It is proposed a method for post-processing images of an region of interest in a subject, the images being acquired with a magnetic resonance imaging technique, the method for post-processing comprising at least the step of:unwrapping the phase of each image,extracting a complex signal over echo time for at least one pixel of the unwrapped images, andcalculating fat characterization parameters by using a fitting technique applied on a model, the model being a function which associates to a plurality of parameters each extracted complex signal, the plurality of parameters comprising at least two fat characterization parameters, the magnitude error and the phase error generated by the use of the bipolar readout gradients, the fitting technique being a non-linear least-square fitting technique using pseudo-random initial conditions.

According to one embodiment, a magnetic resonance imaging apparatus includes a data acquiring unit and a data processing unit. The data acquiring unit is configured to acquire magnetic resonance signals according to an imaging condition for applying a first off-resonance radio frequency pulse after an application of an excitation pulse and before a readout of the magnetic resonance signals, and applying a second off-resonance radio frequency pulse after the readout of the magnetic resonance signals and before an application of a following excitation pulse. The first off-resonance radio frequency pulse generates a phase shift in the magnetic resonance signals. The second off-resonance radio frequency pulse compensates the phase shift. The data processing unit is configured to obtain information to be obtained by data processing of the magnetic resonance signals.

A method for 3D oscillating-gradient prepared gradient spin-echo imaging and a device. The imaging method comprises the following steps: first, using a global saturation module to destroy previous residual transverse magnetization; second, embedding a pair of trapezoidal cosine oscillating gradients into a 90.sub.x-180.sub.y-90.sub.x radiofrequency pulse by a diffusion encoding module, to separate diffusion encoding from signal acquisition; then, using a fat saturation module to suppress a fat signal; finally, acquiring a signal by means of gradient spin-echo readout, and correcting phase errors among multiple excitations by multiplexed sensitivity-encoding reconstruction. Compared with a 2D plane echo-based oscillating gradient diffusion sequence used on a 3T clinical system, a 3D oscillating-gradient prepared gradient spin-echo sequence effectively reduces the imaging time, improves the signal to noise ratio, and is beneficial to clinical transformation of time-dependent diffusion MRI technology.

The disclosure provides a modified EPI sequence for acquiring multi-shot and multi-echo images with interleaved blip-up and blip-down phase encoding; the blip-up and blip-down images are processed by topup in FSL to estimate the inhomogeneous main magnetic field B.sub.0 map that causes image distortions; the B.sub.0 map is then incorporated into the encoding matrix with a low rank constraint to form a joint reconstruction model; the joint reconstruction model is solved to obtain multiple distortion-free images; and the multiple distortion-free images are matched to dictionary to simultaneous acquire the quantitative T.sub.2(=1/R.sub.2) and T.sub.2*(=1/R.sub.2*) maps. In the phantom and in-vivo measurements, the disclosed method rapidly acquires the comparable quantitative images within one hold-breath (for 20 s) to the conventional mapping method, thus providing important practical application value for evaluation of liver damage, iron level and cancer lesion.

A magnetic resonance imaging (MRI) apparatus for obtaining a magnetic resonance (MR) image using a multi-echo pulse sequence including a plurality of repetition times, including a memory configured to store an MR signal obtained using the multi-echo pulse sequence, and an image processor configured to determine a plurality of echo times included in the plurality of repetition times to provide the multi-echo pulse sequence including the plurality of echo times during the plurality of repetition times, and to obtain the MR image, based on the MR signal, wherein the plurality of repetition times includes a first repetition time adjacent to a second repetition time, wherein the plurality of echo times includes a first echo time of the first repetition time, a second echo time of the first repetition time, a first echo time of the second repetition time, and a second echo time of the second repetition time.

Methods and systems to obtain and apply T.sub.2 preparatory radiofrequency (RF) pulse sequences for magnetic resonance imaging (MRI) are provided. The iterative methods may employ propagation of the magnetization state of the object being imaged and a comparison with a target magnetization state. The methods disclosed may be used to obtain MRI pulse sequences that may optimize T.sub.2 relaxation contrast. The produced RF pulse sequences may be robust to effects from inhomogeneity of the magnetic fields or other environmental or physiological perturbations.

Methods for imaging magnetic resonance imaging (MRI) agents containing nanoconstructs therein using diffusion-weighted fast-spin echo (FSE) or gradient-and-spin echo (GRASE) processes are described herein.

The present invention is directed to a system and method for determining blood volume in a subject. Blood volume is an important hemodynamic parameter for monitoring many disorders, such as stoke and cancer. Current MRI techniques for quantification of absolute blood volume for such clinical applications all require injecting exogenous contrast agents. To reduce associated safety risks and cost, the present invention is directed to a non-contrast-enhanced MRI method for blood volume mapping on MRI. The technique of the present invention employs velocity-selective (VS) pulse trains in paired control and label modules for separating vascular signal by subtraction. The Fourier-transform based VS saturation pulse train (FT-VSS) of the present invention has improved performance over conventional VS pulse trains for the blood volume measurement.

A method for imaging a subject using a magnetic resonance imaging (MRI) system includes determining a tailored radio frequency (RF) pulse sequence having a plurality of refocusing pulses. In the method, a target peak RF pulse value is determined and a transfer function to convert a first refocusing pulse of the plurality of refocusing pulses to a modified refocusing pulse with the target peak RF pulse value is also determined. A modified RF pulse sequence is generated based on the transfer function and the plurality of refocusing pulses. Finally, magnetic resonance (MR) signals from the subject are acquired based on the modified RF pulse sequence and the medical image of the subject is generated based on the acquired MR signals.

The invention relates to a method of MR imaging of at least an object (10) placed in an examination volume of a MR device (1). It is an object of the invention to enable fast MR imaging using a multi-echo imaging technique which is robust with respect to motion. The method of the invention comprises the steps of:generating echo signals by subjecting the object (10) to an imaging sequence,acquiring the echo signals, each echo signal being attributed to a k-space line, wherein a number of k-space lines, which are adjacently arranged in a part of k-space, are repeatedly sampled, with said number of k-space lines being sampled in a different sequential order per repetition, andreconstructing a MR image from the acquired echo signals. Moreover, the invention relates to a MR device for carrying out this method as well as to a computer program to be run on a MR device.