Spinal cord functional MRI at 3 T: gradient echo echo-planar imaging versus turbo spin echo

The purpose of this study was to evaluate and compare turbo spin echo (TSE) with gradient echo echo-planar imaging (GE-EPI) pulse sequences for functional magnetic resonance imaging (fMRI) of spinal cord activation at 3 T field strength. Healthy volunteers underwent TSE and GE-EPI spinal fMRI. The activation paradigm comprised the temporal alternation of finger motion and rest. Pulse sequences were optimized to obtain sufficient image quality and optimal sensitivity to small T(2) or T(2)* relaxation time changes. Spinal cord activation measured by the two pulse sequences was evaluated with respect to spatial distribution of activation, signal sensitivity, and reproducibility. For the GE-EPI sequence, fMRI activation was maximal in the spinal cord segments at the levels of the fifth cervical down to the first thoracic vertebra. For the TSE sequence, fMRI measurements showed no distinct location with maximal activation. Percentage signal change and number of activated voxels were approximately twice as high for GE-EPI compared to TSE fMRI. Reproducibility of the signal changes was much better for GE-EPI than for TSE imaging. To conclude, multi-subjects averaged GE-EPI is more location specific for blood-oxygen-level-dependent (BOLD) activation, more sensitive, and is suggested to be more reproducible than TSE fMRI.