Hi,
I’ve been creating a .json file for a 3T PRESS basis set and some spin systems and my basis set looks like it has a first order phase across it. I have used the object start times and durations from my sequence object to get my delays so I don’t think they’re wrong? Has anyone else experienced this and know what I’m probably doing wrong, and if it will then cause an issue later down the line in fitting?
Thank you,
Daniel
Hi @daniel , This looks like FSL. I think this will arise because if you take the exact timings from the scanner, typically the ADC event will be switched on before the echo time. This is done to mitigate ADC instability int he first few points. You have to adjust the timings of the simulated sequence (just the last delay) to fix this first-order phase.
You can do this by inspecting the pulse timings and working out when the ADC should start in simulation. And/or you can do this by empirically adjusting the time and looking at the phase of the peaks. You can see how I make my self a fine test set of spin systems in this example.
