Hitachi, Ltd.

Hitachi Medical Corporation

Yukari Onodera

Etsuji Yamamoto

Hiroyuki Itagaki

Yo Taniguchi

Ryuichi Suzuki

Hiroyuki Takeuchi

Hisaaki Ochi

An inspection method by means of an inspection apparatus using nuclear magnetic resonance and having magnetic field generating apparatus for generating a static magnetic field, gradient magnetic fields and an RF magnetic field; magnetic field generating apparatus by means of additional shim coils, which vary homogeneity of the static magnetic field by varying current flowing therethrough; signal detecting apparatus for detecting nuclear magnetic resonance signals from an object to be inspected; an apparatus for processing signals detected by the signal detecting apparatus; and control apparatus for controlling currents flowing through the shim coils, which method using nuclear magnetic resonance comprises a step of storing shim currents corresponding to each of a plurality of slices, capable of improving homogeneity of the static magnetic field for each of the plurality of slices, and a step of switching over the shim currents to those corresponding to a relevant slice to be measured prior to measurements of nuclear magnetic resonance signals from the slice. This inspection method can be applied also to a case where measurements of other slices are effected in intervals of measurements of the relevant slice.

Inspection method and apparatus using nuclear magnetic resonance

An inspection apparatus using magnetic resonance includes magnetic field generators for generating a static magnetic field, a gradient magnetic field and a radio frequency magnetic field, respectively, a signal detector for detecting magnetic resonance signals from an inspected object, a computer for executing arithmetic operations for detection signals from the signal detector and an output device of the result of the arithmetic operations by the computer. The gradient magnetic field generator includes first and second gradient coils, the first gradient coil is a coil fixed to a magnet for generating a static magnetic field, the second gradient coil is a movable coil, and the magnetic field generated by the second gradient coil at a conducting portion of the magnet is offset by the magnetic field generated by the first gradient coil. According to this construction, an eddy current that occurs with the time change of the gradient magnetic field can be reduced.

Inspection apparatus using magnetic resonance

In an inspection apparatus using nuclear magnetic resonance (NMR), a spatial distribution of homogeneity of a static magnetic field can be quickly measured even when a heterogeneous object is inspected, by measuring simultaneously phase data and a transverse relaxation time at the same spatial position of the heterogeneous object, removing the difference of a phase term due to a chemical shift by anticipating components at that position and obtaining only the phase data resulting from static magnetic field inhomogeneity. A plurality of low-pass filters are provided to a shim power supply unit for driving a shim coil for generating additional static magnetic fields to correct static magnetic field homogeneity so that a low-pass filter having a small time constant is used at the time of adjustment of static magnetic field homogeneity so as quickly adjust static magnetic field homogeneity, and a low-pass filter having a large time constant is used at the time of the actual measurement of the object in order to prevent degradation of S/N of signals.

Inspection method and apparatus using nuclear magnetic resonance (NMR)

NMR signals of low concentration solutes are obtained with suppression of NMR signal of solvent by sequentially applying a first RF pulse sequence, a 180.degree. RF pulse and a second RF pulse sequence to an object. Each of the first and second RF pulse sequence includes equally spaced RF pulses which have flip angles in accordance with binominal coefficients. Phase errors due to inhomogeneity of a static magnetic field are cancelled through the two-time application of equally spaced RF pulse sequence.

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Asaka, Japan

Yukari Onodera