Structurally segregated and functionally specialized regions of the human cerebral cortex are interconnected by a dense network of cortico-cortical axonal pathways. By using diffusion spectrum imaging, we noninvasively mapped these pathways within and across cortical hemispheres in individual human participants. An analysis of the resulting large-scale structural brain networks reveals a structural core within posterior medial and parietal cerebral cortex, as well as several distinct temporal and frontal modules. Brain regions within the structural core share high degree, strength, and betweenness centrality, and they constitute connector hubs that link all major structural modules. The structural core contains brain regions that form the posterior components of the human default network. Looking both within and outside of core regions, we observed a substantial correspondence between structural connectivity and resting-state functional connectivity measured in the same participants. The spatial and topological centrality of the core within cortex suggests an important role in functional integration.

Simultaneous multi-slice EPI acquisition using parallel imaging can decrease the acquisition time for diffusion imaging and allow full-brain, high resolution fMRI acquisitions at a reduced TR. However, the unaliasing of simultaneously acquired, closely spaced slices can be difficult, leading to a high g-factor penalty. We introduce a method to create inter-slice image shifts in the phase encoding direction to increase the distance between aliasing pixels. The shift between the slices is induced using sign- and amplitude-modulated slice-select gradient blips simultaneous with the EPI phase encoding blips. This achieves the desired shifts but avoids an undesired “tilted voxel” blurring artifact associated with previous methods. We validate the method in 3× slice-accelerated spin-echo and gradient-echo EPI at 3T and 7T using 32-channel RF coil brain arrays. The Monte-Carlo simulated average g-factor penalty of the 3-fold slice accelerated acquisition with inter-slice shifts is <1% at 3T (compared to 32% without slice-shift). Combining 3× slice acceleration with 2× in-plane acceleration, the g-factor penalty becomes 19% at 3T and 10% at 7T (compared to 41% and 23% without slice-shift). We demonstrate the potential of the method for accelerating diffusion imaging by comparing the fiber orientation uncertainty, where the three-fold faster acquisition showed no noticeable degradation.