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.

Described here are systems and methods for reconstructing images from multi-level sampled data acquired with a magnetic resonance imaging (MRI) system. An alternating direction method-of multipliers (ADMM) strategy is implemented for sparse reconstruction of multi-level sampled data, and which decomposes the reconstruction problem into simpler subproblems and enables certain operations to be computed once offline and recycled during the reconstruction process rather than repeated at every iteration. As one example, the described reconstruction technique enables sparse reconstruction of 3D contrast-enhanced MR angiogram time-series in just several minutes rather than the several hours previously required.

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.

Described here are systems and methods for generating quantitative perfusion parameter maps based on different longitudinal relaxation parameter maps that are produced from images acquired using non-selective and selective magnetic resonance imaging (“MRI”) data acquisition techniques.

Method of determining a velocity profile of a fluid flowing through a conduit, the method including applying a saturation pulse on spins of magnetic field-sensitive nuclei in the fluid, measuring a signal of the fluid to determine position of the magnetic field-sensitive nuclei, the measurement carried out at a recovery time ‘TR’ and at a distance ‘d’ within the conduit, determining within the conduit a radial distance ‘r’ characterized by a local minimum in the measured signal, wherein the radial distance ‘r’ is measured from the center of the conduit, and determining a velocity profile of the fluid at the radial distance, based on the magnetic field-sensitive nuclei.

A method for measuring the flow rate of a multi-phase medium flowing through a measuring tube using a nuclear magnetic resonance flow meter can be used to measure the flow rate of a multi-phase medium in a simplified manner. For this purpose, a measuring device is used which implements, at the end of each pre-magnetization path, 2D tomography in the measurement tube cross-sectional plane with stratification in the z direction; the measurement tube cross-sectional plane is subdivided into layers that are thin compared to the measurement tube diameter; nuclear magnetic resonance measurements are carried out in every layer to determine measurement signals, using pre-magnetization paths of different lengths; the flow rates are measured in every layer based on the measurement signals; and the time is determined from the signal ratios of the amplitudes of the measurement signals in every layer.

A method is for performing an angiographic measurement of a main measurement region of a patient via a magnetic resonance system. An embodiment of the method includes performing at least one overview measurement to generate overview-measurement data; defining, using the overview-measurement data, the main measurement region and a first measurement region, the first measurement region differing from the main measurement region; performing a first time-resolved measurement in the first measurement region defined to generate first time-resolved measurement data; detecting an injected contrast agent bolus in the first measurement region using the first time-resolved measurement data; determining a flow rate of the injected contrast agent bolus detected; setting at least one measurement parameter of the angiographic measurement according to the flow rate determined; and performing the angiographic measurement of the main measurement region of the patient in the magnetic resonance system using the at least one measurement parameter set.

A method for determining a pulse duration T.sub.90 of a 90° pulse in a nuclear magnetic measuring method. A signal generator has a known generator resistance R.sub.S, wherein a coil has a coil impedance Z.sub.L with a coil resistance R.sub.L and a coil reactance X.sub.L, wherein a coupling circuit has an adjustable matching capacitance C.sub.M and an adjustable tuning capacitance C.sub.T, and wherein the medium has a Larmor precession having an angular Larmor frequency ω.sub.P. The time needed for determining the pulse duration T.sub.90 of the 90° pulse is reduced by the matching capacitance C.sub.M and the tuning capacitance C.sub.T being set so that the angular resonance frequency ω.sub.0 corresponds to the angular Larmor frequency ω.sub.P and by power matching being present between the signal generator and the coil. The coil resistance R.sub.L is determined and the pulse duration T.sub.90 is determined as a function of the coil resistance R.sub.L.

To provide an imaging technique suitable for acquiring an image with reduced artifacts due to differences in signal intensity. An MR apparatus 100 acquires, in data acquisition periods A1, A2, and A3, data at part of grid points lying closer to a high-frequency region RH within a low-frequency region RL, and data at part of grid points lying closer to the low-frequency region RL within the high-frequency region RH. On the other hand, in a data acquisition period B, it acquires data at another part of grid points lying closer to the high-frequency region RH within the low-frequency region RL, and data at another part of grid points lying closer to the low-frequency region RL within the high-frequency region RH.

A method for creating a first MRI image and a second MRI image is provided. A first echo is read out. A second echo is read out. The first echo readout is used to generate a first image set, with each image pixel being a first linear combination of the first species and the second species. The second echo readout is used to generate a second image set, with each image pixel being a second linear combination of the first species and the second species. The first image set and second image set are combined to obtain a first combined image containing only the first species and a second combined image containing only the second species, comprising combining the first image set and the second image set to generate two pairs of solutions and using a mathematical optimization to choose a correct pair of solutions.