In general, according to the present embodiment, a magnetic resonance imaging apparatus includes sequence control circuitry and processing circuitry. The sequence control circuitry collects MR data corresponding to each of a plurality of echo times. The processing circuitry generates a plurality of magnitude images corresponding to the plurality of echo times based on the MR data. The processing circuitry generates a relaxation time map of tissue based on the plurality of magnitude images. The processing circuity generates a susceptibility map quantitatively indicating susceptibility values in a subject based on a magnetic field distribution that is generated based on a plurality of phase images corresponding to the plurality of echo times and the relaxation time map.

The present invention is directed to a system and method for reducing large magnetic artifact susceptibility in magnetic resonance imaging. The present invention is used to maximize cancellation of the magnetic field distortion cremated when objects with high variations in magnetic susceptibility are placed in a uniform magnetic field. Particularly, the present invention reduces the magnetic resonance imaging artifact produced by pacemakers and internal cardiac defibrillators in order to maximize the diagnostic image quality in the region surrounding these devices.

The invention provides for a magnetic resonance imaging system. Instructions cause a processor (136) controlling the magnetic resonance imaging system to modify (200) pulse sequence data by omitting at least some of the phase encodings (408) that encode for volumes outside of the field of view. The pulse sequence data specifies the acquisition of a stack (128) of two dimensional slices of a field of view (126). The pulse sequence data further specifies phase encoding in a direction (130) perpendicular to the two dimensional slices. The pulse sequence data specifies a maximum SEMAC factor (400). The maximum SEMAC factor specifies a maximum number of phase encoding steps in the perpendicular direction for each of the two dimensional slices. The instructions further cause the processor to determine (202) a slice SEMAC factor for each of the stack of two dimensional slices. The slice SEMAC factor is determined by counting the phase encoding steps that encode for regions within the field of view. The instructions further cause the processor to modify (204) the pulse sequence data by dividing the stack of two dimensional slices into multiple packages (502, 504). Slices within each of the multiple packages are ordered using an outer linear profile in the perpendicular direction. The stack of two dimensional slices are divided into the multiple packages by grouping slices which have a slice SEMAC factor within a predetermined range. Each of the multiple packages is acquired as a series of pulse sequence repetitions. The instructions further cause the processor to modify (206) the pulse sequence data by reordering the profile order of a package to remove at least some of the phase encodings outside of the field of view.

A magnetic resonance imaging (MRI) system can include a magnetic resonance imaging (MRI) scanner, having a plurality of radio frequency (RF) receivers, and a processor. The MRI scanner can perform a full field of view (fFOV) scan on an anatomy area including an implant to acquire first multi-spectral MRI data associated with a plurality of frequency bins. The processor can generate, for each pair of a single RF receiver and a single frequency bin, a respective spectral sensitivity map using at least a portion of the fFOV multi-spectral MRI data. The MRI scanner can perform a reduced FOV (rFOV) scan to acquire second multi-spectral MRI data associated with the plurality of frequency bins. The processor can reconstruct one or more MRI images according to the rFOV using the rFOV multi-spectral MRI data and the spectral sensitivity maps.

Described here are systems and methods for using a magnetic resonance imaging (MRI) system to estimate parameters of spectral profiles contained in multispectral data acquired using multispectral imaging (MSI) techniques, such as MAVRIC. These spectral profile parameters are reliably extracted using an iterative perturbation theory technique and utilized in a number of different applications, including fat suppression, artifact correction, and providing accelerated data acquisitions.

It is an object of the invention to improve quality assurance when using MRI images for radiotherapy treatment planning. This object is achieved by a treatment plan evaluation tool A configured for calculating a quality indicator for a radiotherapy treatment plan. The radiotherapy treatment plan originates from a planning image, wherein the planning image is an MRI image acquired under a presence of a main magnetic field having a magnetic field inhomogeneity. The treatment plan evaluation tool is further configured to receive information about the magnetic field inhomogeneity and the treatment plan evaluation tool is further configured to calculate the quality indicator based on the information about the magnetic field homogeneity.

In calculating a local magnetic field distribution caused by a magnetic susceptibility difference between living tissues, using MRI, a local frequency distribution with a high SNR is calculated in a short computation time. Multi-echo complex images obtained by measurement of at least two different echo times using the MRI are converted into low-resolution images. A global frequency distribution caused by global magnetic field changes and an offset phase distribution including a reception phase and a transmission phase are separated from a phase distribution of the low-resolution multi-echo complex images. Thus calculated global frequency distribution and the offset phase distribution are enhanced in resolution. A local frequency distribution of each echo is calculated from the measured multi-echo complex images, the high-resolution global frequency distribution, and the high-resolution offset phase distribution. The local frequency distributions of respective echoes are subjected to weighted averaging, whereby a final local frequency distribution is calculated.

To enable improved magnetic resonance imaging in the vicinity of an interference object that produces a magnetic interference field in an examination region, in a method and apparatus for magnetic resonance imaging of the examination region magnetic resonance raw data are acquired from the examination region by execution of a magnetic resonance sequence having multiple repetition intervals and refocusing of spins in the examination region at the end of each repetition interval repetition intervals. During at least part of the duration of the acquisition of the magnetic resonance raw data, a magnetic compensation gradient is activated that is opposed to the magnetic interference field.

In a method and apparatus for recording a magnetic resonance dataset of at least one foreign body in a target region of a patient, a magnetic resonance sequence having an ultra-short echo time, which is less than 500 s is used for recording the magnetic resonance data.

A system and method for imaging a subject includes a first imaging pulse sequence having gradient blips along an x-direction and a y-direction to acquire calibration image data from multiple slices. The imaging pulse sequence also includes a plurality of Z-shimming gradient blips coincident in time with the gradient blips along the x- and y-directions and varied within each slice. A plurality of calibration images are reconstructed from the calibration image data and a comparison image is formed by selecting an image from the calibration images corresponding to at least one of the varied Z-shimming gradient blips for each slice to determine a desired value of the Z-shimming gradient blips. The desired values are used to perform a second pulse sequence to acquire clinical image data from the subject. The second pulse sequence is used to acquire clinical images having been compensated for magnetic susceptibility variations within the subject.