Radiological Phenotypes of Acute Brain Injury During Extracorporeal Membrane Oxygenation on Ultra-Low-Field Portable MRI

Background Despite the clinical importance of acute brain injury (ABI) during extracorporeal membrane oxygenation (ECMO), the mechanism of ECMO-associated ABI remains poorly understood, partly because conventional magnetic resonance imaging (MRI) is incompatible with ECMO devices. Ultra-low-field portable MRI (ULF-pMRI) enables high-quality bedside neuroimaging during ECMO. We aimed to characterize imaging phenotypes of ABI and explore mechanisms underlying lesion distribution across ECMO configurations. Methods In this multicenter retrospective observational study, adults receiving ECMO who underwent bedside ULF-pMRI at Johns Hopkins University and University of Texas–Houston from December 2021 to May 2026 were included. ABI was defined as ischemic stroke (IS), intraparenchymal hemorrhage (IPH), subarachnoid hemorrhage (SAH), or subdural hematoma (SDH). Lesions were characterized according to vascular territory, cortical/subcortical lesion versus deep white matter (WM)/basal ganglia (BG) involvement, laterality, lesion burden, and cerebral small-vessel disease (SVD) using Fazekas scale. Associations between ECMO configuration (central venoarterial [VA], peripheral VA, and venovenous [VV]), echocardiographic findings, and ECMO parameters were examined. Results Among 70 patients analyzed (55.9 ± 16.2 years; 54.3% male), 29 (41.4%) had ABI. IS was the predominant type of ABI (82.8%), with most strokes affecting the frontal lobe (48.3%). All the central VA-ECMO patients with ABI demonstrated predominantly cortical/subcortical lesions, whereas deep WM/BG involvement was more frequent in peripheral VA-ECMO (53.8%). Peripheral VA-ECMO demonstrated left hemispheric predominance (85% vs. 15% right-sided, P =0.002), and deep WM/BG lesions in peripheral were associated with higher ECMO pump flow and lower pulse pressure. Among VV-ECMO patients, bilateral lesions were more common (62.5%), with a high prevalence of deep WM/BG involvement (62.5%) and SVD (75%). Conclusions ULF-pMRI revealed distinct radiological phenotypes of ABI across ECMO configurations; cortical/subcortical lesions in central VA-ECMO, left-sided predominance in peripheral VA-ECMO and frequent deep WM/BG in VV-ECMO. These findings generate mechanistic hypotheses regarding configuration-specific pathways of ABI and may inform future strategies for risk stratification, prevention and monitoring.