Post-mortem assessment of rat spinal cord injury and white matter sparing using inversion recovery-supported proton density magnetic resonance imaging

Abstract

This was an experimental study. White matter sparing influences locomotor recovery after traumatic spinal cord injury (SCI). The objective of the present post-mortem magnetic resonance imaging (MRI) investigation was to assess the potential of a simple inversion recovery (IR) sequence in combination with high-resolution proton density (PD) images to selectively depict spared white matter after experimental SCI in the rat. This study was conducted at University of Liège and Centre Hospitalier Universitaire, Liège, Belgium and Hasselt University, Diepenbeek, Belgium. Post-mortem 9.4 tesla (T) MRI was obtained from five excised rat spines 2 months after compressive SCI. The locomotor recovery had been followed weekly using the standardized Basso-Beattie-Bresnahan scale. IR MRI was used to depict normal white matter as very hypo-intense. Preserved white matter, cord atrophy and lesion volume were assessed, and histology was used to confirm MRI data. MRI showed lesion severity and white matter sparing in accordance with the degree of locomotor recovery. IR MRI enhanced detection of spared and injured white matter by selectively altering the signal of spared white matter. Even subtle white matter changes could be detected, increasing diagnostic accuracy as compared to PD alone. MRI accuracy was confirmed by histology. High-resolution IR-supported PD MRI provides useful micro-anatomical information about white matter damage and sparing in the post-mortem assessment of chronic rat SCI.