Higher Sensitivity and Reproducibility of Wavelet-Based Amplitude of Resting-State fMRI

Fei-Fei Luo; Jian-Bao Wang; Li-Xia Yuan; Zhi-Wei Zhou; Hui Xu; Shao-Hui Ma; Yu-Feng Zang; Ming Zhang

doi:10.3389/fnins.2020.00224

Higher Sensitivity and Reproducibility of Wavelet-Based Amplitude of Resting-State fMRI

Front Neurosci. 2020 Mar 31:14:224. doi: 10.3389/fnins.2020.00224. eCollection 2020.

Authors

Fei-Fei Luo^{1

2}, Jian-Bao Wang^{3

4

5}, Li-Xia Yuan^{3

4

5}, Zhi-Wei Zhou^{3

4

5}, Hui Xu², Shao-Hui Ma², Yu-Feng Zang^{3

4

5}, Ming Zhang²

Affiliations

¹ The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Institute of Biomedical Engineering, School of Life Sciences and Technology, Xi'an Jiaotong University, Xi'an, China.
² Department of Medical Imaging, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China.
³ Institutes of Psychological Sciences, Hangzhou Normal University, Hangzhou, China.
⁴ Zhejiang Key Laboratory for Research in Assessment of Cognitive Impairments, Hangzhou, China.
⁵ Center for Cognition and Brain Disorders, The Affiliated Hospital, Hangzhou Normal University, Hangzhou, China.

Abstract

The fast Fourier transform (FFT) is a widely used algorithm used to depict the amplitude of low-frequency fluctuation (ALFF) of resting-state functional magnetic resonance imaging (RS-fMRI). Wavelet transform (WT) is more effective in representing the complex waveform due to its adaptivity to non-stationary or local features of data and many varieties of wavelet functions with different shapes being available. However, there is a paucity of RS-fMRI studies that systematically compare between the results of FFT versus WT. The present study employed five cohorts of datasets and compared the sensitivity and reproducibility of FFT-ALFF with those of Wavelet-ALFF based on five mother wavelets (namely, db2, bior4.4, morl, meyr, and sym3). In addition to the conventional frequency band of 0.0117-0.0781 Hz, a comparison was performed in sub-bands, namely, Slow-6 (0-0.0117 Hz), Slow-5 (0.0117-0.0273 Hz), Slow-4 (0.0273-0.0742 Hz), Slow-3 (0.0742-0.1992 Hz), and Slow-2 (0.1992-0.25 Hz). The results indicated that the Wavelet-ALFF of all five mother wavelets was generally more sensitive and reproducible than FFT-ALFF in all frequency bands. Specifically, in the higher frequency band Slow-2 (0.1992-0.25 Hz), the mean sensitivity of db2-ALFF results was 1.54 times that of FFT-ALFF, and the reproducibility of db2-ALFF results was 2.95 times that of FFT-ALFF. The findings suggest that wavelet-ALFF can replace FFT-ALFF, especially in the higher frequency band. Future studies should test more mother wavelets on other RS-fMRI metrics and multiple datasets.

Keywords: amplitude of low-frequency fluctuation; reproducibility; resting-state fMRI; sensitivity; wavelet transform.