Improved determination of spin density T1 and T2 from a three-parameter fit to multiple-delay-multiple-echo (MDME) NMR images

A method is presented for simultaneously determining values of relative hydrogen spin density Nsub(r), T1 and T2 from a single set of NMR image intensities acquired in a short imaging time. Multiple-echo data are collected at multiple delays in virtually the same imaging time used to obtain T1 and a T2-weighted Nsub(r) from a separate saturation recovery (SR) T1 measurement. All three parameters are then determined by a three-parameter fit of a derived signal intensity equation to these multiple-delay-multiple-echo (MDME) data, providing an inherent correction of Nsub(r) for T1 and T2 weighting without the use of sequences with Tsub(D)>5T1, and without further data collection for a separate T2 measurement. It also provides an effective reduction in the noise of the separate T2 measurement. A three-parameter fit to MDME data appears to be superior to the separate T1 and T2 measurements currently used to determine all three parameters. Calculations performed on CrCl3 solutions produced T1 values from 21 ms to 3.4s, T2 values from 6 to 714 ms, and standard errors as low as 0.33%, with a net imaging time of the order of that required for routine low-noise signal intensity imaging. (author)