Preparing HCP-aging data for aslprep: multiple PostLabelingDelay values

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according to this https://groups.google.com/a/humanconnectome.org/g/hcp-users/c/2li3DdK5asc , it seems that the HCP-aging PCASL volume is acquired with multiple PostLabelingDelay values

Is it even possible to include multiple values in the *_asl.json? like for instance:

“PostLabelingDelay”: [0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.2, 0.7, 0.7, 0.7, 0.7, 0.7, 0.7, 0.7, 0.7, 0.7, 0.7, 0.7, 0.7, 1.2, 1.2, 1.2, 1.2, 1.2, 1.2, 1.2, 1.2, 1.2, 1.2, 1.2, 1.2, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 1.7, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2, 2.2]

additionally, given that the 4D PCASL volume also included 2 ‘noise’ volumes at the end. Should the *_aslcontext.tsv look something like this:

volume_type
control
label
control
label
.
.
.
m0
m0
noise
noise
2

Yes, this is supported in BIDS.

ASLPrep supports multi-PLD data, and it should ignore the noise volumes, though they need to be called “noRF”, not “noise”. That said, I believe the HCP ASL pipeline includes some steps that are not supported in ASLPrep. I can’t remember exactly what they were, but @tientong might recall since she looked into it a while ago.

3

Ashley Ptinis has an example BIDS curation for HCP-aging here: bids-examples/2d_mb_pcasl at master · bids-standard/bids-examples · GitHub

As @tsalo mentioned, running ASLPrep on HCP-aging isn’t sufficient to correct for the banding artifact in this data. This paper described the ASL sequence and HCP ASL processing pipeline.

4

thanks, the BIDS example is very helpful. Though the order of the m0scan and noRF volumes *asl.nii.gz and *aslcontext.tsv in the BIDS example is not the same as HCP aging

this is the order in the BIDS example

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.
.
label
control
noRF
noRF
m0scan
m0scan

this is the order in the actual HCP aging *asl.nii.gz and *aslcontext.tsv

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label
control
m0scan
m0scan
noRF
noRF