Koninklijke Philips Corporation N.V.

Elwin De Weerdt

Miha Fuderer

Johannes Martinus Peeters

Nicola Pezzotti

Johan Samuel Van Den Brink

Jochen Keupp

Johan Michiel Den Harder

Michel Paul Jurriaan Jurrissen

Zhaolin Chen

Gerrit Hendrik Van Ijperen

Jean-Pierre Franciscus Alexander Maria Ermes

Giuseppe Valvano

Ulrike Andrea Blume

Steven Koppelman

Adriaan Leendert Moerland

Jochen Keup

The invention relates to a magnetic resonance imaging system (). The magnetic resonance imaging system () comprises a memory () and a processor (). The memory () stores machine executable instructions (), first pulse sequence commands () and second pulse sequence commands (). Execution of the machine executable instructions () by the processor () causing the processor () to control the magnetic resonance imaging system () to acquire identifying magnetic resonance data () using the first pulse sequence commands (). The identifying magnetic resonance data () identifies on a per voxel basis, whether the respective voxel is water or fat dominated. Imaging magnetic resonance data () is acquired using the second pulse sequence commands (). A magnetic resonance image () is reconstructed using the imaging magnetic resonance data (). The identifying magnetic resonance data () is used to determine on a per voxel basis, whether the imaging magnetic resonance data () used for the reconstruction is dominantly induced by water or fat.

MRI with fat/water separation

The present disclosure relates to a method comprising: providing a trained machine learning model. The trained machine learning model is configured for reconstructing images from input data. The method comprises: receiving () a multidimensional array comprising M dimensional acquired data; determining () a subset of values of at least one K selected dimension of the array; for each value of the subset determining () a M−K dimensional array comprising the acquired data corresponding to the value, resulting in a set of M−1 dimensional arrays; inputting () the set of M−K dimensional arrays to the trained machine learning model, and receive a reconstructed image from the trained machine learning model.

Adaptive reconstruction of magnetic resonance images

Disclosed herein is a medical system () comprising: a memory () storing machine executable instructions () and a processor (). Execution of the machine executable instructions causes the processor to: receive () magnetic resonance imaging data (), wherein the magnetic resonance imaging data has a spiral k-space sampling pattern; reconstruct () at least one preliminary magnetic resonance image () from the magnetic resonance imaging data; construct () a first set of equations comprising () each of the at least one preliminary magnetic resonance image being equal to an image transformation of at least one clinical image, wherein the image transformation makes use of a first spatially dependent kernel for each of the at least one clinical image (″); construct () a second set of equations () comprising at least one regularization matrix (″) times the at least one clinical image; and numerically () solve the first set of equations and the second set of equations simultaneously for the at least one clinical image.

Reconstruction of spiral k-space sampled magnetic resonance images

Disclosed is a medical imaging system (). The execution of machine executable instructions () causes a processor () to: receive () measured magnetic resonance imaging data () descriptive of a first region of interest () of a subject (); receive () a B0 map (), a T1 map (), a T2 map (), and a magnetization map () each descriptive of a second region of interest () of the subject; receive () pulse sequence commands (); calculate () a simulated magnetic resonance image () of an overlapping region of interest () using at least the B0 map, the T1 map, the T2 map, the magnetization map, and the pulse sequence commands as input to a Bloch equation model (); and reconstruct () a corrected magnetic resonance image from the measured magnetic resonance imaging data for the overlapping region of interest by solving an inverse problem. The inverse problem comprises an optimization of a cost function and a regularization term formed from the simulated magnetic resonance image.

Correction of magnetic resonance images using simulated magnetic resonance images

A fat suppressed diffusion image determination apparatus, a corresponding method and a corresponding computer program determine a diffusion weighted magnetic resonance image (DWI) of an object. The fat suppressed diffusion image determination apparatus includes a diffusion reference image providing unit for providing a diffusion reference MR image of the object, a fat image determination unit for determining a fat image from the diffusion reference MR image, a diffusion weighted image providing unit for providing a diffusion weighted MR image of the object, a fat suppressed image determination unit for determining a fat suppressed diffusion weighted MR image using a combination of the diffusion weighted MR image and the fat image.

Diffusion MR imaging with fat suppression

The invention relates to a method of MR imaging of an object () positioned in an examination volume of a MR device (). It is an object of the invention to enable fast spiral MR imaging with a defined T2 contrast. The method of the invention comprises the following steps: &#x2014;generating a number of spin echoes by subjecting the object () to one or 5 more shots of an imaging sequence, each shot comprising an RF excitation pulse () followed by a number of RF refocusing pulses (), wherein modulated readout magnetic field gradients () are applied in each interval between successive RF refocusing pulses (), &#x2014;acquiring MR signal data, wherein each spin echo is recorded along a spiral trajectory (--) in k-space which winds around the k-space origin with varying radial distance, wherein the trajectory () of at least one spin echo has a different rate of variation of the radial distance at least in a central k-space region compared to the trajectories () of the other spin echoes, and&#x2014;reconstructing an MR image from the acquired MR signal data. Moreover, the invention relates to an MR device () and to a computer program for an MR device ().

