Provided is a stable isotope-labeled aliphatic amino acid enabling the assignment of the signal of an amino acid residue side chain by increasing to the maximum the observation sensitivity to an NMR signal of the same amino acid residue side chain, and allowing NOE (nuclear Overhauser effect) between protons in the amino acid residue to be observed. The stable isotope-labeled aliphatic amino acid is for constituting a protein and satisfies all of the following conditions (1) to (3): (1) two or more carbon atoms are labeled with .sup.13C; (2) of two or more carbon atoms labeled with .sup.13C, a carbon atom other than a carbon atom of a methyl group, which is capable of bonding to a hydrogen atom, has one .sup.1H directly bonded thereto, while the carbon atom of the methyl group has at least one .sup.1H directly bonded thereto; and (3) other carbon atoms adjacent to all the .sup.13C are all .sup.12C.

The invention provides for a metal detector (100, 300) with at least a first coil (102) for generating a first magnetic field (108) along a first direction (119). The first coil is a split coil with a first (104) and a second (106) portion (104). A coil power supply (110) separately supplying time varying electrical power to the coil portions. At least one electrical sensor (116, 118) measures electrical data (136) descriptive of the electrical power supplied to at least the first coil portion and the second coil portion. The coils are controlled such as to move a field-free region in a predetermined pattern within a measurement zone. If metal is detected, the pattern is modified for refining localisation of the metallic object.

Systems and methods employing spin editing techniques to improve magnetic resonance spectroscopy (MRS) and magnetic resonance spectroscopic imaging (MRSI) are discussed. Using these spin editing techniques, magnetic resonance signals of one or more non-target chemicals (chemicals whose signals are to be filtered out or suppressed) chemicals can be suppressed, so that the signal(s) of a set of target chemicals can be obtained without signals from the one or more non-target chemicals. Information about and differences between the molecular topologies of the first set of chemicals and the one or more unwanted chemicals can be used to design a sequence that suppresses the one or more unwanted chemicals while allowing acquisition of signal(s) from the first set of chemicals. These techniques can be employed to recover sharp peaks despite magnetic field inhomogeneities and susceptibility effects.

A method to detect transient binding of a substrate molecule of interest in solution to a molecular target includes selecting the substrate molecule of interest and the molecular target such that the substrate molecule of interest can transiently bind to the molecular target; placing one of a sample or a subject of interest in a magnetic resonance (MR) apparatus, the sample or the subject of interest containing the substrate molecule of interest so as to be in contact with the molecular target; providing magnetic labelling of non-exchangeable or slowly exchangeable MR sensitive nuclei of the substrate molecule of interest; receiving an MR signal from the MR sensitive nuclei of the solvent molecules using the MR apparatus; and analyzing the MR signal to obtain a quantity associated with the transient binding of the substrate molecule of interest to the molecular target.

Methods of fingerprinting a specific molecule in a composition using nuclear magnetic resonance (NMR) is disclosed. The disclosed NMR methods provide several modifications and improvements over existing NMR techniques. In some embodiments, the methods include applying a cycle of signal processing steps, including applying a radio frequency (RF) pulse, applying a gradient pulse having a pulse length less than or equal to 1000 μs, and applying a water suppression technique (WET). In some embodiments, the methods further include repeating the cycle for at least 3 times to acquire an enhanced signal of the composition. In some embodiments, the methods further include fingerprinting the specific molecule based on the enhanced signal of the composition

Systems and methods are disclosed for a pulse sequence that reduces disorder and/or interaction effects in spin systems. A protocol can be used to design a pulse sequence that includes altering the frame orientation of the spin system with each electromagnetic pulse in the pulse sequence. The frame orientations during the sequence can conform to certain conditions. The number positive rotations along each axis can be the same as the number negative rotations along the respective axis. The number of rotations along one axis should be the same as the number of rotations along the other axes.

The invention features methods for detecting the hydration state or vascular volume of a subject using a device capable of nuclear magnetic resonance (NMR) measurement. The methods involve exposing a portion of a tissue of the subject in vivo to a magnetic field and RF pulse from the device to excite hydrogen nuclei of water within the tissue portion, and measuring a relaxation parameter of the hydrogen nuclei in the tissue portion, the relaxation parameter being a quantitative measure of the hydration state or vascular volume of the subject as a whole. The invention also features devices and computer-readable storage media for performing the methods of the invention.

A method and a device for performing homonuclear J-coupling spectroscopy on a sample, the method including: a) producing transverse magnetization in the sample by applying an RF excitation pulse at a nuclear magnetic resonance (NMR) frequency; b) after a delay τ, applying a refocusing pulse to the sample; c) performing a step of, applying another refocusing pulse to the sample after a delay 2τ, N times, where N ranges from N.sub.min to N.sub.max; d) following a final one of the refocusing pulses, acquiring an NMR signal from the sample; and repeating steps a)-c) for different values of N, adjusting τ so that a total time T=2(N+1)τ remains constant, where T is a time between a start of the RF excitation pulse and a center or a start of a final one of the NMR signals.

A method for generating a nuclear magnetic resonance spectrum of nuclear spin moments of a sample includes a static magnetic field permeating the sample, and a detection spin moment with a detection region surrounding the latter. The detection region extends at least partly into the sample. The method also includes an antenna element for radiating in frequency pulses for influencing the nuclear spin moments and radio-frequency pulses for influencing the detection spin moment, where a polarization step involves polarizing at least one portion of the nuclear spin moments along the magnetic field to form a longitudinal magnetization, where a transfer step involves converting the longitudinal magnetization (M.sub.x) into a transverse magnetization (M.sub.xy) by radiating in a frequency pulse (F) with a 90° flip angle, wherein a detection step involves radiating in a sequence of radio-frequency pulses onto the detection spin moment and subsequently detecting a signal (32′) of the transverse magnetization (M.sub.xy) present in the detection region and storing the signal as detection result in a list. The detection step is carried out a number of times repeatedly in succession, wherein the polarization step and the transfer step and also the detection steps are carried out.

The present invention discloses a method for selectively detecting dopamine based on magnetic resonance nuclear spin singlet state. The method uses the nuclear spin singlet of three hydrogen atoms on the dopamine benzene ring to achieve selective detection of dopamine signals in a complicated system. The present invention is based on magnetic resonance technology to detect dopamine, has good accuracy, sensitivity and selectivity, can accurately detect the signal of dopamine from the complicated system, and the interference of signals of other substances are well eliminated. Meanwhile, the present invention further has the advantages of simple operation and non-intervention, can be used for monitoring the content and distribution of the dopamine in a living body, and has important application value in the fields of biology and medicine.