METHOD AND DEVICE FOR INSPECTION BY MEANS OF NUCLEAR MAGNETIC RESONANCE

摘要

PURPOSE:To obtain a tomographic image with good resolving power in a short time by changing forcibly the direction of magnetization by the system of at least 3 kinds of pulses (90 deg. pulse, 180 deg. pulse, 90 deg. pulse) and returning the magnetization to a thermal equil. state in a short time. CONSTITUTION:Electric current is conducted to a coil 1 for static magnetic field to apply a static magnetic field H0 in a specimen (the specimen is placed in the cylinder of each coil). Electric current is conducted to a coil 3 for z-gradient magnetic field by a control circuit 4 to apply a z-gradient magnetic field Gz<+> thereto. A gate circuit 61 is opened under the application of the Gz<+> and an excitation coil 5 is excited by a 90 deg. pulse from an oscillator 6. x-, y-Gradient magnetic fields GX, GY are similarly applied in succession and an NMR resonance signal is detected from a detection coil 7. A 180 deg.-X pulse is applied to the coil 5 through the circuit 61 and an NMR resonance signal (echo signal) is similarly detected. A 90 deg. pulse is again applied to the coil 5 at the point of the time when the echo signal is max. to return the magnetization to a thermal equil. state.