Abstract: A phantom calibration body (12) for calibrating diffusion MRI device (16) that mimics a material such as a mammalian tissue is disclosed. The phantom calibration body (12) includes a homogeneous aqueous solution (30) that contains a mixture of low molecular-weight and high molecular-weight polymers housed in a container (14) that is placed in the diffusion MRI device (16) for obtaining one or more diffusion MRI images of the phantom calibration body (12). A measure of diffusivity is calculated for each of the one or more diffusion MRI images in order to calibrate the diffusion MRI device. Methods of using the phantom calibration body (12) to calibrate diffusion MRI device (16) are also disclosed.

Abstract: Treatment apparatus includes a plurality of coils configured to generate time-varying magnetic fields that induce electric fields within a subject. In one example, electric field strengths of at least 1 V/cm are produced in brain tissues exhibiting Glioblastoma Multiforme (GBM). Fields are applied based on computer-assisted modeling using electromagnetic characteristics of the brain, and tissue locations identified as exhibiting disease using imaging data. A head mounted assembly of coils can be used for convenient, portable treatment.

Abstract: Magnetic resonance methods comprise tractographically establishing a path along a structure in a specimen and finding a distribution of structure radii or cross-sectional areas along the path. Based on the distribution and the path, end-to-end functional characteristics of the structure are estimated. For example, nerve transit times or distributions of transit times can be estimated for a plurality of nervous system locations such as Brodmann areas. Comparison of estimated transit times or distributions thereof between reference values or other values from the same structure can be used to assess specimen health.

Abstract: Using pulsed-field-gradient (PFG) sequences, the sizes of the pores in ordered porous media can be estimated from the “diffraction” pattern that the signal attenuation curves exhibit. A different diffraction pattern is observed when the experiment is extended to a larger number (N) of diffusion gradient pulse pairs. Differences in the characteristics of attenuation curves also permit distinguishing different pore shapes and distributions using the N-PFG technique. Using an even number of PFG pairs, an approximation to the average pore size can be obtained even when the sample contains pores with a broad distribution of sizes. Multi-PFG sequences can also be used to differentiate free and multi-compartment diffusion, and to estimate compartment sizes and orientations, and to distinguish microscopic and ensemble anisotropy.

Abstract: Magnetic resonance methods include modeling magnetic resonance signals obtained from specimens at low and high q-values to obtain parameters and distributions of parameters associated with specimen structure and orientation. In evaluation of brain white matter specimens, diffusion within axons can be modeled based on hindered diffusion parallel to an axis of the axon and restricted diffusion perpendicular to the axis. Diffusion exterior to axons can be modeled as hindered diffusion with differing diffusivities parallel to and perpendicular to the axis. Based on extracted parameters and associated model functions, distributions of specimen properties such as intra and extra-axonal principal diffusivities and the corresponding principal directions can be estimated. Features of the axon diameter distribution can also be estimated using this approach.

Abstract: A phantom calibration body (12) for calibrating diffusion MRI device (16) that mimics a material such as a mammalian tissue is disclosed. The phantom calibration body (12) includes a homogeneous aqueous solution (30) that contains a mixture of low molecular-weight and high molecular-weight polymers housed in a container (14) that is placed in the diffusion MRI device (16) for obtaining one or more diffusion MRI images of the phantom calibration body (12). A measure of diffusivity is calculated for each of the one or more diffusion MRI images in order to calibrate the diffusion MRI device. Methods of using the phantom calibration body (12) to calibrate diffusion MRI device (16) are also disclosed.

Abstract: An average propagator is estimated from diffusion-weighted magnetic resonance data. Diffusion-weighted signal attenuation data is determined from the diffusion-weighted magnetic resonance data. Estimated average propagator data is determined from the diffusion-weighted signal attenuation data based on at least one of a priori information of the diffusion-weighted signal attenuation data or a priori information of the average propagator.

Abstract: Using pulsed-field-gradient (PFG) sequences, the sizes of the pores in ordered porous media can be estimated from the “diffraction” pattern that the signal attenuation curves exhibit. A different diffraction pattern is observed when the experiment is extended to a larger number (N) of diffusion gradient pulse pairs. Differences in the characteristics of attenuation curves also permit distinguishing different pore shapes and distributions using the N-PFG technique. Using an even number of PFG pairs, an approximation to the average pore size can be obtained even when the sample contains pores with a broad distribution of sizes. Multi-PFG sequences can also be used to differentiate free and multi-compartment diffusion, and to estimate compartment sizes and orientations, and to distinguish microscopic and ensemble anisotropy.

