The present invention provides a magnetic resonance imaging system for imaging a subject by a multi-shot imaging. The magnetic resonance imaging system comprises an acquiring unit for acquiring MR raw data corresponding to a plurality of shots; an imaging unit for generating a plurality of folded images from the MR raw data, wherein each of the plurality of folded images is generated from a subset of the MR raw data; a deriving unit for deriving magnitude of each pixel of each folded image; a detecting unit for detecting a motion of the subject during the multi-shot imaging based on similarity measurements of any two folded images of the plurality of folded images, wherein the detecting unit further comprises a first deriving unit configured to derive the measured similarities; and a reconstructing unit for reconstructing a MR image of the subject based on MR raw data obtained according to a detection result of the detecting unit. Since the partially acquired MR raw data is used for motion detection directly, it would be more rapid and stable.

The disclosure relates to magnetic resonance imaging triggered by a prospective acquisition correction sequence. The technique comprises determining repetition time and an acquisition window time of a single-shot fast spin echo sequence; determining the maximum imaging layer number N in each physiological movement cycle on the basis of the acquisition window time and the repetition time, where N is a positive integer greater than or equal to 2; and enabling the single-shot fast spin echo sequence to obtain M layers of imaging data within at least one acquisition window time when the prospective acquisition correction sequence generates a trigger signal, where M is a positive integer greater than or equal to 2 and less than or equal to N. According to the present disclosure, a plurality of layers of imaging data are obtained within a single acquisition window time, thereby increasing a scanning speed and shortening imaging time.

The present invention provides a magnetic resonance imaging system for imaging a subject by a multi-shot imaging. The magnetic resonance imaging system comprises an acquiring unit for acquiring MR raw data corresponding to a plurality of shots; an imaging unit for generating a plurality of folded images from the MR raw data, wherein each of the plurality of folded images is generated from a subset of the MR raw data; a deriving unit for deriving magnitude of each pixel of each folded image; a detecting unit for detecting a motion of the subject during the multi-shot imaging based on similarity measurements of any two folded images of the plurality of folded images, wherein the detecting unit further comprises a first deriving unit configured to derive the measured similarities; and a reconstructing unit for reconstructing a MR image of the subject based on MR raw data obtained according to a detection result of the detecting unit. Since the partially acquired MR raw data is used for motion detection directly, it would be more rapid and stable.

In one embodiment, a magnetic resonance imaging apparatus includes memory circuitry configured to store a predetermined program; and processing circuitry configured, by executing the predetermined program, to set an FSE type pulse sequence in which an excitation pulse is followed by a plurality of refocusing pulses, the plurality of the refocusing being divided into at least a first pulse group subsequent to the excitation pulse and a second pulse group subsequent to the first pulse group, the first pulse group including refocusing pulses having a predetermined high flip angle, and the second pulse group including refocusing pulses having flip angles decreased from the predetermined high flip angle toward a flip angle of zero, and generate an image of an object from respective MR signals corresponding to the plurality of refocusing pulses acquired by applying the fast spin echo type pulse sequence to the object.

In a method and system, a reference dataset is recorded using a reference scan based on a GRE or RA RT sequence. A correction dataset is also recorded using a phase correction scan based on a non-phase-encoding EPI sequence. A measurement dataset is recorded using an SMS sequence. Slice-specific GRAPPA kernels are determined from the reference dataset and magnetic resonance images are created by a slice GRAPPA method. Data of the measurement dataset belonging to different slices is separated from one another using the slice-specific GRAPPA kernels and N/2 ghost artifacts are corrected using the correction dataset.

Provided herein is technology relating to magnetic resonance imaging contrast agents and particularly, but not exclusively, to methods and systems for visualizing one or more magnetic resonance imaging contrast agent.

In a method to associate k-space lines with echo trains of raw magnetic resonance data, parallel k-space lines orthogonally intersect a plane at respective intersection points. Each echo train has a trajectory length, and the k-space lines are associated with the echo trains such that a sum of trajectory lengths of all echo trains is minimal. The trajectory length TL of an echo train is defined by $\mathrm{TL}=\underset{i=1}{\overset{L-1}{.Math.}}\stackrel{\_}{P_i{P}_{i+1}}$
wherein L is a sequence of k-space lines, P.sub.i is an intersection point of the i-th k-space line of the echo train with the plane; and P.sub.iP.sub.i+1 is the length of the path from the i-th intersection point to the (i+1)-th intersection point.

In a method and magnetic resonance (MR) system to acquire MR data in a predetermined volume segment of an examination subject, the data are acquired with at least one echo train that includes at least two signal echoes. The same number of echoes is acquired for each echo train of the at least one echo train, with this number of echoes corresponding to an echo train length. The total number of echoes that are required to acquire the MR data and the echo train length is adapted so that the total number corresponds to a whole number multiple of the echo train length.

A magnetic resonance imaging protocol includes an acquisition segment to control an acquisition sequence to acquire magnetic resonance signals at a lower main magnetic field strength. A reconstruction segment controls reconstruction of a diagnostic magnetic resonance image from the magnetic resonance signals at a lower main magnetic field strength. A segmentation segment to control segmentation of a pre-determined image-detail of the diagnostic magnetic resonance image. In the magnetic resonance imaging protocol: the acquisition sequence has a set of imaging parameters that cause the image quality of the diagnostic magnetic resonance to be similar to the image quality of the magnetic resonance training images. The segmentation segment comprises: an initialisation portion which controls (i) access to a set of magnetic resonance training images acquired at main magnetic field of a higher main magnetic field strength (ii) registration of the diagnostic magnetic resonance image to one or more of the magnetic resonance training images and (iii) a segmentation proper applied to the diagnostic image to segment the pre-determined detail from the registered diagnostic magnetic resonance image. The one or more magnetic resonance training images includes an image detail corresponding to the pre-determined image detail in the diagnostic magnetic resonance image. Notably, the magnetic resonance training magnetic resonance images are acquired at a high magnetic field strength at 7 T and its level of detail facilitates the accurate segmentation of notably the hippocampus from diagnostic magnetic resonance images at lower field strength of 3 T. The diagnostic magnetic resonance images are acquired such that they resemble the training magnetic resonance images.

A magnetic resonance imaging (MRI) apparatus, including a radio frequency (RF) transmitter configured to transmit a plurality of excitation RF pulses to an object, and to transmit a refocusing RF pulse to the object within a repetition time (TR) period after transmitting the plurality of excitation RF pulses; and a controller configured to control the RF transmitter to transmit a plurality of first additional gradient magnetic fields corresponding to the plurality of excitation RF pulses in order to spoil a plurality of free induction decay (FID) signals produced by the plurality of excitation RF pulses, and to transmit a plurality of second additional gradient magnetic fields corresponding to the plurality of excitation RF pulses in order to generate a plurality of spin echo signals corresponding to the spoiled plurality of FID signals; and an RF receiver configured to acquire the generated plurality of spin echo signals.