Re: Error in computing CBF from perfusion image

[Ze Wang]

Hi Michele,

    The mean perfusion difference map seems ok to me. The extreme large value after CBF calculation may caused by one or two time points where the control images had large motions. I'm assuming that your data had no separate M0 image and you were using the control image as the M0.  The outlier cleaning scripts can remove the outliers.  Also, the image mask created before CBF calculation seems to be too stringent as a lot of voxels were excluded.  You can reduce the threshold in line 21 in batch_create_mask to get a larger mask. 0.15 should be fine.  If you have used fsl bet to create a brain mask for the asl images, you can use the mask in batch_perf_subtract.m too.

------ Original Message ------

From: "Michele Mauri" <maurimi...@gmail.com>

To: "Ze Wang" <red...@gmail.com>

Sent: 3/15/2021 11:34:54 AM

Subject: Error in computing CBF from perfusion image

Dear Dr. Wang,

I hope not to disturb you. If possible, I would like to ask you another question on the results that I get from ASLtbx.

I'm processing some single delay PCASL images but it seems that the computed CBF is way too high near the left skull. I attach here the mean perfusion image (which seems OK) and the mean CBF for your convenience.

Do you have any idea why this might happen? I tried to set all the parameters correctly and do the preprocessing in the right way.

Many thanks,

Michele Mauri

Fondazione Cà Granda IRCCS Ospedale Maggiore Policlinico

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