Three‐dimensional spiral technique for high‐resolution functional MRI

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Abstract
For high‐resolution functional MRI (fMRI) studies, signal‐to‐noise ratio (SNR) plays an important role. Any method that results in an improvement in SNR will be able to improve the quality of activation maps. Three‐dimensional (3D) acquisition methods in general can provide higher SNR than that of 2D methods due to volume excitation. To demonstrate the superiority of 3D methods for high‐resolution fMRI scans, a comparison study between 3D and 2D spiral methods was performed using a contrast‐reversing checkerboard visual stimulus. A 3‐inch surface coil was used to limit the in‐plane FOV to 14 cm × 14 cm so that 32 1‐mm slices with an in‐plane voxel size of 1.1 mm × 1.1 mm could be acquired within 5.76 seconds. Results showed that average numbers of activated voxels were 407 and 841 for 2D and 3D methods, respectively (P < 0.01). Therefore, the 3D technique may be a useful alternative to the conventional 2D method for high resolution fMRI studies. Magn Reson Med 58:947–951, 2007.