Predicting outcome with diffusion-weighted imaging in cardiac arrest patients receiving hypothermia therapy: Multicenter retrospective cohort study

Objectives: Many comatose patients following cardiac arrest have ischemic brain injury. Diffusion-weighted imaging is a sensitive tool to identify hypoxic-ischemic brain injury. The accurate prediction of the prognosis for comatose cardiac arrest survivors has been challenging, and thus, a multimodal approach, combining diffusion-weighted image findings, could be feasible. The aim of this study was to assess regional brain injury on diffusionweighted imaging and to test the potential association with its neurologic outcome in patients treated with target temperature management after out-of-hospital cardiac arrest. Design and Setting: A multicenter, registry-based, retrospective cohort study was conducted using cases from 24 hospitals across South Korea. Of the 930 adult (≥18 yr) nontraumatic outof-hospital cardiac arrest patients treated with target temperature management between January 2007 and December 2012 at these hospitals, we included the patients who underwent brain diffusion-weighted imaging in the first week after cardiac arrest. The brain regions examined included the four cerebral lobes, basal ganglia-thalamus, brain stem, and cerebellum. Imaging results were compared between a good neurologic outcome, defined as a cerebral performance category score of 1 or 2, and a poor neurologic outcome (cerebral performance category score. 3). Measurement and Main Results: Poor neurologic outcome occurred in 118 of the 172 patients analyzed (68.6%). Positive diffusion-weighted image findings, defined as any regional brain injury lesion in diffusion-weighted imaging, were present in 106 patients. Positive diffusion-weighted image findings had 93% sensitivity, 86% specificity, 76% positive predictive value, and 96% negative predictive value for a poor neurologic outcome. The poor outcome group had higher numbers of affected brain lesions than the good outcome group (3.8 ± 1.9 vs 0.1 ± 0.6; p < 0.01). By multivariate analysis, positive diffusion-weighted image findings (odds ratio, 58.2; 95% CI, 13.29.254.91) and lack of a shockable rhythm (odds ratio, 0.13; 95% CI, 0.03.0.57) were associated with a poor neurologic outcome. Conclusions: Diffusion-weighted imaging allows reliable prediction of poor neurologic outcome in comatose patients treated with target temperature management after out-of-hospital cardiac arrest. Further prospective validation study will be required to generalize this result.