Presented at the Neonatal Society 2010 Autumn Meeting.

Harris P¹, Ball G¹, Roze E¹, Merchant N^1,2, Arichi T^1,2, Porter E², Allsop JM¹, Edwards AD^1,2, Rutherford M¹, Counsell SJ¹

¹ Imaging Sciences Department, Imperial College and MRC Clinical Sciences Centre, Hammersmith Hospital, London, UK
² Division of Neonatology, Imperial College Healthcare Trust, London, UK

Background: Population based atlases, representing magnetic resonance imaging (MRI) data from a group of subjects aligned to a common imaging space are widely available in adult neuroimaging, providing normative data which allow the interpretation of new images. Diffusion tractography atlases provide information on the location of white matter tracts and are used to assess lesion location and the extent of tissue injury in, for example, adult stroke patients. Diffusion tractography is increasingly being used to assess brain development and injury in infants but no such atlases exist for the newborn brain. The aim of this study was to generate a probabilistic tractography atlas of the healthy infant brain at term which will be made widely available for use in future imaging studies.

Methods: Approval for MRI of infants was granted by the local Research Ethics Committee. We studied 15 healthy term control infants (8 male), with median (range) gestational age at birth of 40+3 weeks (38+1 to 41+5) and median age at imaging of 41+1 (38+2 to 43+5) weeks. Probabilistic tractography was performed using fsl (www.fmrib.ox.ac.uk). The fractional anisotropy (FA) maps of the 15 infants were co-registered to create a mean FA map, and the tracts were projected onto the mean FA map to produce a probabilistic tractography atlas. In an examplar study the tractographic data from an infant with a left middle cerebral artery (MCA) infarction was registered to the atlas.

Results: The atlas was successfully created and quantitative data on the size and microstructure of the tracts derived (Table 1). The examplar study showed that the corticospinal tracts were significantly smaller on the side of the lesion (Figure 1).

Conclusion: This 3 dimensional atlas of major white matter fibres in the healthy term brain allows non-subjective assessment the impact of a lesion on white matter development. The atlas will be made available on the internet (www.brain-development.org) for use by other neonatal research groups

Corresponding author: serena.counsell@imperial.ac.uk