Association of ultra-early diffusion-weighted magnetic resonance imaging with neurological outcomes after out-of-hospital cardiac arrest

BACKGROUND: This study aimed to investigate the association between ultra-early (within 6 h after return of spontaneous circulation [ROSC]) brain diffusion-weighted magnetic resonance imaging (DW-MRI) and neurological outcomes in comatose survivors after out-of-hospital cardiac arrest. METHODS: We conducted a registry-based observational study from May 2018 to February 2022 at a Chungnam national university hospital in Daejeon, Korea. Presence of high-signal intensity (HSI) (P(HSI)) was defined as a HSI on DW-MRI with corresponding hypoattenuation on the apparent diffusion coefficient map irrespective of volume after hypoxic ischemic brain injury; absence of HSI was defined as A(HSI). The primary outcome was the dichotomized cerebral performance category (CPC) at 6 months, defined as good (CPC 1–2) or poor (CPC 3–5). RESULTS: Of the 110 patients (30 women [27.3%]; median (interquartile range [IQR]) age, 58 [38–69] years), 48 (43.6%) had a good neurological outcome, time from ROSC to MRI scan was 2.8 h (IQR 2.0–4.0 h), and the P(HSI) on DW-MRI was observed in 46 (41.8%) patients. No patients in the P(HSI) group had a good neurological outcome compared with 48 (75%) patients in the A(HSI) group. In the A(HSI) group, cerebrospinal fluid (CSF) neuron-specific enolase (NSE) levels were significantly lower in the group with good neurological outcome compared to the group with poor neurological outcome (20.1 [14.4–30.7] ng/mL vs. 84.3 [32.4–167.0] ng/mL, P < 0.001). The area under the curve for P(HSI) on DW-MRI was 0.87 (95% confidence interval [CI] 0.80–0.93), and the specificity and sensitivity for predicting a poor neurological outcome were 100% (95% CI 91.2%–100%) and 74.2% (95% CI 62.0–83.5%), respectively. A higher sensitivity was observed when CSF NSE levels were combined (88.7% [95% CI 77.1–95.1%]; 100% specificity). CONCLUSIONS: In this cohort study, P(HSI) findings on ultra-early DW-MRI were associated with poor neurological outcomes 6 months following the cardiac arrest. The combined CSF NSE levels showed higher sensitivity at 100% specificity than on DW-MRI alone. Prospective multicenter studies are required to confirm these results. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13054-023-04305-z.