Comparison of a 32-channel with a 12-channel head coil: are there relevant improvements for functional imaging?

ABSTRACT

PURPOSE: To evaluate the suitability of a 12- or 32-channel head coil and of a prescan normalization filter for functional magnetic resonance imaging (fMRI) studies at different brain regions. MATERIALS AND METHODS: fMRI was obtained from 36 volunteers executing a visually instructed motor paradigm using a 12-channel head matrix coil and a 32-channel phased-array head coil with and without prescan normalization filtering at 3 T. The time-course signal-to-noise ratio (tSNR) and the magnitude of functional activation (beta-value, t-value, percent signal change) were statistically compared between experimental conditions for the contralateral primary motor and visual cortex, contralateral thalamus, and ipsilateral anterior cerebellar hemispheres. RESULTS: tSNR was higher overall measuring with the 32-channel array and with prescan normalization. Without filtering, the 32-channel array delivered higher functional activation magnitudes for the visual cortex, whereas the 12-channel array seemed superior in this respect in thalamus and cerebellum. Filtering did not considerably affect the fMRI-activation magnitude detected from the 12-channel coil; its application favored the 32-channel coil at the subcortical and cerebellar locations but disfavored it at the cortical ones. CONCLUSION: The 32-channel coil detected more fMRI-activation cortically but less subcortically than the 12-channel coil; prescan normalization improved activation parameters only at central brain structures.