title: Comparison of a 32-channel with a 12-channel head coil: are there relevant improvements for functional imaging?
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors: Functional Imaging Unit, Center of Diagnostic Radiology and Neuroradiology, University of Greifswald, Germany. evangelia.kaza@uni-greifswald.de
authors: Evangelia
authors: E
authors: Kaza
authors: Uwe
authors: U
authors: Klose
authors: Martin
authors: M
authors: Lotze