An empirical investigation of the benefit of increasing the temporal resolution of task-evoked fMRI data with multi-band imaging

Virág Darányi,István Homolya,Petra Hermann,Zoltán Vidnyánszky,Zoltan Nagy

doi:10.1007/s10334-021-00918-z

Abstract

ObjectiveThere is a tendency for reducing TR in MRI experiments with multi-band imaging. We empirically investigate its benefit for the group-level statistical outcome in task-evoked fMRI.MethodsThree visual fMRI data sets were collected from 17 healthy adult participants. Multi-band acquisition helped vary the TR (2000/1000/410 ms, respectively). Because these data sets capture different temporal aspects of the haemodynamic response (HRF), we tested several HRF models. We computed a composite descriptive statistic, H, from β’s of each first-level model fit and carried it to the group-level analysis. The number of activated voxels and the t value of the group-level analysis as well as a goodness-of-fit measure were used as surrogate markers of data quality for comparison.ResultsIncreasing the temporal sampling rate did not provide a universal improvement in the group-level statistical outcome. Rather, both the voxel-wise and ROI-averaged group-level results varied widely with anatomical location, choice of HRF and the setting of the TR. Correspondingly, the goodness-of-fit of HRFs became worse with increasing the sampling frequency.ConclusionRather than universally increasing the temporal sampling rate in cognitive fMRI experiments, these results advocate the performance of a pilot study for the specific ROIs of interest to identify the appropriate temporal sampling rate for the acquisition and the correspondingly suitable HRF for the analysis of the data.

Highlights

After the development of in-plane parallel imaging methods in the 1990’s, [1,2,3] slice-wise acceleration, a.k.a. simultaneous multi-slice (SMS) or multi-band (MB) imaging, was proposed by Larkman et al in the early 2000’s [4] and subsequently refined by others to become a widely utilized neuroimaging method [5,6,7].A reasonable supposition is that increasing the temporal sampling rate (i.e. shorter repetition time (TR)) should improve the detection of blood-oxygen-level-dependent (BOLD) signal
To assess whether the increased temporal sampling rate provides an overall benefit, the grouplevel t values were further averaged across hemodynamic response functions (HRFs) for an easier comparison of MB factors
In regions of interest (ROIs) analysis the main effect of the HRF model and the interaction of MB factor and HRF model were statistically significant at p < 0.0001 for each of the four ROIs (Table 3)

Summary

Introduction

After the development of in-plane parallel imaging methods in the 1990’s, [1,2,3] slice-wise acceleration, a.k.a. simultaneous multi-slice (SMS) or multi-band (MB) imaging, was proposed by Larkman et al in the early 2000’s [4] and subsequently refined by others to become a widely utilized neuroimaging method [5,6,7].A reasonable supposition is that increasing the temporal sampling rate (i.e. shorter repetition time (TR)) should improve the detection of blood-oxygen-level-dependent (BOLD) signal (see for example Feinberg et al [8]). The benefit of higher number of data points per unit time is in resting-state functional magnetic resonance imaging (fMRI), MB imaging has shown utility [8, 9]. It is still unclear when the benefits of the higher temporal sampling outweigh the correspondingly incurred SNR loss in task-based fMRI efforts [10,11,12]. Due to the shorter TR, temporal autocorrelations may increase in the voxel-wise time course of fMRI data, which require careful additional processing before reliable statistical inference can be drawn [15, 16]

Methods

Results

Discussion

Conclusion