Thank you Michael for your reply.

I have some updates and follow-up questions.

1. Apologies for the typing mistake, the bolus length for pASL is 1400 ms and not 1800 ms. I asked around and got to know that it is the maximum bolus length and not the definite or in other words 'fixed' bolus duration. So, I tried running the analysis with different bolus lengths, like 800 ms (as recommended in white paper), 900 ms, 1000 ms, 1100 ms and 1400 ms. 800 ms showed the most reasonable results, the arrival in GM and WM show the expected trend although the values still look small. Plus, the perfusion values appear fine too. Otherwise, when I increase the bolus length, the arrival times decrease further and there is a drastic decrease in GM perfusion as well. This is just a hit and trial method, is there a good way to find the optimal bolus length in this case?

Logfile
Using BASIL step /tmp/fsl_23ErzK_ox_asl/pvcorr/basil/step4
Mean perfusion in gm is 122.975541
Mean arrival in gm is 0.667703
Mean perfusion_wm in wm is 52.352250
Mean arrival_wm in wm is 0.839660
Mean perfusion_calib in gm is 49.266130
Mean perfusion_wm_calib in wm is 20.973217


2. Yes, the hadamard images are already decoded. I did the analysis again with updated --tis and --bolus of 350 ms, the results are quite reasonable now.

logfile
Using BASIL step /tmp/fsl_7tizDL_ox_asl/pvcorr/basil/step3
Mean perfusion in gm is 82.213683
Mean arrival in gm is 0.885986
Mean perfusion_wm in wm is 44.124690
Mean arrival_wm in wm is 1.231217
Mean perfusion_calib in gm is 40.885448
Mean perfusion_wm_calib in wm is 21.943522


3. I also have single PLD pcASL data of the same person, acquired in the same session (labeling duration 1800 ms, PLD 1800 ms).

Logfile
Using BASIL step /tmp/fsl_RSGx85_ox_asl/pvcorr/basil/step2
Mean perfusion in gm is 107.269536
Mean arrival in gm is 1.279414
Mean perfusion_wm in wm is 38.112337
Mean arrival_wm in wm is 1.613168
Mean perfusion_calib in gm is 46.785086
Mean perfusion_wm_calib in wm is 16.622510

4. The difference between the perfusion values from pcASL (single-PLD and Hadamard multi-PLD) is not that big, so I'm assuming that the Hadamard analysis is somewhat optimized now. But, if I compare the pASL and Hadamard arrival values and GM perfusion values, there is a difference. Is this much difference justified as the two techniques have different inversion efficiencies and have their own pros and cons?

Thanking in advance.
Amnah

########################################################################

To unsubscribe from the FSL list, click the following link:
https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=FSL&A=1