Magnetic Resonance Imaging (MRI), which is given the acronym ULTRA (Unlimited Trains of Radio Acquisitions), can eliminate magnetic gradient reversals and allow simultaneous MR signal acquisition from the entire object volume in each of a multitude of very small receiver coils arranged in a 3D array around the imaging volume, except for gradient reversals and/or RF pulses for refocusing spins into echoes. This permits a rate of MR signal acquisition that is greatly increased (e.g. 256 times) compared with existing techniques, with a full 3D image constructed in as little as 1 millisecond. Furthermore, noiseboth audible and electricalis substantially reduced. The advantages over conventional MRI include: 1. Clinical imaging can be completed in seconds or less, with good signal-to-noise ratio; 2. Signal-to-noise ratio further increased by reducing or eliminating RF noise due to gradient switching; 3. Real-time functional MRI on millisecond timescales; 4. With single breath holds, high quality imaging of thorax and abdomen. 5. Greatly reduced audible noise and vibration.

The present invention relate to a system and associate method of MRI and MR spectroscopy which provide stable measurements of the relaxation times, T1 and T2, by using tailored multi-band RF pulses that direct control of the saturation conditions in the background pool of macro-molecular protons, and hence provide a flexible means to induce constant Magnetisation Transfer (MT) effects. In doing this, equal saturation of the background pool is obtained for all measurements independent of the parameters that may be changed, for example, the rotation rate used to obtain a desired flip angle, that is, the degree of change in the magnetisation of the free pool of protons.

Methods and apparatus for operating a low-field magnetic resonance imaging (MRI) system to perform diffusion weighted imaging, the low-field MRI system including a plurality of magnetics components including a B.sub.0 magnet configured to produce a low-field main magnetic field B.sub.0, at least one gradient coil configured to, when operated, provide spatial encoding of emitted magnetic resonance signals, and at least one radio frequency (RF) component configured to acquire, when operated, the emitted magnetic resonance signals. The method comprises controlling one or more of the plurality of magnetics components in accordance with at least one pulse sequence having a diffusion-weighted gradient encoding period followed by multiple echo periods during which magnetic resonance signals are produced and detected, wherein at least two of the multiple echo periods correspond to respective encoded echoes having an opposite gradient polarity.

A computer-implemented method of building a database of pulse sequences for parallel-transmission magnetic resonance imaging, includes a) for each of a plurality of subjects, determining an optimal sequence for the subject; b) for each subject, computing the values of the or of a different cost or merit function obtained by playing the optimal sequences for all the subjects; c) aggregating the subjects into a plurality of clusters using a clustering algorithm taking the values, or functions thereof, as metrics; d) for each cluster, determining an averaged optimal sequence for the cluster; e) receiving, as input, a set of features characterizing an imaging subject, comprising at least a morphological feature of the subject; f) associating the subject to one pulse sequence of the database based on the set of features using the computer-implemented classifier algorithm; and g) performing magnetic resonance imaging using the pulse sequence. A magnetic resonance imaging apparatus for carrying out steps e)-g) of such a method is also provided.

A method for magnetic resonance imaging (MRI) comprises applying a consecutive series of MRI sequences to a target volume (V) according to experimental settings (TR, ?, ?). A discrete sequence of transient response signals (Sn, Sn+1, Sn+2) is measured and fitted to a fit function (F) that is continuously dependent on a sequence number (n) of the respective MRI sequence (Pn) and corresponding response signal (Sn). A shape of the fit function is determined according to an analytically modelled evolution by the experimental parameters (TR, ?, ?) as well as variable intrinsic parameters (r, ?3, ?, ?) to be fitted. For example, the model is based on an equivalent harmonic oscillator. The intrinsic parameters of the fit function can be related to the intrinsic properties (PD, T1, T2) of the spin systems and used for imaging the target volume (V). Various optimizations of contrast can be achieved by tuning the experimental settings according to the model.

A dark blood magnetic resonance imaging (MRI) imaging technique utilizes a time-reversed steady-state free precession (SSFP) pulse sequence, in which magnetic field gradients are unbalanced along at least one gradient axis, but balanced along at least one of the other gradient axes. The pulse sequence can include interrupted shots, in which subsequent shots or repetitions of the pulse sequence are not continuous in time. For example, the pulse sequence can be gated based on cardiac signals, respiratory signals, or navigator data, or may be otherwise discontinuous over time.

A method for acquiring magnetic resonance imaging data from a subject. The method includes performing a series of radio frequency pulses formed of individual RF pulses applied with a constant time interval between each of the individual RF pulses to form a consistent magnetic field about at least of a region of interest in the subject, where the RF pulse has a flip angle of less than 30 degrees. The method also includes performing phase encoding gradients to achieve spatial encoding and performing an imaging acquisition process over an acquisition window to acquire imaging data. The method further includes performing phase encoding rephasing gradients and repeating the preceding steps such that a time between a center of the acquisition window and a center of a first RF pulse in a first RF pulse in a repetition of the RF pulses is equal to the constant pulse interval.

A system and method for controlling a magnetic resonance imaging (MRI) system to create magnetic resonance (MR) cine angiograms of a subject. The method includes controlling the MRI system to acquire MR data from the subject by performing at least one cine acquisition pulse sequence having a plurality of acquisition RF pulse modules applied at constant intervals throughout a cardiac cycle, and at least one labeling pulse sequence including a first and a second /2 module and a labeling RF pulse module for labeling a region of inflowing arterial flow through a vessel of interest. The method further includes reconstructing the MR data to form a series of cine frames that form a cine angiogram, subtracting at least one cine frame from other cine frames reconstructed from the MR data, and displaying the MR cine angiogram of the vessel of interest.

In a magnetic resonance method and apparatus, each repetition of a multi-repetition scan, (a) an RF excitation pulse is applied to the subject under examination, (b) a slice-selection gradient is activated while the RF excitation pulse is being applied, (c) further gradients for spatial encoding are activated, and (d) measurement data are acquired as an echo signal produced after the RF excitation pulse. Steps (a) to (d) are repeated until a desired number of RF excitation pulses have been applied. An additional dedicated dephasing gradient is switched in each case such that a transverse magnetization of the spins to be excited by an RF excitation pulse is sufficiently dephased before each applied RF excitation pulse.

A method for quantifying T1, T2 and resonance frequency simultaneously using magnetic resonance fingerprinting (MRF) includes accessing an MRF dictionary using a magnetic resonance imaging (MRI) system. The MRF dictionary is generated by simulating signal evolutions that include associated off-resonance effects for each signal evolution. The method further includes acquiring MRF data from a region of interest in a subject using the MRI system and a MRF pulse sequence having a plurality of radio frequency (RF) excitations and a readout associated with each RF excitation. Each readout includes a plurality of segments and each segment is used to generate a time frame. The method also include comparing the MRF data to the MRF dictionary to identify a plurality of parameters including T1, T2 and resonance frequency for the MRF data and generating a report indicating the at least one of the plurality of parameters of the MRF data.