Magnetic resonance tomography and localised spectroscopy - has gp. of impulse sequences, contrast chemicals and data analysis to improve resolution

摘要

In a nuclear magnetic resonance system, the signal acquisition period is chosen in relation to the spin locking period of the magnetising. This allows the formation or influence of picture contrast or characteristic resonance by :- (a) one of the two variables of the rotating coordinates of the spin lattice relaxation time; (b) the frequency dependance of one of these two variables. (c) The susceptability dependance of one of these two variables. Pref the spin locking is at or near resonance where the effective magnetic field is aligned with the magnetising to be locked or, off resonance to reduce power demand for the high frequency RF field but allow missalignment of the effective field from the field to be locked. USE/ADVANTAGE - In nuclear magnetic resonance based tomography, localised relaxometry and localised spectroscopy. Previously inaccessible material characteristics can be identified. When contrast intensifiers are used the doses can be considerably reduced. Information can be taken as contrast or volume selection data measurements. No additional measurements are necessary in normal areas.