Cerebral Ischemic Injury during Extracorporeal Membrane Oxygenation Detected by Ultrasound Localization Microscopy of the Microvascular Flow

Affecting 8–50% of patients, ischemic brain injury is among the most frequent complications in patients undergoing pediatric Extracorporeal Membrane Oxygenation (ECMO). Non-invasive monitoring of brain perfusion during ECMO using contrast-enhanced ultrasound imaging could potentially improve this outcome. Here we utilize an in-house developed Ultrasound Localization Microscopy (ULM) procedure, which involves super-resolution deep learning with a subpixel localization accuracy of bubble centers, followed by Kalman filter-based bubble tracking, to map the cerebral circulation in a pediatric pig model during ECMO. Parameters, including the mean velocity magnitude in large (>1mm) and medium (0.2-1mm) blood vessels, as well as the microcirculation in micro (<0.2mm) vessels, are compared to histological data of the levels of brain ischemia. Results show significantly decreased micro perfusion in the cortex and thalamus with increasing ischemic injury level. The microvascular flows are more sensitive than those in the larger vessels, not only in detecting injury but also in evaluating the injury level. These findings suggest that the management of ECMO patients could be guided by and benefit from the non-invasive monitoring of cerebral microvascular flows.