Prognostic significance of magnetic resonance imaging in patients with severe nonpenetrating traumatic brain injury requiring decompressive craniectomy

Background Diffuse axonal injury (DAI) detected on magnetic resonance imaging (MRI) may be useful to predict outcome after traumatic brain injury (TBI). Methods This study compared the ability of the International Mission for Prognosis and Analysis of Clinical Trials (IMPACT) prognostic model with DAI on MRI, to predict 18-months neurological outcome in 56 patients who had required a decompressive craniectomy after TBI. Results Of the 56 patients included in the study (19 scans occurred within 14 days; median time for all patients 24 days, interquartile range 14-42), 18 (32%) had evidence of DAI on the MRI scans. The presence of DAI on the MRI diffusion-weighted (DW), T2*-weighted-gradient-echo and susceptibility-weighted (SWI) sequences was associated with an increased risk of unfavorable outcome at 18-months compared to those without DAI (44% vs. 17%, difference=27%, 95% confidence interval 2.4-46.7%; p=0.032), particularly when brainstem was involved. However, neither the grading (I to IV) nor the number of brain regions with DAI was as good as the IMPACT model in discriminating between patients with unfavorable and favorable outcome (area under the receiver-operating-characteristic curve: 0.625 and 0.621 vs 0.918, respectively; p