Abstract: Magnetic resonance methods include modeling magnetic resonance signals obtained from specimens at low and high q-values to obtain parameters associated with specimen structure and orientation. In evaluation of brain white matter specimens, diffusion within axons can be modeled based on hindered diffusion parallel to an axis of the axon and restricted diffusion perpendicular to the axis. Diffusion exterior to axons can be modeled as hindered diffusion with differing diffusivities parallel to and perpendicular to the axis. Based on extracted parameters and associated model functions, specimen properties such as intra and extra-axonal principal diffusivities and the corresponding principal directions can be estimated.

Abstract: Magnetic resonance methods include modeling magnetic resonance signals obtained from specimens at low and high q-values to obtain parameters and distributions of parameters associated with specimen structure and orientation. In evaluation of brain white matter specimens, diffusion within axons can be modeled based on hindered diffusion parallel to an axis of the axon and restricted diffusion perpendicular to the axis. Diffusion exterior to axons can be modeled as hindered diffusion with differing diffusivities parallel to and perpendicular to the axis. Based on extracted parameters and associated model functions, distributions of specimen properties such as intra and extra-axonal principal diffusivities and the corresponding principal directions can be estimated. Features of the axon diameter distribution can also be estimated using this approach.

Abstract: Diffusion tensor magnetic resonance signals are analyzed. Diffusion weighted, signals are acquired, each signal having a plurality of voxels (10). The diffusion weighted signals are sampled to obtain at least one set of resampled diffusion weighted signals (11). A diffusion tensor for each voxel is determined from each set of the resampled diffusion weighted signals (12). An empirical statistical distribution is determined for a quantity associated with the diffusion tensor from the diffusion tensors determined from the at least one set of the resampled diffusion weighted signals (13).

Abstract: A method for measuring the mechanical integrity of a collagen network in cartilage and of other extracellular matrices according to applying a known mechanical stress to the sample; measuring a quantity representing hydration of the sample; and providing the extracellular network recoil pressure according to the known applied mechanical stress and the independently determined proteoglycan osmotic pressure corresponding to the hydration. In accordance with an embodiment of the present invention, an in vitro mechanowsmotic titration method for determining the collagen network tension (i.e., recoil pressure) for a given collagen network hydration is used. In accordance with a further embodiment of the present invention, the method may be used for diagnosing and/or monitoring the progression of diseases, such as osteoarthritis, preferably according to the collagen network stiffness, which for example, is shown to be reduced in osteoardritic cartilage compared with normal cartilage.

Abstract: A method for quantitatively assessing diffusion anisotropy according to an invariant anisotropy index that accounts for orientational coherence of the measured principal directions between different localized regions of an object to counteract the bias and increased variance effects of noise inherent in the diffusion measurement. A diffusion weighted imaging sequence is performed on a two-dimensional slice of an object to provide raw diffusion weighted image signals, which are processed by conventional Fourier transform and magnitude reconstruction to provide diffusion weighted images, from which a diffusion tensor is estimated for each voxel of the imaged slice. In each voxel a lattice anisotropy index is calculated as a function of both the eigenvalues and eigenvectors of neighboring voxels such that intervoxel orientational coherence compensates noise-induced bias effects. The orientational coherence measure between two voxels is calculated according to an intervoxel deviatoric tensor dot product.

Abstract: A method and system for measuring the effective diffusion tensor for spin labeled particles, and generating images therefrom. The effective diffusion tensor is related to the echo intensity in an NMR spin-echo experiment. This relationship is used to design experiments from which the diffusion tensor components are estimated. Estimation of Deff provides the theoretical basis for a new MRI modality, diffusion tensor imaging. Diffusion ellipsoids may be used for generating images representative of physical characteristics of the observed object. Scalar invariants of the diffusion tensor are also used for imaging.

Abstract: A biological implantable pressure sensor element comprises a fixed volume pouch formed by a sealed, flexible, impermeable membrane comprising therewithin a gel mass contained in a gel volume, said gel being hydrated with an aqueous solution comprising an agent having at least a first and a second NMR-detectable form, the proportion of the first to the second form of the agent in the gel volume being determined by their electrolytic interaction with the gel, whereby when an external pressure is applied to the sensor element a d (chemical shift)/d(.sigma./K) greater than 0.0001 ppm is attained, wherein .sigma. is the external pressure and K is the modulus of the gel. A kit contains sterile, individually wrapped sensor elements.

Abstract: A biological inplantable pressure sensor element comprises a fixed volume pouch formed by a sealed, flexible, impermeable membrane comprising therewithin a gel mass contained in a gel volume, said gel being hydrated with an aqueous solution comprising an agent having at least a first and a second NMR-detectable form, the proportion of the first to the second form of the agent in the gel volume being determined by their electrolytic interaction with the gel, whereby when an external pressure is applied to the sensor element a d(chemical shift)/d(.sigma./K) greater than 0.0001 ppm is attained, wherein .sigma. is the external pressure and K is the modulus of the gel. A kit contains sterile, individually wrapped sensor elements.