A magnetic resonance imaging (MRI) apparatus for obtaining a magnetic resonance (MR) image, based on a multi-echo sequence, and a method of the MRI apparatus are provided. The MRI apparatus includes a data obtainer configured to obtain first echo data, based on an echo that is generated at a first echo time, and obtain second echo data, based on an echo that is generated at a second echo time later than the first echo time, the first echo data including a part overlapping a part included in the second echo data in a k-space. The MRI apparatus further includes an image processor configured to reconstruct the MR image, based on the first echo data and the second echo data.

In an MRI scanner, the transmission and reception of RF excitation and detected signal waves is accomplished using far field excitation instead of conventional near field excitation. By superimposing two counter-propagating waves from the same source in the MRI sample interference fringes are recorded in the sample in such a way that the relative phase between the two propagation wave vectors determines the periodicity of the maxima and minima in the interference fringe pattern. The complete fringe pattern, known as a spatial hologram, contains both the phase and amplitude information of the information-bearing wave. When exposed to a replica of the original reference wave, the fringe pattern acts as a diffraction grating, reproducing the information-bearing field propagating at the same relative phase.

A method for evaluating drilling fluid includes making an NMR measurement of a sample of the drilling fluid and inverting the measurements to compute a corresponding T1T2 plot. The T1T2 plot is in turn evaluated to characterize the drilling fluid. In one embodiment, a stability index of the fluid may be computed from multiple NMR measurements made while aging the sample.

Technologies applicable to NMR spin-echo amplitude estimation are disclosed. Example methods may calibrate for distortion of a shape and estimated amplitude of measured NMR spin or gradient echoes. NMR spin or gradient echo measurements may be performed on a sample. The measured NMR spin or gradient echoes may be used to calculate an echo-shape calibration factor. The echo-shape calibration factor may estimate an effect of echo shape on estimated spin or gradient echo amplitude(s) of the NMR spin or gradient echoes. The echo-shape calibration factor may be used to correct for underestimation or overestimation of the spin or gradient echo amplitude(s).

An NMR method and apparatus for analyzing a sample of interest applies a static magnetic field together with RF pulses of oscillating magnetic field across a sample volume that encompasses the sample of interest. The RF pulses are defined by a pulse sequence that includes a plurality of measurement segments configured to characterize a plurality of relaxation parameters related to relaxation of nuclear magnetization of the sample of interest. Signals induced by the RF pulses are detected in order to derive the relaxation parameters. The measurement segments of the pulse sequence include at least one first-type measurement segment configured to characterize relaxation of spin-lattice interaction between nuclei of the sample of interest in a rotating frame (T.sub.1ρ) at a predefined frequency. The T.sub.1ρ parameter can be measured in conjunction with the measurement of other relaxation and/or diffusion parameters as part of multidimensional NMR experiments.

A method for homogenizing the static magnetic field with a distribution B0(r) in the active volume of a magnetic resonance apparatus having a number N of shim coils defines a target field distribution B0T(r) using a filter method in which a norm of the shim currents is influenced by means of filter factors. An optimization procedure works in a parameter space having M control parameters, wherein 2≤M<N. One of the control parameters is used as a weighting parameter for modification of a spatial weighting function and another control parameter is used to control the filter factors. Using this method the hardware limitations can be taken into account when determining the target field distribution, without a significant increase in the computational effort to determine the target field distribution during optimization.

A nuclear magnetic resonance (NMR) apparatus includes at least one magnet configured to induce a static magnetic field in a sample of material to be analyzed. At least one radio frequency antenna is configured to induce a radio frequency magnetic field in the sample of material to be analyzed. The sample chamber is disposed in a substantially longitudinally continuous sample holder separated into discrete sample chambers. Each sample chamber has an internal opening dimension such that substantially all of each sample is affected by surface contact phenomena with an internal wall of each sample chamber.

A system and method are provided for determining a spatial distribution of susceptibility in a subject using a magnetic resonance imaging (MRI) system. The method includes directing the MRI system to acquire imaging data from an imaging volume within a subject, wherein the imaging volume is subject to both background fields (B.sub.B) originating outside the imaging volume and local fields (B.sub.L) originating from tissue within the imaging volume. The method also includes selecting a size and non-central compute point for an extended Poisson kernel to be applied to the imaging data, subtracting from a delta function to control the background fields (B.sub.B) but not the local fields (B.sub.L), and producing a susceptibility report attributable to the local fields (B.sub.L).

The invention relates to a method for determining a parameter representative of the stability of an asphaltene-containing petroleum product, said petroleum product being an effluent derived from a hydrocarbon feedstock conversion process or being a mixture of hydrocarbons, using proton NMR to determine a threshold value of said parameter representative of the stability, this threshold value constituting a boundary between a stability domain and an instability domain of a petroleum product. According to the invention, the parameter representative of the stability is a T.sub.2mean/T.sub.1mean or T.sub.1mean/T.sub.2mean ratio. The invention also relates to a method for monitoring a conversion process, in particular a deep conversion process, or a mixture of hydrocarbons, using this method of determination.

According to some aspects, a laminate panel is provided. The laminate panel comprises at least one laminate layer including at least one non-conductive layer and at least one conductive layer patterned to form at least a portion of a B.sub.0 coil configured to contribute to a B.sub.0 field suitable for use in low-field magnetic resonance imaging (MRI).