Dear All,
Hi
There is a parameter in tarquin called water attenuation which needs to be changed according to a formula in manual for different TEs and field strengths.
My data is MRSI,TE=144,3 T
I chose 250 for metabolite T2 according to this paper:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3852663/...just a rough estimate…and I got this number:0.2940(water t2:80)
But stronger field caused shorter T2 and longer TE, both means more signal loss
So why did I get smaller number?
I hope I understand the question correctly; are you wondering why the “water attenuation” factor (defined here (an older link)) gets smaller as TE increases? Note that this factor is the ratio of the T2 decay of the water signal, over that of the metabolites; it accounts for the differences in T2 relaxation between the metabolite and water signals.
It is correct that the longer TE generally leads to more signal loss – but, the water signal has a shorter T2 (faster decay) than the metabolites – so when you’re scaling to that water signal the adjustment factor gets smaller.