Abstract: A magnetic resonance sequence includes a repetitively applied radiofrequency pulse capable of causing a specific absorption rate (SAR) hot spot. The composition of the repetitive pulse is varied to generate versions of the repetitive pulse such that the SAR hot spot changes locations with subsequent applications of the repetitive pulse. To generate versions of the pulse, a pilot scan is performed to generate a patient model. A simulation of the SAR response to each of the versions of the repetitive pulse is performed to determine the location of SAR hot spot(s). A plurality of versions of the repetitive pulse is selected to be used in the magnetic resonance sequence.

Abstract: The present invention relates to a magnetic resonance imaging MRI system (100) for acquiring magnetic resonance data from a target volume in a subject (118), the magnetic resonance imaging system (100) comprises: a memory (136) for storing machine executable instructions; and a processor (130) for controlling the MRI system (100), wherein execution of the machine executable instructions causes the processor (130) to: determine an energy distribution (301-305) over a k-space domain of the target volume; receive a reduction factor representing a degree of under-sampling of the k-space domain; derive from the energy distribution (301-305) and the received reduction factor a sampling density function; derive from the sampling density function an energy dependent sampling pattern of the k-space domain; control the MRI system (100) to acquire under-sampled k-space data using a pulse sequence that samples the k-space domain along the derived sampling pattern; apply a compressed sensing reconstruction to the acquired

Abstract: A combined magnetic resonance (MR) and radiation therapy system includes a bore-type magnet with a magnet radiation translucent region which allows radiation beams to travel radially through the magnet and a split-type gradient coil includes a gradient coil radiation translucent region aligned to the magnet radiation translucent region. A radiation source, disposed laterally to the magnet, administers a radiation dose through the magnet and gradient coil radiation translucent regions to an examination region. A dosage unit determines the actual radiation dose delivered to each voxel of a target volume and at least one non-target volume based on a pre-treatment, intra-treatment, and/or post-treatment image representation of the target volume and the at least one non-target volume. A planning processor updates at least one remaining radiation dose of a radiation therapy plan based on the determined actual radiation dose.

Abstract: A parallel magnetic resonance imaging system (1) includes at least one radio frequency (RF) coil (10, 12) with a plurality of coil elements, a smart select unit (24), a parallel imaging parameter unit (28), and a sequence control (16). The smart select unit (24), from a pre-scan or prior scan of a subject with the at least one RF coil, constructs (60) a signal map and a plurality of noise maps based on different sets of reduction factors. The parallel imaging parameter unit (28) selects a set of reduction factors corresponding to a noise map which includes a highest signal-to-noise ratio (SNR). The sequence control (16) performs a magnetic resonance imaging scan of the subject based on the selected reduction factors.

Abstract: A combined magnetic resonance (MR) and radiation therapy system (10) includes a bore-type magnet (12) with a magnet radiation translucent region (16) which allows radiation beams to travel radially through the magnet and a split-type gradient coil (18) includes a gradient coil radiation translucent region (20) aligned to the magnet radiation translucent region (16). A radiation source (24), disposed laterally to the magnet, administers a radiation dose through the magnet and gradient coil radiation translucent regions (16, 20) to an examination region (14). A dosage unit (66) determines the actual radiation dose delivered to each voxel of a target volume (30) and at least one non-target volume based on a pre-treatment, intra-treatment, and/or post-treatment image representation of the target volume (30) and the at least one non-target volume. A planning processor (60) updates at least one remaining radiation dose of a radiation therapy plan based on the determined actual radiation dose.

Abstract: A magnetic resonance system (10),and corresponding method, image a subject using a conversion-free interleaved black and bright blood imaging (cfIBBI) sequence. A MR scanner (12) is controlled to perform a plurality of repetitions of a black blood imaging sequence (52). The black blood imaging sequence (52) includes a tissue nulling sub-sequence followed by a black blood acquisition sub-sequence (56) performed a time interval (TI) after the tissue nulling sub-sequence. The MR scanner (12) is further controlled to, between successive repetitions of the black blood imaging sequence (52), perform a bright blood imaging sequence (54) including the tissue nulling sub-sequence followed by a bright blood acquisition sub-sequence (58) performed the time interval (TI) after the tissue nulling sub-sequence. The time intervals (TI) of the black blood imaging sequence (52) and the bright blood imaging sequence (54) are of the same duration.

