Are all fMRI sequences equal? An investigation into functional reproducibility in EPI and zero TE sequences for animal fMRI

Motivation: fMRI typically uses EPI; however, EPI is problematic, particularly for animal studies. Zero TE sequences offer a motion-insensitive, acoustically silent alternative to EPI. Goal(s): This study acquired and analyzed age-matched mice, scanned at 9.4T for fMRI using EPI, ZTE and SORDINO, to test the reliability and reproducibility of functional connectivity produced by each sequence. Approach: Interhemispheric differences, significance and test/retest metrics across scans were calculated for 10 key networks at a group level. Results: When compared to conventional EPI FC, zero TE sequences demonstrate similar network correlations and levels of reproducibility across scans. Thus, zero TE sequences are a feasible alternative to EPI. Impact: Validating an alternative to EPI fMRI offers researchers greater breadth in the design of their experiments; the motion insensitivity, acoustic silence and lack of susceptibility artifacts allows for more complex imaging systems, such as multi-modal setups and stimulation paradigms.