Optimal timing of ultra-early diffusion-weighted MRI in out-of-hospital cardiac arrest survivors: A retrospective multicenter cohort study

Abstract Diffusion-weighted magnetic resonance imaging (DW-MRI) performed before target temperature management (TTM), within 6 h of return of spontaneous circulation (ROSC), is defined as ultra-early DW-MRI. In previous studies, high-signal intensity (HSI) on ultra-early DW-MRI can predict poor neurological outcomes. We evaluated the optimal timing for ultra-early DW-MRI to avoid false-negative findings in out-of-hospital cardiac arrest (OHCA), considering cardiopulmonary resuscitation (CPR) factors. The primary outcomes were HSI in the cerebral cortex or deep gray matter on ultra-early DW-MRI. The impact of CPR factors and ROSC to DW-MRI scan-interval on HSI-presence was assessed. Of 206 included patients, 108 exhibited HSI-presence, exclusively associated with poor neurological outcomes. In multivariate regression analysis, ROSC to DW-MRI scan-interval (adjusted odds ratio [aOR], 1.509; 95% confidence interval (CI): 1.113–2.046; P = 0.008), low-flow time (aOR, 1.176; 95%CI: 1.121–1.233; P < 0.001), and non-shockable rhythm (aOR, 9.974; 95%CI: 3.363–29.578; P < 0.001) were independently associated with HSI-presence. ROSC to DW-MRI scan-interval cutoff of ≥ 2.2 h was particularly significant in low-flow time ≤ 21 min or shockable rhythm group. Short low-flow time and shockable rhythm require a longer ROSC to DW-MRI scan-interval. Prolonged low-flow time and non-shockable rhythm reduce the need to consider scan-interval.