Tractography-based quantitation of diffusion tensor imaging parameters in white matter tracts of preterm newborns.

PURPOSE To evaluate the feasibility of performing diffusion tensor tractography (DTT) to map and quantify the pyramidal white matter tracts of premature newborns. MATERIALS AND METHODS Fourteen diffusion tensor MRI (DTI) examinations of nine premature newborns were evaluated. DTT was performed to segment bilateral pyramidal tracts, using a fiber-tracking algorithm originating in the cerebral peduncle (CP) and filtering through the posterior limb of the internal capsule (PLIC) and precentral gyrus (PCG). Voxels containing the resulting tracts were then used for quantitation of DTI parameters along the tract. The DTT-based tract measurements were compared with standard manually placed region-of-interest (ROI) measurements at four locations along the pyramidal tract, and the reproducibility of each technique was evaluated. RESULTS DTT demonstrated improved reproducibility over manual ROI measurement for pyramidal tract quantitation and was less subject to intra-operator variability (P < 0.0001, Fisher test for equal variance). In general, the anatomic locations and measurements obtained with the two techniques were in good agreement, although some systematic differences were identified in the PLIC and CP. CONCLUSION Fiber DTT is feasible in premature newborns, provides more reproducible tract measurements than manual ROI methods, and allows quantitation along the entire tract for more detailed DTI assessment of white matter maturation.