Slice timing calculation

[John_Kwon]

Hi, I’m working with an old BIDS dataset which doesn’t have json files for the NIfTI datas.
I want to calculate the slice timing using the provided scan protocols.

Provided datas are
Multi-slice mode: interleaved
Series: interleaved

If, for example, TR=2.0 and # of slices = 8,
Do I just put slicetiming = ( [2, 4, 6, 8, 1, 3, 5, 7] - 1 ) / 8 * 2.0 = [0.25, 0.75, 1.25, 1.75, 0.0, 0.5, 1.0, 1.5]
This is from what i read on neurostars.

Adding Correct Slice Timing Information Into JSON files

fMRIPrep accepts datasets that are in BIDS format. According to BIDS: Key name Requirement level Data type Description SliceTiming RECOMMENDED, but REQUIRED for sparse sequences that do not have the DelayTime field set, and Arterial Spin Labeling with MRAcquisitionType set on 2D. array of numbers The time at which each slice was acquired within each volume (frame) of the acquisition. Slice timing is not slice order – rather, it is a list of times containing the time (in seconds) of ea…

I understand that for siemens interleaved, the slice order is 2, 4, 6, 8, 1, 3, 5, 7. (And the numbers represent the anatomical order)
From what i understand, i figured that 2nd slice is measured at 0.0, then the 4th slice is measured at 0.25s, …, 8th slice is measured at 0.75s, then 1st slice at 1.0s, …, 7th slice at 1.75s.
So then shouldn’t slicetiming be [1.0, 0.0, 1.25, 0.25, 1.5, 0.5, 1.75, 0.75]?

Also, does Multi-slice mode: interleaved mean nothing in this case?

[effigies]

“Interleaved” is generally not enough information. There are five possible interleaved timings, which are summarized by the functions at in nipy.algorithms.slicetiming.timefuncs. What you’re describing is st_13024(), which is consistent with it being a Siemens machine with an even number of slices.