Rabbit Encephalopathy of Prematurity MRI Data

Ex vivo MRI was performed on fixed brains as described. Newborns rabbits were perfused using the active staining technique to introduce the gadolinium-based MRI contrast agent (Magnevist®, Dimeglumine Gadopentetate 0.5 mmol/mL, Bayer Schering Pharma, Berlin, Germany) into the brain parenchyma. After perfusion fixation with 4% PFA in 0.1 mol/L phosphate buffer (pH 7.4) containing 2% (10 mM) gadoteridol, the heads were removed and immersed in PFA 4% for 48h. Finally, the fixed brains, still in the cranium, were placed in PBS containing 1% (5 mM) gadoteridol at 4°C for 2 to 5 days to ensure equilibration of contrast agent, and tissue rehydration. The heads were trimmed and placed in a sample holder, surrounded by proton-free perfluoropolyether solution (Fomblin®, Solvay Solexis) that minimizes susceptibility artefacts at the interface and imaging was done with a Bruker Biospec 9.4 Tesla small animal MR scanner (Bruker Biospin, Ettlingen, Germany; horizontal bore, 20 cm) equipped with actively shielded gradients (600 mT/m) and a 3.5 cm quadrature coil (volume resonator, Rapid Biomedical, Rimpar, Germany). Analysis was done with automated template propagation for the neonatal rabbit brain and subsequent T1 volumetric data and DTI derived fractional anisotropy (FA) and mean diffusivity (MD) were calculated. The volumes of each brain region were analyzed as absolute values and relative values after normalization to the body weight or total brain volume from the same animal. Data from the left and right hemispheres were summed together.