Normal canine brain maturation at magnetic resonance imaging

Area of Science:

• Veterinary Neurology
• Comparative Neuroimaging
• Developmental Neuroscience

Background:

• Neonatal canine brains differ significantly from adult brains, with developmental changes including decreasing water content and increasing myelination.
• These maturational processes are detectable using magnetic resonance imaging (MRI) and follow a predictable timeline.
• Understanding these changes is crucial for interpreting canine neuroimaging studies.

Purpose of the Study:

• To characterize the developmental changes in the normal neonatal canine brain using standard MRI sequences.
• To identify clinically relevant milestones in canine brain development and maturation.
• To compare canine brain development patterns with those observed in humans.

Main Methods:

• Seventeen healthy neonatal dogs were scanned using MRI at various ages from 1 to 36 weeks.
• Acquired MRI sequences included T1-weighted (T1W), T2-weighted (T2W), fluid attenuated inversion recovery (FLAIR), short tau inversion recovery (STIR), and diffusion-weighted imaging (DWI).
• Images were subjectively assessed for gray and white matter signal intensity, correlated with histologic findings.

Main Results:

• Canine brain development qualitatively mirrors human development, adequately characterized by T1W and T2W MRI sequences.
• Neonatal canine cortex shows reversed gray-to-white matter signal intensity compared to adults, with isointense transitions occurring at 3-4 weeks (T1W) and 4-8 weeks (T2W).
• A mature gray-to-white matter intensity pattern is largely achieved by 16 weeks; FLAIR sequences reveal an additional signal reversal in juveniles due to high subcortical white matter water content.

Conclusions:

• Standard MRI sequences, particularly T1W and T2W, effectively characterize neonatal canine brain development.
• Established MRI milestones provide a reliable reference for assessing canine brain maturation.
• The developmental trajectory of the canine brain on MRI shows similarities to that of humans.