Multi-Center Study of Diffusion-Weighted Imaging in Coma After Cardiac Arrest

Background: The ability to predict outcomes in acutely comatose cardiac arrest survivors is limited. Brain diffusion-weighted magnetic resonance imaging (DWI MRI) has been shown in initial studies to be a simple and effective prognostic tool. This study aimed to determine the predictive value of previously defined DWI MRI thresholds in a multi-center cohort. Methods: DWI MRIs of comatose post-cardiac arrest patients were analyzed in this multi-center retrospective observational study. Poor outcome was defined as failure to regain consciousness within 14 days and/or death during the hospitalization. The apparent diffusion coefficient (ADC) value of each brain voxel was determined. ADC thresholds and brain volumes below each threshold were analyzed for their correlation with outcome. Results: 125 patients were included in the analysis. 33 patients (26 %) had a good outcome. An ADC value of less than 650 × 10⁻⁶ mm²/s in ≥10 % of brain volume was highly specific [91 % (95 % CI 75–98)] and had a good sensitivity [72 % (95 % CI 61–80)] for predicting poor outcome. This threshold remained an independent predictor of poor outcome in multivariable analysis (p = 0.002). An ADC value of less than 650 × 10⁻⁶ mm²/s in >22 % of brain volume was needed to achieve 100 % specificity for poor outcome. Conclusions: In patients who remain comatose after cardiac arrest, quantitative DWI MRI findings correlate with early recovery of consciousness. A DWI MRI threshold of 650 × 10⁻⁶ mm²/s in ≥10 % of brain volume can differentiate patients with good versus poor outcome, though in this patient population the threshold was not 100 % specific for poor outcome.