48 results about "Diffusion weighting" patented technology

The invention discloses a fast-diffused magnetic resonance imaging and restoring method. The method comprises the following steps: (S1) conducting signal collection to a detected target in N diffusion weighting directions through a plurality of channel coils; (S2) merging the obtained complementary k space data so as to obtain fully-sampled k space data KC; (S3) conducting primary restoration based on images of different diffusion weighting directions corresponding to the k space data and images corresponding to the fully-sampled k space data KC so as to obtain a primary image; and (S4) conducting regularization restoration based on the primary image, iterating to convergence so as to obtain the final needed images (I1,....IN). The description gives a specific realization mode of the method. Common information among images in different diffusion weighting directions are utilized, so that not only the sampling efficiency is improved, but also the resolution and signal to noise ratio of the images can be enhanced.

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 weighting 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 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.

In a method and magnetic resonance apparatus to reduce distortions in magnetic resonance diffusion imaging, a magnetic resonance data acquisition system is operated to acquire magnetic resonance data in a first measurement with a first diffusion weighting, and to acquire magnetic resonance data in a second measurement with a second, different diffusion weighting. A non-linear, system-specific distortion-correcting function is determined on the basis of system-specific information that is specific to said 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.

The invention discloses a multi-b-value DWI (diffusion weighted image) noise reduction method based on mutual information. The method comprises steps as follows: acquiring to-be-tested multi-b-value DWIs in multiple diffusion sensitive gradient directions by a magnetic resonance scanner; performing preprocessing such as head movement correction, eddy current correction and the like on the images; estimating different b-value image signal-to-noise ratios; performing noise reduction processing on the images through setting parameters of an optimal noise reduction algorithm so as to acquire DWIs with higher signal-to-noise ratios. The method fully considers features of different images, and three-dimensional structural features of the processed images are reserved as many as possible while noises are eliminated. During establishment of a high-order complex model, different b images have higher image quality, so that acquired high-order parameter images can have smaller errors and fewer singular values. The method can be better applied to preprocessing of a high-order model imaging technology and plays an active role in further research on white matter fiber structures.

In a method and magnetic resonance apparatus for correction of image distortions that occur in acquisition of diffusion-weighted magnetic resonance images of an examination subject, a reference image is acquired without diffusion weighting, a first diffusion-weighted image is acquired for a diffusion direction, a second diffusion-weighted image is acquired for the same diffusion direction, with the acquisition of the second diffusion-weighted image taking place at least with a different diffusion weighting or a different diffusion gradient polarity than the acquisition of the first diffusion-weighted image. Distortion parameters for the correction of image distortions in the acquired diffusion-weighted images are acquired, and the first diffusion-weighted image is deskewed with a first set of deskewing parameters, and the second diffusion-weighted image is deskewed with a second set of deskewing parameters. The first set and second set of deskewing parameters are correlated, and the deskewing parameters are determined by simultaneous minimization of differences between the deskewed first image and the reference image and differentiation between the deskewed second image and the reference image.

In a method and magnetic resonance (MR) system for correction of image distortions that occur in acquisitions of diffusion-weighted MR images of an examination subject a first adjustment measurement with a first diffusion weighting is implemented, a second adjustment measurement with a second diffusion weighting is implemented and correction parameters to de-skew diffusion-weighted MR images are automatically calculated in a computer on the basis of the two adjustment measurements. One of the two adjustment measurements is implemented with a predetermined diffusion weighting in three orthogonal diffusion directions, and correction parameters are determined for the three orthogonal diffusion directions.

In a method for correction of distortions in image data in a diffusion imaging, the image data are acquired with an imaging MRT measurement for a predetermined diffusion weighting and map a predetermined image segment. A diffusion model for the image segment is determined. Output image data are determined for the image segment such that the output image data are essentially free of distortions caused by diffusion weighting. Reference image data are estimated for the predetermined diffusion weighting for the image segment based on the output image data and the diffusion model. The acquired image data are compared with the reference image data and the acquired image data are corrected based on the comparison.

A method, system, computer-readable medium, use, and pulse sequence for magnetic resonance imaging or nuclear magnetic resonance is provided for determining the rate of molecular exchange between components with different diffusion characteristics. The present invention encodes the magnetic resonance signal for exchange utilizing judiciously designed protocols for varying the parameters of a pulse sequence comprising a pair of diffusion weighting blocks separated by a mixing time.

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.

The present invention describes a method for quantifying microscopic diffusion anisotropy and/or mean diffusivity in a material by analysis of echo attenuation curves acquired with two different gradient modulations schemes, wherein one gradient modulation scheme is based on isotropic diffusion weighting and the other gradient modulation scheme is based on non-isotropic diffusion weighting, and wherein the method comprises analyzing by comparing the signal decays of the two acquired echo attenuation curves.

The present invention describes a method for magnetic resonance (MR) and/or MR imaging, comprising acquisition of signals and MR images originating from a RF and gradient sequence causing isotropic diffusion weighting of signal attenuation, wherein the isotropic diffusion weighting is achieved by one time-dependent dephasing vector q(t) having an orientation, wherein the isotropic diffusion weighting is proportional to the trace of a diffusion tensor D, and wherein the orientation of the time-dependent dephasing vector q(t) is either varied discretely in more than three directions in total, or changed continuously, or changed in a combination of discretely and continuously during the gradient pulse sequence, 0≦t≦echo time, where t represents the time. The method may be performed during a single shot (single MR excitation).

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 1^st 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.