3 Tesla is twice as sensitive as 1.5 Tesla magnetic resonance imaging in the assessment of diffuse axonal injury in traumatic brain injury patients

Diffuse axonal injury (DAI), associated with deafferentation and functional rearrangement, probably plays a role in the chronic phase of traumatic brain injury (TBI). DAI with a haemorrhagic component can be quantified using magnetic resonance imaging (MRI) thanks to the iron-based susceptibility effect of haemosiderin, which increases with magnetic field strength. The aim of this work was to compare conventional 1.5 Tesla and 3 Tesla MRI in the assessment of DAI in TBI patients. Eighteen TBI patients were submitted, in random order, to a 1.5T and a 3T MRI examination using standard gradient echo sequences. Both scans were always performed on the same day. DAI lesions with a haemorrhagic component were manually segmented and classified by anatomical location. The Wilcoxon and ANOVA tests were used for statistical analysis, significance being set at p<0.05. The results of this study showed that 3T MRI is almost twice as sensitive as 1.5T MRI in assessing DAI in terms of lesion number and volume. Differences between the two scanners were not significant in the posterior cranial fossa. High-field MRI enhances the assessment of DAI and may help to increase understanding of the mechanisms underlying subacute and chronic clinical, cognitive and behavioural changes in TBI patients.