Timing of brain computed tomography for predicting neurological prognosis in comatose cardiac arrest survivors: a retrospective observational study

BACKGROUND: To assess the association between relevant brain computed tomography(CT) parameters at different time and neurological prognosis in adult comatose survivors after cardiac arrest(CA). METHODS: A total of 94 CA patients who underwent early and late CT scans(within 24 h and 24 h to 7 d respectively after CA) between January 2018 and April 2020 were enrolled in this retrospective study. According to the Cerebral Performance Category(CPC) score at hospital discharge, the patients were divided into either a good outcome(CPC 1–2) group or a poor-outcome group(CPC 3–5). The grey-to-white matter ratio(GWR) and the proportion of cerebrospinal fluid volume(pCSFV) were measured. In predicting poor outcomes, the prognostic performance of relevant CT parameters was evaluated, and the comparison analysis(expressed as the ratio of parameters in late CT to those in the early CT) of different CT time was conducted. RESULTS: Totally 26 patients were in the good-outcome group, while 68 patients were in the poor-outcome group. The putamen density, GWR, and pCSFV in late CT were significantly lower in the poor-outcome group(P<0.05). The ratios of GWR and pCSFV in the poor-outcome group were significantly decreased according to comparison analysis of different CT time(P<0.05), while there was no significant difference in the ratio of putamen density. GWR-basal ganglia <1.18 in late CT showed the best predictive value. The ratio of pCSFV <0.98 predicted unfavorable neurological outcomes with a sensitivity of 65.9% and a specificity of 93.8%(P=0.001).CONCLUSIONS: Brain CT performed >24 h after CA may be a good choice as a neuroimaging approach to evaluating prognosis. To predict neurological prognosis, comparison analysis of different CT time can be used as another promising tool in comatose CA survivors.