50 results about "Diffusion weighting" patented technology

A method for performing motion correction in an autocalibrated, multi-shot diffusion-weighting MR imaging data acquisition includes performing motion correction on k-space data in an autocalibration region for each shot individually and then combining the motion-corrected k-space data from each shot to form a motion-corrected reference autocalibration region. Uncorrected source k-space data points are “trained to” the motion-corrected k-space data from the motion-corrected reference autocalibration region to determine coefficients that are used to synthesize motion-corrected k-space data in the outer, undersampled regions of k-space. Similarly, acquired k-space lines in the outer, undersampled regions of k-space may also be replaced by motion-corrected synthesized k-space data. The motion-corrected k-space data from the motion-corrected reference autocalibration region may be combined with the synthesized motion-corrected k-space data for the outer, undersampled regions of k-space to reconstruct motion-corrected images corresponding to each coil element. The motion corrected images corresponding to each coil element may be combined into a resultant image.

A method and a system for acquiring diffusion magnetic resonance images with compensation of the effects of eddy currents induced by the diffusion weighting (DW) gradient pulses. Prescan data are first acquired using the same DW sequence to be used for imaging. The prescan data are used to obtain eddy current parameters that model the effects of DW-induced eddy currents under the exact conditions under which DW images are to be acquired. The DW imaging sequence is then slightly modified according to the eddy current parameters and used to acquire DW image data with the effects of DW-induced eddy currents compensated.

The method and system for correcting motion-induced phase errors in Magnetic Resonance Imaging (MRI) use a phase shift of the non-phase encoded reference echo-signal accumulated during the diffusion-weighting in order to characterize bulk motion and tissue deformation and to compensate their effect for correcting the diffusion / perfusion-weighted image. The sequences unbalanced with respect to the first motion derivative are used for distinguishing the perfusion component. The MRI apparatus provides additional excitation resonance-frequency ranges for forming the reference echo signals.

Provided is a method of reducing distortions in a magnetic resonance diffusion imaging, comprising the steps of executing at least one first measurement (R1) having a first diffusion weighting, and executing at least one second measurement (R2) having a second diffusion weighting. A non-linear, system-specific distortion-correcting function is determined on the basis of system-specific information that is specific to the magnetic resonance data acquisition system. Correction parameters are calculated to correct distortions in subsequently-acquired diffusion-weighted magnetic resonance images, based on the data acquired in the first and second measurements with the system-specific distortion-correcting function applied thereto. The subsequently-acquired diffusion-weighted magnetic resonance images are corrected using the correction parameters to at least reduce distortions therein. A magnetic resonance system is also provided, and by means of the magnetic resonance system, the above method can be executed.

An imaging method for imaging a subject (18) including fibrous / anisotropic structures (102) includes acquiring three-dimensional image representations without and with a plurality of different diffusion weightings and directions. When a user (56) hovers a selection device over a voxel of the image, a fiber representation (54) is extracted in substantially real time. The representation is generated by following a direction of a major eigenvector e1 from voxel to voxel. A human-viewable display of the fiber representation is produced (210).

A method apparatus and computer product for imaging a human breast to map the breast ductal tree is disclosed. First, a breast is diffusion tensor imaged with high spatial resolution. Then the breast ductal tree is tracked using a protocol for breast based on echo-planar imaging (EPI) diffusion designed for optimizing diffusion weightings (b values), number of non-collinear directions for tensor calculations, diffusion, echo and repetition times, spatial resolution, signal to noise, scanning time and a sequence for fat suppression. The diffusion tensor is calculated by a non-linear best fit algorithm and then diagonalized with principal component analysis to three eigen vectors and their corresponding eigen values. A vector field map is obtained for tracking of breast ducts of the ductal trees along the direction of the 1st eigenvector v1 and the ductal tree is displayed on a voxel by voxel basis in parametric images using color coding and vector pointing.

Disclosed is a magnetic resonance method for the quantification of molecular diffusion. The method uses a diffusion-weighted (dw) double echo steady state sequence (DESS). In particular, the method allows direct quantification of molecular diffusion from two steady state scans with differing diffusion weighting such as one with diffusion-weighting and preferably one without diffusion weighting. Such a quantification of molecular diffusion allows for rapid and / or quantitative measurements of physiological and / or functional parameters of living tissue. Quantitative measurements are often a prerequisite for pre-clinical and clinical research as well as for clinical trials in drug research performed at different sites. Especially for the early diagnosis of subtle or diffuse pathological changes, quantitative MR promises to have a very significant impact.

A system detects malignant lymph nodes using an MR imaging device, for, in the absence of a contrast agent, acquiring in a patient anatomical volume of interest including lymph nodes, (a) a first image using a variable flip angle, lymph node enhanced contrast, MR image acquisition process, (b) a second image using a susceptibility weighting imaging acquisition process and (c) a third image using a diffusion weighting imaging acquisition process. In the presence of a contrast agent absorbed by benign lymph nodes, MR imaging device acquires in the patient anatomical volume of interest, (d) a fourth image using a susceptibility weighting imaging acquisition process. A display processor processes data representing the first, second, third and fourth images for display of malignant and benign lymph nodes on a reproduction device.

In a method and apparatus to reduce distortions in diffusion imaging, at least one first measurement is implemented with a first diffusion weighting for a number of slices that are spatially separated from one another and at least one second measurement is implemented with a second diffusion weighting for the number of slices that are spatially separated from one another. A deskewing function is determined as are correction parameters to deskew diffusion-weighted magnetic resonance images on the basis of the measurements, so that image information and / or correction parameters of different slices are linked with one another. The diffusion-weighted magnetic resonance images are distortion-corrected on the basis of the deskewing function and the correction parameters.

A method of acquiring T2-weighted and diffusion-weighted images is provided. The method includes acquiring a first image and a second image in a single magnetic resonance imaging (MRI) scan, where the first image and the second image have different echo times (TE). The single MRI scan includes a series of repeated RF excitation pulses, where the echo signal for the first image and the echo signal for the second image are acquired between a pair of RF excitation pulses. A spoiler gradient is disposed to provide a first diffusion weighting to the first image and a second diffusion weighting to the second image, where the first image and the second image have different T2 weightings and different diffusion weightings.