Slice profile effects and their calibration and correction in quantitative NMR imaging

The signal values extracted from an NMR image matrix depend upon the NMR properties of the sample material, i.e. the proton density and relaxation times T1 and T2, and also upon various instrument parameters, one such being the slice shape. It is a common approximation to assume an ideal slice profile: one that is perfectly rectangular and invariant in shape for all applications, but in practice real slice profiles are neither. In this study the effect of the slice is included in signal intensity calculations by means of a computer simulation. Comparison is made between these slice-corrected values and values calculated on the basis of an ideal slice. Four pulse sequences are examined: saturation recovery, inversion recovery, spin echo and inversion recovery followed by spin echo.