Abstract: 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).

Abstract: An imaging method (150, 190) for imaging a subject (16) including fibrous or anisotropic structures (102) includes acquiring a three-dimensional apparent diffusion tensor map (162) of a region with some anisotropic structures (102). The apparent diffusion tensor at a voxel is processed (164) to obtain eigenvectors (e1, e2, e3) and eigenvalues (&lgr;1, &lgr;2, &lgr;3). A three-dimensional fiber representation (208) is extracted (198, 200) using the eigenvectors and eigenvalues. During the extracting (198, 200), voxels are locally interpolated (202) in at least a selected dimension in a vicinity of the fiber representation (208). The interpolating includes weighting the voxels by a parameter indicative of a local anisotropy. The interpolating results in a three-dimensional fiber representation (208) having a higher tracking accuracy and representation resolution than the acquired tensor map (162).

Abstract: An imaging sequence, which generates a static image data set and a plurality of differently diffusion-weighted data sets, is repeated and the data sets stored in memories (360, 361, . . . , 36N). Each data set is reconstructed into corresponding images stored in sub memories (380, 381, . . . , 38N). The images are compared macroscopically (40) and shifted (42) into optimal alignment. Local regions of the images are analyzed (44) and adjusted (46) for better conformity. The static images and like spatially encoded images are compared with each other and those outside a preselected similarity threshold are rejected (48). The remaining like images are combined (50) and subject to a diffusion analysis (52) to generate an image of an anisotropic structure in the imaging region. The anisotropic structure and other image information are displayed on a monitor (58).

Abstract: An imaging sequence, which generates a static image data set and a plurality of differently diffusion-weighted data sets, is repeated and the data sets stored in memories (360, 361, . . . , 36N). Each data set is reconstructed into corresponding images stored in sub memories (380, 381, . . . , 38N). The images are compared macroscopically (40) and shifted (42) into optimal alignment. Local regions of the images are analyzed (44) and adjusted (46) for better conformity. The static images and like spatially encoded images are compared with each other and those outside a preselected similarity threshold are rejected (48). The remaining like images are combined (50) and subject to a diffusion analysis (52) to generate an image of an anisotropic structure in the imaging region. The anisotropic structure and other image information are displayed on a monitor (58).

Abstract: 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).

Abstract: An imaging method (150, 190) for imaging a subject (16) including fibrous or anisotropic structures (102) includes acquiring a three-dimensional apparent diffusion tensor map (162) of a region with some anisotropic structures (102). The apparent diffusion tensor at a voxel is processed (164) to obtain eigenvectors (e1, e2, e3) and eigenvalues (&lgr;1, &lgr;2, &lgr;3). A three-dimensional fiber representation (208) is extracted (198, 200) using the eigenvectors and eigenvalues. During the extracting (198, 200), voxels are locally interpolated (202) in at least a selected dimension in a vicinity of the fiber representation (208). The interpolating includes weighting the voxels by a parameter indicative of a local anisotropy. The interpolating results in a three-dimensional fiber representation (208) having a higher tracking accuracy and representation resolution than the acquired tensor map (162).

Abstract: An imaging method for imaging a subject (16) including anisotropic or fibrous structures (102) includes acquiring a three-dimensional apparent diffusion tensor map (44, 162) of a region with some anisotropic structures (102). The apparent diffusion tensor map (44, 162) is processed to obtain ordered eigenvectors and eigenvalues (48, 166) of diffusion tensor map voxels. A three-dimensional fiber representation (54, 208) is tracked using the eigenvectors and eigenvalues (48, 166). The three-dimensional fiber representation (54, 208) is rendered as a hyperstreamline representation (238). An background image representation (328) is generated. A human-viewable display (344) is produced including the rendered hyperstreamline representation (238) superimposed on the generated image background representation (328).

Abstract: The invention relates to a method of deriving time-averaged moments of a convolution profile from dynamic input and arrival profiles. A convolutive relation exists between the arrival profile and the input profile. According to the invention the time-averaged moment of the convolution profile is calculated from time-averaged moments of the dynamic input and arrival profiles. The method is used notably for the study of perfusion effects by means of magnetic resonance imaging.

Abstract: The invention relates to a magnetic resonance imaging method. The method includes the execution of image pulse sequences for the measurement of magnetic resonance image signals and navigator signals. After the execution of the image pulse sequence, the navigator MR signal is checked so as to determine whether the navigator MR signal meets a predetermined quality criterion. If the navigator MR signal does not meet the quality criterion, the navigator MR signal and the magnetic resonance imaging signals corresponding to the navigator MR signal are measured again.

Abstract: According to the known method, a reference measurement is performed by measurement of magnetic resonance signals, without application of a magnetic gradient field to introduce phase encoding in the magnetic resonance signals. According to the invention, two measurements are performed with a read-out gradient of opposite polarity at substantially corresponding instants, relative to an instant at which the contributions to the phase error due to frequency deviations are zero. The advantage of the novel method resides in the fact that a higher insensitivity to field inhomogeneities and chemical shifts is achieved.

Abstract: A diffusion weighted MR method for forming images of diffusion of spins in biological tissue. In order to correct macroscopic motions, the MR method measures navigator MR signals wherefrom a phase correction is derived for the MR signals. During the imaging of, for example a part of the brain of a human or animal, artefacts may arise at the areas of the image which correspond to regions in the part of the brain which contain CSF. The artefacts in the MR image can be reduced by determining a corrected phase, for measuring points having a modulus smaller than the threshold value, from the phases of different reference measuring points of the navigator MR signal for which the phase can be determined with a sufficiently small error.

Abstract: The invention relates to a fast imaging method based on gradient recalled echoes of nuclear spins whose excitation and echo formation are not contained in the same sequence. The method has an increased susceptibility to variations in the time constant T.sub.2.sup.* of the free induction decay of the MR signal and is used in, for example, functional MR imaging studies that are based on temporary changes in T.sub.2.sup.* which are caused by local changes in magnetic susceptibility e.g. local changes in brain oxygenation state of a human or animal body. In order to reduce the susceptibility of the image quality to motion navigator gradients are generated in each sequence so as to measure a navigator MR signal. From the measured navigator signals a phase correction is determined and the MR signals measured are corrected by means of this phase correction.