Abstract 314: Changes In The Hounsfield Unit Proportion Of Head Computed Tomography With Time And Neurological Outcomes In Out-of-hospital Cardiac Arrest Survivors

Abstract

Changes in the Hounsfield Unit proportion of head computed tomography with time and neurological outcomes in out-of-hospital cardiac arrest survivors Aim: We compared changes in Hounsfield Unit proportion (HUp) with neurological outcomes using head computed tomography (HCT) obtained before and after targeted temperature management of out-of-hospital cardiac arrest (OHCA) survivors. Methods: This retrospective observational study included adult comatose OHCA survivors who underwent HCT scans within 6 h (first HCT) and 72-96 h (second HCT) after the return of spontaneous circulation (ROSC). Automated quantitative analysis using non-enhanced HCT images was applied to identify the difference in HU value distribution across the intracranial area between neurological outcomes. Each pixel in an HCT image has a certain HU level, λ, which is between 1 and 79 in this study. The proportion (%) of λ in a CT image is 0 to 100, with the sum of every λp as 100, as per the definition of λp. The primary outcome was the 6-month poor (CPC 3-5) outcome. Results: Of the 41 included patients (30 males; 73%), 14 (34%) had poor outcomes. In the first HCT, only HU = 29-30 showed a difference according to the neurological outcome; however, in the second HCT, HU = 1-12, 22-33, 39-50 showed a difference ( P < 0.05) (Fig. 1). Among them, the greatest difference between the good and poor neurological outcome groups was the proportion of pixels with HU = 22-33, and the average values were 36.0 ± 6.0 and 43.6 ± 8.1, respectively ( P < 0.01). In addition, receiver operating characteristic analysis showed that the of the second HCT was predictive of prognostic performance from poor neurological outcomes six months after ROSC to moderate to good (0.76; 95% confidence interval, 0.60-0.88). Conclusions: The proportion of in total cerebral regions in HCT scans obtained between 72-96 hours after ROSC in OHCA survivors was associated with poor neurological outcomes six months after ROSC.