USA As Represented by Secretary of the Navy

David G Cory

Joel B Miller

Allen N Garroway

A method for obtaining a nuclear magnetic resonance image of a sample is performed by first placing the sample in a homogeneous static magnetic field excited with a homogeneous transmitter device. Spin magnetization in the sample is thus initially detected with an inhomogeneous receiver device such that an induced voltage in the receiver device depends on a spatial location of precessing nuclei in the sample. Then, a spatial coupling of the sample and the receiver device is varied and the spin magnetization in the sample is again detected with the inhomogeneous receiver device. The full spatial distribution of the spin density of the sample and hence an image of the sample is then determined with the spin magnetizations detected. Either the sample is moved relative to the receiver device, or the spatial coupling of the receiver device and the sample is electronically altered. Any spin interactions are eliminated by using coherent averaging techniques before the detecting steps. In addition, during the varying step, the spin magnetization is either: left in the transverse plane; stored along the static magnetic field direction; allowed to equilibrate along the static magnetic field direction; or spin locked.

NMR imaging with varying spatial coupling

An improved method and apparatus for nuclear magnetic resonance (NMR) imaging are provided by intercalating a magnetic field gradient in the form of short pulses into an NMR line-narrowing sequence. By inserting the short pulses into predetermined windows in the line-narrowing pulse sequence, the resolution of NMR images obtained thereby is increased and image artifacts from homogenous contributions to the natural linewidth are reduced. Furthermore, the short gradient pulses may be intercalated into known multiple pulse sequences or new multiple pulse sequences for specific imaging purposes which allows far more freedom in designing efficient and improved pulse cycles for NMR imaging.

Nuclear magnetic resonance imaging with short gradient pulses

A method is provided for measuring the distribution of the extent of molear transport along two orthogonal directions, and further for measuring the anisotropy of molecular transport. For a sample which consists of compartments which contain mobile spins, such as round or cylindrical micelles, the distribution of compartment eccentricities can be calculated from this measurement. This method enables the anisotropy of molecular transport to be determined for a sample independently of any bulk orientation within the sample and thus the anisotropy of local geometries can be determined.

Growing community of inventors

Billerica, MA, United States of America

David G Cory