Multi-echo MR imaging with spiral acquisition

A method of medical imaging including receiving k-space data that is divided into multiple k-space data groups, selecting one of the multiple k-space data groups as a reference k-space data group, and calculating spatial transform data for each of the multiple k-space data groups by inputting the multiple k-space data groups and the reference k-space data group into a transformation estimation module. The spatial transformation estimation module is configured for outputting spatial transform data descriptive of a spatial transform between a reference k-space data group and multiple k-space data groups in response to receiving the reference k-space data group and the multiple k-space data groups as input. The method further comprises reconstructing a corrected magnetic resonance image according to the magnetic resonance imaging protocol using the multiple k-space data groups and the spatial transform data for each of the multiple k-space data groups.

Motion estimation and correction in magnetic resonance imaging

A medical imaging system includes a memory for storing machine executable instructions. The medical imaging system further includes a processor for controlling the medical imaging system. Execution of the machine executable instructions causes the processor to: receive magnetic resonance image data acquired according to a CEST magnetic resonance imaging protocol, wherein the magnetic resonance image data includes voxels, wherein each of the voxels includes a measured Z-spectrum for a set of saturation frequency offsets; assign a motion likelihood map to each voxel by comparing the measured Z-spectrum of each voxel to predetermined criteria; and reconstruct a CEST magnetic resonance image using the magnetic resonance image data and the motion likelihood map.

Motion detection in CEST magnetic resonance imaging based on Z-spectrum analysis

The invention provides for a medical imaging system (). The medical imaging system () comprises a processor (). Execution of machine executable instructions () causes the processor () to: receive magnetic resonance data, wherein the magnetic resonance data comprises B0 field data () of a reference scan for a plurality of voxels and water saturation data () of a WASSR scan for a subset of voxels of the plurality of voxels, the water saturation data () comprising data of a limited number of sample points; determine a local absolute water saturation frequency () for each voxel of the subset using the water saturation data () of the WASSR scan; and reconstruct a field map () comprising a local absolute water saturation frequency for each voxel of the plurality of voxels, wherein the reconstruction comprises determining relative frequency differences between the voxels using the B0 field data () of the reference scan and adding a frequency offset to the relative frequency differences based on the determined local absolute water saturation frequencies () of the subset.

MRI method for determining a magnetic field map from a B0 reference scan and a WASSR scan

A bridge member containing MR responsive material is provided in an open space between body parts 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.

Bridge member for a magnetic resonance examination system

A magnetic resonance imaging system () includes a radio-frequency system () with multiple coil elements () for acquiring magnetic resonance data () and a memory () for storing machine executable instructions () and pulse sequence commands (). 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. Execution of the machine executable instructions causes a processor () to: control () the magnetic resonance imaging system to acquire the magnetic resonance data using the pulse sequence commands; reconstruct () a set of folded magnetic resonance images () from the magnetic resonance data; calculate () a voxel deformation map () from a magnetic field inhomogeneity map; and calculate () a set of unfolding matrices () using a least partially a coil sensitivity matrix () for the multiple coil elements, wherein the set of unfolding matrices includes at least one modified unfolding matrix which is calculated at least partially using the a coil sensitivity matrix and the voxel deformation map. Undistorted magnetic resonance image data () is calculated () using the set of folded magnetic resonance images and the set of unfolding matrices.

BO-corrected sensitivity encoding magnetic resonance imaging

A magnetic resonance (MR) imaging technique 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 and acquiring imaging MR signal data from the object in parallel via one or more receiving coils having different spatial sensitivity profiles. The MR signal data are acquired with sub-sampling of k-space and with spectral fat suppression and an MR image is reconstructed from the imaging MR signal data. Sub-sampling artefacts are eliminated using sensitivity maps indicating the spatial sensitivity profiles of the two or more RF receiving coils. A Bmap is derived from the reference MR signal data and the spatial dependence of the effectivity of the spectral fat suppression is determined using the Bo map. In the image reconstruction step, signal contributions from water and fat are separated using regularisation taking the spatial dependence of the effectivity of the spectral fat suppression into account.

Parallel MR imaging with spectral fat suppression

A Dixon water/fat separation technique, in particular in combination with a single-point acquisition scheme, avoids swaps of water and fat signals in the reconstructed MR images due to imperfections of the main magnetic field B. Echo signals are generated and acquired in a pre-scan by subjecting an object () to a two or more point imaging sequence. A fat fraction map is derived from the echo signals of the pre-scan. Echo signals are generated and acquired in a clinical scan by subjecting the object () to a single-point imaging sequence. A field map estimate is derived from the fat fraction map and from the echo signals of the clinical scan. An MR image is reconstructed from the echo signals of the clinical scan. Signal contributions from fat and water are separated on the basis of the field map estimate.

MR imaging with dixon-type water/fat separation

The invention relates to a method of MR imaging of an object () placed in the examination volume of a MR device (). 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: &#x2014;generating MR signals by subjecting the object () to a MR imaging sequence of at least one RF pulse and switched magnetic field gradients; &#x2014;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; &#x2014;reconstructing a single-subset MR image from each subset; &#x2014;computing a gradient MR image from each single-subset MR image; and &#x2014;detecting motion by comparing the gradient MR images with each other. Moreover, the invention relates to a MR device () and to a computer program for a MR device ().

MR imaging with motion detection

A method of parallel MR imaging includes subjecting the portion of the body () 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 () 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 (), and reconstructing a MR image from the acquired MR signals, the spatial sensitivity maps, and the estimated ghost level map.

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Tilburg, Netherlands

Elwin De Weerdt