Activation of the sensorimotor cortex at 1.O T: Comparison of echo-planar and gradient-echo imaging

PURPOSE: The increasing demand for the clinical application of functional MR imaging raises the question of whether this technique can be routinely performed on 1.0-T MR scanners. To this end, we assessed the feasibility of functional MR imaging at 1.0 T, METHODS: Healthy volunteers were scanned during the performance of a motor task. Functional data were acquired with echo-planar imaging (EPI) and with gradient-echo (GRF) and dual-echo GRE sequences. The signal intensity variations of the EPI and GRE sequences were compared, and the influence of inflow and blood oxygen level-dependent (BOLD) effects on the signal variations was assessed with the dual-echo GRF sequences. RESULTS: In 11 of the 12 subjects we found activation in the primary motor cortex with both the GRE and EPI sequences. Active voxels had a significantly higher mean percentage of signal changes with the EPI sequence than with the GRE sequence (EPI: 1% to 6.1%, mean 2.4%; GRE: 1% to 4.5%, mean 1.9%), The EPI sequence was less sensitive to motion artifacts and enabled imaging of a larger brain volume in a shorter time. With a dual-echo sequence we found an increasing contribution of inflow effect with an increasing percentage of signal changes, CONCLUSION: Functional MR imaging of the sensorimotor cortex can be routinely performed at 1.0 T.