Prognostic value of gray matter to white matter ratio in hypoxic and non-hypoxic cardiac arrest with non-cardiac etiology

Purpose This study evaluated the prognostic performance of the gray to white matter ratio (GWR) on brain computed tomography (CT) in out-of-hospital cardiac arrest (OHCA) survivors with a noncardiac etiology and compared the prognostic performance of GWR between hypoxic and nonhypoxic etiologies. Methods Using a multicenter retrospective registry of adult OHCA patients treated with targeted temperature management, we identified those with a noncardiac etiology who underwent brain CT within 24 hours after restoration of spontaneous circulation. Attenuation of the gray matter and white matter (at the level of the basal ganglia, centrum semiovale, and high convexity) were measured and GWRs were calculated. The primary outcome was neurologic outcome. Results Of 164 patients, 145 (88.4%) were discharged with a poor neurologic outcome. Lower GWR was associated with a poor neurologic outcome. The sensitivities of this marker were markedly low (9.7%-43.5%) at cutoff values, with 100% sensitivity. The cutoff values of the GWR for hypoxic arrest showed higher sensitivities than those for nonhypoxic arrest. The area under the curve (AUC) values of the GWR for the caudate nucleus/posterior limb of the internal capsule, putamen/corpus callosum, and basal ganglia were significant in the hypoxic group, whereas the AUC of the putamen/corpus callosum was the only significant GWR in the nonhypoxic group. Conclusion A low GWR is associated with poor neurologic outcome in noncardiac etiology OHCA patients treated with targeted temperature management. Gray to white matter ratio can help to predict the neurologic outcome in a cardiac arrest with hypoxic etiology rather than a nonhypoxic etiology.