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. 2017 Aug 14;5:159. doi: 10.3389/fped.2017.00159

Figure 1.

Figure 1

Structural magnetic resonance imaging (MRI) data preprocessing pipeline. Figure illustrates structural MRI data preprocessing pipeline, using a representative ex-33 week premature infant scanned at 4-weeks corrected age (2.75 months postnatal age). Panel (A) shows conversion of original T1-weighted image (T1file, in sagittal view) to a standardized brain orientation (T1file_std). Note, anterior (A) and posterior (P) are flipped in reoriented file. Panel (B) illustrates process of brain extraction. Manually edited binary mask (T1file_bet_mask; red) is shown superimposed on T1 image (grayscale), as well as finalized extracted brain (T1file_brain). Panel (C) illustrates the process of bias field correction. FMRIB’s Automated Segmentation Tool tissue-type segmentation (_seg) and estimated bias field (_bias) output files are shown. The latter image reflects gradient of tissue-specific signal inhomogeneity, showing hypo- (black) and hyper-intense (white) regions across entire T1 image. Hyperintense subcortical regions present in original T1 image are attenuated following intensity normalization, creating finalized structural Reference image (T1file_ref).