Calculated spin density, $T_1$ and $T_2$ images in NMR

Abstract

A study of spin density($\rho$) and relaxation time ($T_1$, $T_2$) distributions in NMR imaging is presented. Spin density and spin-lattice relaxation time calculations are performed using two repeated images which differ in repetition times while $T_2$ calculation is performed using the multiple spin-echo method. It is shown that the results obtained by the saturation recovery method with spin-echo(SRSE) is as good as the one obtained by the inversion recovery technique for the measurement of $T_1$ according to the criterion defined by the minimum error multiplied by the square root of imaging time. The optimal pulse timings for SRSE and multiple spin-echo are determined through the computer simulation based on the expected experimental conditions. The results obtained by computer simulations and experiments using the slice imaging with line-integral projection reconstruction are presented to demonstrate the advantages of SRSE. Similar results are expected for other imaging methods such as the total volume imaging with plane-integral projection reconstruction as well as 2-D and 3-D direct Fourier imaging.