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Hi Mark, Thanks for the detailed reply, it was very helpful. cheers, wolf Mark Jenkinson wrote: > Hi, > > This program calculates signal loss as a dimensionless fraction such > that if you multiply > the image without loss by this image then you would get the equivalent > image with > signal loss. Hence the output is actually more like signal retained. > That is, a value of > 1 in the output means no signal loss, while a value of 0 means all the > signal was lost. > > The default value of TE is set to a ridiculous value so that you can't > run it sensibly > with the default, as you really must specify a correct TE value and > there is no > typical value that would work for any sizable number of people. > > This program is very simple in concept, and just works out the signal > loss factor > for the through slice dephasing, based on an ideal slice selection - > which is a sinc > function. Any number of papers/books will probably contain this, > although the > formula here is derived from scratch given that I do several slightly > tricky things > with estimating field-gradients separately in different sub-components > of the voxel. > > Hope this helps. > > All the best, > Mark > > > wolf zinke wrote: > >> Hi all, >> >> I came across the sigloss tool, which might do exactly what I want. >> So, instead of reinventing wheels I would like to understand this >> program a bit better. >> >> The output is in the range of 0 to 1 if I got everything right. What >> is the dimension and how do I interpret the values. >> There is the --te option. Do I understand it right that this results >> in an estimate of signal loss for a given TE? Why is it than set per >> default to 1s, which is far beyond normally used values? Is there any >> reference this program is based on? >> >> Thanks in advance for your help, >> wolf > >