Slice scan time correction

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FMR Data Preprocessing

Slice scan time correction

As part of the data preprocessing, the slice scan time correction (which as of BVQX version 1.6 is done as the first step in a multi-step preprocessing) will correct for the differences in each slice's acquisition time. Currently, the following slice acquisition sequences / schemes are supported by the algorithm:

./.	stacked	interleaved 1	interleaved 2
ascending	Slice order: 1, 2, 3, ..., 24, 25	Slice order: 1, 3, ..., 25, 2, 4, ..., 24	Slice order: 2, 4, ..., 24, 1, 3, ..., 25
descending	Slice order: 25, 24, 23, ..., 2, 1	Slice order: 25, 23, ..., 1, 24, 22, ..., 2	Slice order: 24, 22, ..., 2, 25, 23, ..., 1

The term Slice order refers to the temporal sorting, so that, in time, for <ascending + interleaved 1> first, slice number 1 (the bottom-most slice) then slice numbers 3, 5, 7 and so forth are measured. The scan numbers displayed below the slices in the figures above thus relate to their temporal position, so that below the second slice you can see that it is measured as the 14th slice in the sequence.

Other, custom slice ordering sequences are not yet supported by BrainVoyager (as in other packages), but according to our experiences, these types of slice scanning sequences only have very little to no relevance in research practice.

As for the global options, there only remains the interpolation method, for which Sinc interpolation is the default (and linear interpolation should only be used in rare cases).

Please make sure that both the TR and the inter slice time (both configurable in the FMR project settings) are correct before performing this step!