Figure 1.
Flowchart: Assembling a Baby Brain Structural Network.
After a set of diffusion-weighted images is acquired (1), a quality assurance step is performed in which data affected by motion are rejected and the remaining images are corrected for eddy current distortions and affine head motion (2). Although this step may not be necessary in cooperative adults, it is essential for high-quality tractography in infants. The diffusion tensor is calculated for the resulting data (3), and whole-brain streamline fiber tractography is undertaken (4). The subcortical surface is extracted (5) and partitioned into nodes using either the gridded or equipartition parcellation scheme (6, see below). Node-track and node-node connections are derived (7) and the adjacency matrix is constructed (8).
Figure 2.
Parcellation Schemes and Adjacency Matrices.
a) Equipartition and b) gridded parcellation of the six-month old baby brain. c), d) Adjacency matrices binarized with threshold 1 for both parcellation schemes in a representative baby with NMS 0, for which no diffusion directions were discarded.
Figure 3.
Correlations between Neuromotor Score and Small World Properties.
Observed correlations between neuromotor score and characteristic path length (a and b) and average clustering coefficient (c and d) in babies with encephalopathy.