Abstract: The present invention relates to a magnetic resonance imaging MRI system (100) for acquiring magnetic resonance data from a target volume in a subject (101), the magnetic resonance imaging system (100) comprising: a plurality of excitation means (201) for generating a slice-/or slab-selective spatial radio frequency RF excitation magnetic field targeting slice/slab spatial variations in the target volume, and a controller (219) coupled to the plurality of excitation means (201), wherein the controller (219) is adapted for: determining a power level required by the plurality of excitation means (201) for generating the slice-/or slab-selective spatial RF excitation magnetic field, decomposing the slice-/or slab-selective spatial RF excitation magnetic field into respective RF excitation constituents of the plurality of excitation means (201), controlling each of the plurality of excitation means (201) to simultaneously generate the respective RF excitation constituent, using the determined power level for acqu

Abstract: The invention relates to a method of parallel MR imaging, wherein a reference scan is performed by means of a stimulated echo sequence including i) at least two preparation RF pulses (a) radiated toward a portion of a body (10) during a preparation period (21), and ii) one or more reading RF pulses 03) radiated toward the portion of the body (10) during an acquisition period (22) temporally subsequent to the preparation period (21). One or more FID signals (I1) and one or more stimulated echo signals (I2) are acquired during the acquisition period (22). The spatial receive and/or—if applicable—transmit4 sensitivity profiles of at least two RF coils (11, 12, 13) are derived from the acquired FID signals (I1) and/or from the acquired stimulated echo signals (I2). The parameters of the stimulated echo sequence are selected such that it is robust against susceptibility-induced artefacts. Moreover, 10 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 (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, wherein a portion of a body (10) placed in the examination volume of a MR device (1) is subjected to an imaging sequence (IMG) of RF pulses and switched magnetic field gradients. The imaging sequence (IMG) is a stimulated echo sequence including i) at least two preparation RF pulses (?) radiated toward the portion of the body (10) during a preparation period (21), and ii) one or more reading RF pulses (?) radiated toward the portion of the body (10) during an acquisition period (22) temporally subsequent to the preparation period (21). One or more FID signals (I1) and one or more stimulated echo signals (I2) are acquired during the acquisition period (22). A B1 map indicating the spatial distribution of the RF field of the RF pulses within the portion of the body (10) is derived from the acquired FID (I1) and stimulated echo (I2) signals.

Abstract: The present invention relates to a method of performing dynamic contrast enhanced magnetic resonance imaging of an object (10) with signal separation for water and fat, the method comprising acquiring magnetic resonance datasets in the k-space using Dixon acquisition in a chemical shift encoding space and dynamic time resolution in a dynamic time space, wherein the dataset acquisition is performed employing undersampling, wherein the method further comprises: applying a compressed sensing reconstruction technique in the k-space, the chemical shift encoding space and the dynamic time space, said compressed sensing reconstruction resulting in reconstructed datasets, —performing Dixon reconstruction on the reconstructed datasets and dynamic contrast analysis on the Dixon reconstructed datasets.

Abstract: In a method and apparatus to enable increased RF duty cycle in high field MR scans, a specific energy absorption rate (SAR) calculation processor calculates the local and global SAR or even a spatial SAR map. By incorporating additional information as, e.g. patient position, the SAR calculation accuracy can be increased as well as by using more patient specific pre-calculated information (e.g. based on different bio meshes), the so called Q-matrices. A sequence controller maybe provided to create a global SAR optimal RF pulse. After the optimal RF pulse is applied, the SAR and its spatial distribution are determined. SAR hotspots are also determined. Q-matrices within an appropriate radius around the hotspots are averaged and added to a global Q-matrix in a weighted fashion. After the global Q-matrix is updated, a new optimal RF pulse is created.

