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bioRxiv · 10.1101/076307

A comprehensive evaluation of multiband-accelerated sequences and their effects on statistical outcome measures in fMRI.

Lysia Demetriou·Oliwia S Kowalczyk·Gabriella Tyson·Thomas Bello·Rexford D Newbould·Matthew B Wall
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Abstract

Accelerated functional Magnetic Resonance Imaging (fMRI) with multiband sequences is now relatively widespread. These sequences can be used to dramatically reduce the repetition time (TR) and produce a time-series sampled at a higher temporal resolution. We tested the effects of higher temporal resolutions for fMRI on statistical outcome measures in a comprehensive manner on two different MRI scanner platforms. Experiment 1 tested a range of acceleration factors (1-6) against a standard EPI sequence on a single composite task that maps a number of basic sensory, motor, and cognitive networks. Experiment 2 compared the standard sequence with acceleration factors of 2 and 3 on both resting-state and two task paradigms (an N-back task, and faces/places task), with a number of different analysis approaches. Results from experiment 1 showed modest but relatively inconsistent effects of the higher sampling rate on statistical outcome measures. Experiment 2 showed strong benefits of the multiband sequences on results derived from resting-state data, but more varied effects on results from the task paradigms. Notably, the multiband sequences were superior when Multi-Voxel Pattern Analysis was used to interrogate the faces/places data, but showed less benefit in conventional General Linear Model analyses of the same data. In general, ROI-derived measures of statistical effects benefitted relatively little from higher sampling resolution, with decrements even seen in one task (N-back). Across both experiments, results from the two scanner platforms were broadly comparable. The statistical benefits of high temporal resolution fMRI with multiband sequences may therefore depend on a number of factors, including the nature of the investigation (resting-state vs. task-based), the experimental design, the particular statistical outcome measure, and the type of analysis used. Higher sampling rates in fMRI are not a panacea, and it is recommended that researchers use multiband acquisition sequences conservatively.

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Lysia Demetriou, Oliwia S Kowalczyk, Gabriella Tyson, Thomas Bello, Rexford D Newbould, Matthew B Wall. 2016-09-20. A comprehensive evaluation of multiband-accelerated sequences and their effects on statistical outcome measures in fMRI.. https://doi.org/10.1101/076307

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