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How do we decide truncation points? If a TE of 20 ms is used on 1.5 T, 25 truncation points give good results, however if the same TE is used on 7T the 25 truncation points give more resultant residue and distorted resultant estimate and original.
Kindly provide with the rationale behind this and truncation points to be used for rat brain MRS data at 7T.For background handling, QUEST exploits the fact that macromolecule and lipid signals decay rapidly in the time-domain, so the major part of the background signal is in the very first points of the signal. Strategic truncation of these initial samples can separate the metabolite part from any fast decaying parts and thus decorrelate metabolite and nuisance parameters.
How to choose the number of the pseudo-truncated points?
The lipid (if not too huge) and macromolecule signals must have decayed into the noise by sample point Ntrunc. This number depends on the magnetic field strength and the sampling interval. For rat brain MRS data at 7T, I use data 20 points but it is probably not the best value for you case.
Danielle Graveron-Demilly
Danielle Graveron
Universite Claude Bernard - LYON 1
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