to a computer program to be run on a MR device (1).

Abstract: A method of MR imaging includes acquiring reference MR signal data from the object (10); deriving a B0 map from the reference MR signal data; adapting sensitivity maps according to the B0 map, which sensitivity maps indicate spatial sensitivity profiles of one or more RF receiving coils (11, 12, 13), to correct for geometric distortions of the sensitivity maps; acquiring imaging MR signal data from the object (10) via the one or more receiving coils (11, 12, 13) with sub-sampling of k-space; and reconstructing a MR image from the imaging MR signal data. Sub-sampling artifacts are eliminated using the adapted sensitivity maps. The reference MR signal data are acquired using a multi-point Dixon technique. A water image and a fat image are reconstructed from the imaging MR signal data using separate water and fat sensitivity maps. The water and fat images are preferably reconstructed using regularized SENSE.

Abstract: The invention relates to a method of parallel MR imaging. The method comprises the steps of: a) subjecting the portion of the body (10) to an imaging sequence of at least one RF pulse and a plurality of switched magnetic field gradients, wherein MR signals are acquired in parallel via a plurality of RF coils (11, 12, 13) having different spatial sensitivity profiles within the examination volume, b) deriving an estimated ghost level map from the acquired MR signals and from spatial sensitivity maps of the RF coils (11, 12, 13), c) reconstructing a MR image from the acquired MR signals, the spatial sensitivity maps, and the estimated ghost level map. Moreover, the invention relates to a MR device (1) and to a computer program for a MR device (1).

Abstract: The invention relates to a method of MR imaging of an object (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 motion-compensation and/or motion-correction and that is compatible with Cartesian sampling of k-space. The method of the invention comprises: —generating MR signals by subjecting the object (10) to a MR imaging sequence of at least one RF pulse and switched magnetic field gradients; —acquiring the MR signals as a plurality of temporally successive subsets, each subset comprising a number of k-space profiles with sub-sampling of k-space, wherein the subsets complement each other to form a fully sampled set of k-space profiles; —reconstructing a single-subset MR image from each subset; —computing a gradient MR image from each single-subset MR image; and —detecting motion by comparing the gradient MR images with each other. Moreover, the invention relates to a MR device (1) and to a computer program for a MR device (1).

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 image artefacts in combination with PROPELLER imaging. The invention proposes to combine k-space blades in image space, and not in k-space like in conventional PROPELLER imaging. Local image artefacts are detected and corrected in single-blade MR images. The artefact detection and correction in the image domain prior to combining the single-blade MR images into a final MR image results in an improved image quality by better suppression of local artefacts and, thus, an increased signal-to-noise. Moreover, the invention relates to a MR device (1) and to a computer program for a MR device (1).

Abstract: The invention provides for a magnetic resonance imaging system (100) configured for acquiring magnetic resonance data (142) from an imaging zone (108) according to a PROPELLER magnetic resonance imaging protocol. The pulse sequence is configured such that the pulse sequence data for each of the multiple blades of magnetic resonance data comprises coil specific magnetic resonance data (146, 146?, 146?, 146??) acquired for each of multiple antenna elements simultaneously (126, 126?, 126?, 126??). The magnetic resonance imaging system is further configured to perform the following for each blade: reconstruct (214) a blade image (150, 150?) from the coil specific magnetic resonance data for each antenna element according to a parallel imaging magnetic resonance imaging protocol, construct (218) a Chi map (154, 154?) for the blade image using the set of coil sensitivities, the blade image, and the coil specific magnetic resonance data.

Abstract: The invention relates to a method of MR imaging of an object positioned in an examination volume of a MR device (1). The method comprises the steps of: acquiring reference MR signal data from the object (10); deriving a Bo map from the reference MR signal data; adapting sensitivity maps according to the B0 map, which sensitivity maps indicate spatial sensitivity profiles of one or more RF receiving coils (11, 12, 13), to correct for geometric distortions of the sensitivity maps; acquiring imaging MR signal data from the object (10) via the one or more receiving coils (11, 12, 13) with sub-sampling of k-space; and reconstructing a MR image from the imaging MR signal data, wherein sub-sampling artefacts are eliminated using the adapted sensitivity maps. In a preferred embodiment, the reference MR signal data are acquired using a multi-point Dixon technique, wherein a water map and a fat map are derived from the reference MR signal data.

Abstract: The invention relates to a method of MR imaging near metal parts using SEMAC. It is an object of the invention to provide an improved MR imaging technique that is sufficiently fast and robust against susceptibility effects. The invention proposes to apply a weaker slice-selection magnetic field gradient (Gslice) for reduction of ripple-artefacts near metal parts or to apply undersampling in the slice-selection direction of the SEMAC sequence or to apply both these aspects. According to one aspect of the invention, a sparsity constraint is used to make the reconstruction of the undersampled MR images more stable. Moreover, the invention relates to a MR device (1) and to a computer program to be run on a MR device (1).

Abstract: The invention relates to a transmitter-receiver system comprising at least three transmitters and at least a first receiver and a second receiver, wherein the receivers are connected to a computing device that is arranged to analyse signals that said receivers receive from said transmitters and to calculate length and attitude information of an imaginary baseline connecting said receivers depending on at least carrier phase information of said signals using interval analysis.