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Optimal time spacings for T 2 measurements: monoexponential and biexponential systems
Author(s) -
Shrager R. I.,
Weiss G. H.,
Spencer R. G. S.
Publication year - 1998
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/(sici)1099-1492(199810)11:6<297::aid-nbm531>3.0.co;2-a
Subject(s) - nuclear magnetic resonance , chemistry , physics
We have developed an optimal design strategy, i.e. a choice of times at which the magnetization should be measured, in spin‐echo measurements, when the number of measurements is fixed in advance. Results are given for samples whose relaxation is described by either an exponential or biexponential decay curve. The analysis is based on having an initial estimate of the ranges in which the relaxation times are likely to lie. The optimal design consists of a set of easily parameterized non‐uniformly spaced measurement times, as opposed to present implementation of spin‐echo experiments. Analysis of the biexponential case shows that an order of magnitude greater signal‐to‐noise is required to achieve T 2 estimates of comparable precision to monoexponential measurements with the same number of data points. The optimal designs lead to an improved ability to discriminate between two relatively similar relaxation times. © 1998 John Wiley & Sons, Ltd.