Abstract: A multi nuclei RF antenna arrangement for use in a multi nuclei MRI system or an MR scanner, for transmitting RF excitation signals (B1 field) for exciting nuclear magnetic resonances (NMR), and/or for receiving NMR relaxation signals for multi nuclei MR (magnetic resonance) image reconstruction is disclosed, wherein the RF antenna arrangement is tuned to the Larmor frequencies of at least two different species of nuclei having at least two different gyromagnetic rations like 1H, 14N, 31P, 13C, 23Na, 39K, 17O and hyper polarized gases like 129Xe or other isotopes having a nuclear spin. Further, a method for reconstructing a multi nuclei MR image especially by means of the above RF antenna arrangement is disclosed. The method involves reducing back-folding artifacts of the species having the higher gyromagnetic ration by parallel MRI reconstruction.

Abstract: The invention relates to a method of MR imaging, wherein a portion of a body placed in the examination volume of an MR device is subjected to an imaging sequence of RF pulses and switched magnetic field gradients. The imaging sequence is a stimulated echo sequence including i) two preparation RF pulses (?) radiated toward the portion of the body during a preparation period (21), and ii) reading RF pulses (?) radiated toward the portion of the body during an acquisition period (22) temporally subsequent to the preparation period (21). FID signals (I1) and stimulated echo signals I2) are acquired during the acquisition period (22) with equal T2*-weighting. A B1 map indicating the spatial distribution of the RF field of the preparation RF pulses within the portion of the body is derived from the acquired FID (I1) and stimulated echo (I2) signals.

Abstract: A medical imaging system (5) includes one or more processors and a display device (36). The one or more processors are programmed to receive (60) a first image (10) contrasting regions of tissue with a distinct radiotracer accumulation probability and generate (64) a constraint map (20) based on the regions of tissue with the distinct radiotracer accumulation probability. The one or more processors are programmed to reconstruct (70) a second image (44) with redistribution of a measured radiotracer based on the constraint map (20) and acquired image raw data (23) registered to the constraint map. The display device (36) displays the reconstructed second image.

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: When generating an MR image using a multi-channel transmit coil arrangement, SAR is reduced by employing a number of different RF pulses in a single scan. Each RF pulse exhibits a different performance and/or accuracy, resulting in different RF pulse-specific SAR values. As a result, the RF pulses differ slightly in actual excitation pattern, B1 waveform and/or k-space trajectory, etc. The average SAR over a single scan is thus reduced compared to a fixed RF pulse, without compromising image quality.

Abstract: An apparatus includes a magnetic resonance imaging system, a processor for controlling the apparatus, and a memory containing machine executable instructions and a pulse sequence. The machine executable instructions and pulse sequence cause the processor to control the apparatus to: acquire magnetic resonance data from an imaging volume, wherein the magnetic resonance data includes gradient echo data; segment the magnetic resonance data into a plurality of segments, the segments including a fat segment, a water segment, a cortical bone segment, and an air segment; and create a bulk density map of the imaging volume from the segments.

Abstract: A method comprises: performing a number of B i field mapping sequences (24) using a set of radio frequency transmit coils (11) to acquire a B1 field mapping data set wherein said number is less than a number of radio frequency transmit coils in the set of radio frequency transmit coils; and determining coil sensitivities (30) for the set of radio frequency transmit coils based on the acquired B1 field mapping data set. In some embodiments, the performed B1 field mapping sequences are defined by (i) performing a linear transform (40) on the set of radio frequency transmit coils to generate a set of orthogonal virtual radio frequency transmit coils (42) and (ii) selecting (44) a sub-set (46) of the set of orthogonal virtual radio frequency transmit coils that define the performed B1 field mapping sequences.

Abstract: The invention relates to a method of acquiring MRI image data comprising the following steps: performing a 3-dimensional B1 mapping of a first volume using a first voxel size, selecting an MRI protocol, performing the B1-shim in accordance with the MRI protocol, performing the MRI protocol to acquire MRI imaging data of a second volume using a second voxel size, wherein the first voxel size is larger than the second voxel size, wherein the first volume is larger than the second volume, and wherein the second volume is contained within the first volume.