Rapid three-dimensional gradient shimming method for reducing phase encoding number on nuclear magnetic resonance spectrometer

Abstract

The invention discloses a rapid three-dimensional gradient shimming method for reducing phase encoding number on a nuclear magnetic resonance spectrometer, which relates to a nuclear magnetic resonance spectrometer. A method of shimming coils is selected according to the phase encoding number, X and Y high-order shimming coils are deducted, on this basis, a proper revised regularization method can be added to the calculation, a good shimming effect can still be achieved when the phase encoding number can be reduced to be 3*3 or 2*2. These few 2*2 and 3*3 phase codes are widely applied to all three-dimensional gradient shimming pulse sequences of the nuclear magnetic resonance spectrometer, such as a three-dimensional gradient echo pulse sequence, a tilt three-dimensional gradient echo pulse sequence, and a pulse gradient field excitation echo pulse sequence. The mutual interference of multiple spectral peaks with farer chemical shifts can be overcome in the phase measurement. The three-dimensional gradient shimming in which the hydrogen nuclear is selectively excited enable the shimming method to get rid of the dependence on deuterium reagent, brings speed increase in cooperation with few phase encoding number and small-angle excitation, and has wide application range.

Description

technical field [0001] The invention relates to a nuclear magnetic resonance spectrometer, in particular to a fast three-dimensional gradient shimming method for reducing the number of phase codes on the nuclear magnetic resonance spectrometer. Background technique [0002] In the measurement of nuclear magnetic resonance, it is necessary to have a highly uniform magnetic field to obtain the fine splitting spectrum of nuclear magnetic resonance. NMR spectrometers are often equipped with a large number of shim coils. On NMR spectrometers, shim coils are generally named after the order of X, Y, and Z. Z1, Z2, Z3, Z4, Z5, Z6, and Z7 are the names of shim coils in the Z direction, from the 1st order to the 7th order of Z. X1, Y1, XZ, YZ, XY, XZ2, YZ2, ZXY, Z3X, Z3Y, Z2XY, Z4X, Z4Y, X2Y2, ZX2Y2, Z2X2Y2, X3, Y3, ZX3, ZY3 are a series of non-Z direction shim coils name. The shim coils whose X or Y order is greater than or equal to 2 are called high-order shim coils in the X and...

AI Technical Summary

Problems solved by technology

Therefore, the popularization and application of the previous three-dimensional gradient shimming method is easily restricted by the signal-to-noise ratio

In particular, the deuterated chloroform sample commonly used in NMR experiments has a deuteron concentration of only 1 / 9 of that of heavy water, which makes the three-dimensional gradient shimming of deuterons with a low signal-to-noise ratio face more serious application restrictions.

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