Susceptibility-matched padding improves the quality of cervical and lumbar spinal fMRI

Abstract

Spinal cord functional magnetic resonance imaging (fMRI) has advanced significantly in recent years, revealing insights into the function of somatosensory and motor systems. However, the complex environment of the spinal cord induces unique sources of noise, limiting the quality of spinal fMRI recordings. Various hardware and software solutions have been proposed to address these challenges. Among them, susceptibility-matched padding has gained popularity due its low cost, ease of use, and effectiveness in reducing static B0 field inhomogeneities, which are a major source of artefacts in spinal fMRI. Despite anecdotal evidence, the impact of susceptibility-matched padding on the quality of spinal cord fMRI has not been assessed systematically. We investigated the effects of non-protonated perfluorocarbon liquid-filled padding (SatPad) on B0 field homogeneity and functional echo-planar imaging (EPI) in cervical and lumbar spinal cord in 10 healthy volunteers. Participants underwent two resting-state fMRI scanning sessions, one per cord section. Within each session they were scanned with and without SatPad in a pseudo-randomised order. The use of SatPad increased B0 field homogeneity and improved functional image quality metrics, including temporal signal-to-noise ratio, timeseries coefficient of variation, DVARS, and ghosting artefacts. While both cervical and lumbar cord data benefited from the use of SatPad, greater effects were observed in the cervical cord. These findings provide a compelling basis for integrating susceptibility-matched padding into routine spinal fMRI protocols.