Dear SPM experts,
I use an EPI sequence with a TR = 1s and a MB-factor = 6 and I have issues with determinung which model I have to use for the autocorrelation.
Corbin et al. (2018; Accurate modelling of temporal correlations in rapidly sampled fMRI time series using “FAST”.) recommended the FAST algorithm for TR < 1.5s, which was found to perform better in modelling autocorrelation in general (Olszowy et al., 2019; Accurate autocorrelation modeling substantially improves fMRI reliability).
However, in paper investigating the effect of different MB-factors (e.g. Bhandari et al., 2020; Multiband acceleration can provide moderate improvements in single-subject voxel-wise statistics in block-design task-based fMRI; Sahib et al., 2016; Effect of Temporal Resolution and Serial Autocorrelations in Event-Related Functional MRI) it seems like the TR for analysis gets divided by the MB-factor, which I don't really understand, as the interscan interval for modelling is the TR. But, if it is the case that the TR gets divided by MB, the effective TR would be 0.16s, for which the recommondation of Corbin et al. does not apply for as they just investigated a range of TR > 0.35s and Bhandari et al. and Sahib et al. even found the FAST algorithm to be over conserative in a case like that.
I feel like I misunderstood something. Does anybody has an idea or a recommondation?
Thank you very much in advance!
Kind regards,
Falko
--
Falko Mecklenbrauck, M.Sc.
PhD Student
University of Münster
Institute of Psychology
Biological Psychology
Fliednerstr. 21
Room 310b
Tel.: +49 251 83 34101
|