Hi all ! I have 100 patients with a pASL sequence and would like to get some information about the CBF. Is this actually possible with just one TI ? Can I somehow calculate an arterial transit time ? Because if I just measure at one time-point, I do not know whether the bolus has already passed or not arrived yet, right ? Is it only useful for grey matter or also white matter ?
Thanks for any help !
Dear Bernd, with single TI you can just calculate CBF. You will need a M0 image (acquired separately) or you can use a control image to calibrate your measurements (after correcting for TR). I would suggest to read the white paper published last year: You can find a link attached.
Regards!!
http://onlinelibrary.wiley.com/doi/10.1002/mrm.25197/abstract
Q: Is this actually possible with just one TI ?
A: Yes, if the labeling parameters including TI were set properly. Please check the white paper above.
Q: Can I somehow calculate an arterial transit time ?
A: You cannot measure ATT from your single TI data. However, BAT can be measured or estimated from multiple TIs ASL.
Q: I do not know whether the bolus has already passed or not arrived yet, right ?
A: If your TI - TI1 was chosen larger than BAT (assuming your ASL is QUIPSS2 ), or your labeling parameters were set properly, the bolus should have already passed. However, vascular disease patients might have specially long BAT.
Q: Is it only useful for grey matter or also white matter ?
A: Accurate WM CBF from ASL is in challenge. Your WM CBF might be biased for the several reasons. e.g. long ATT in WM, low ASL signal, partial GM volume effects...
White paper would answer your question more clearly.
Hope it helps!
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