In vivo imaging of the human brain at 1.5 T with 0.6-mm isotropic resolution

We present high-resolution in vivo anatomical scans with 3D whole-brain coverage and an isotropic resolution of 0.6 mm, obtained at a clinical field of 1.5 T. The data are acquired in 10 independent scans over two sessions using a 3D magnetization-prepared, gradient echo sequence, modified to output phase images in addition to magnitude images. The independent scans are coregistered to correct for head motion, prior to performing complex averaging. The resolution of the final, averaged image, is found to be equal to the nominal one. The separation between the distribution of gray-scale values characterizing the gray and white matter, respectively, is substantially improved over single-scan images. Complex and magnitude averaging are compared and found to deliver similar results for regions with a high initial signal-to-noise ratio (SNR) within the brain. However, complex averaging is strongly recommended for quantitative applications or for studies where regions of low initial SNR are important. To summarize, a method for high-resolution in vivo anatomical imaging at a clinical field strength is demonstrated and is recommended for brain mapping. The method can also be applied at higher fields with a reduced acquisition time.