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Two‐point T 1 measurement: Wide‐coverage optimizations by stochastic simulations
Author(s) -
Lin Max S.,
Fletcher James W.,
Donati Robert M.
Publication year - 1986
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910030405
Subject(s) - algorithm , computer science , ideal (ethics) , point (geometry) , context (archaeology) , inversion (geology) , mathematics , geometry , structural basin , biology , paleontology , philosophy , epistemology
Stochastic reliability of T 1 measurement from image signal ratios is examined in the ideal case by stochastic simulations in the context of wide‐coverage optimizations. Precise measurements prove to be accurate, and accurate ones precise. Sign‐preserved inversion‐recovery (IR)/non‐IR techniques are the best ration method, reciprocal non‐IR/IR ones being equivalent, but inconvenient. Wide‐coverage optima are relatively unsharp. Suggested guidelines for covering the 150‐ to 1500‐ms T 1 band are minimal relevant T E ; T 1 about 400 ms; effective repetition times about in the ratio, T R2 (IR)/ T R1 (non‐IR) = 2.5–3.0, and in a sum as long as possible up to about T R1 + T R2 = 3.5–4.0 s; signal‐averaging after and only after T R1 + T R2 has been lengthened to the said region. Also suggested are different guidelines for covering T 1 bands, 120–1200 and 200–1800 ms. Typically, precisions and accuracies improve linearly or faster with increasing S / N and ( S / N ) 2 , respectively. Unnecessarily high pixel resolutions or thin slicings exact great penalties in accuracies. Progressively shortening T R1 eventually transforms a wide coverage into a sharp targeting with small potential gains in a narrow T 1 locality and large compromises almost everywhere else. The simulations yield an insight into applicabilities of standard error propagation analyses in two‐point T 1 measurement. © 1986 Academic Press, Inc.