Detection of cerebral ischemic injury during extracorporeal membrane oxygenation using microvascular flows measured by ultrasound localization microscopy

Abstract

Pediatric Extracorporeal Membrane Oxygenation (ECMO) is a life-saving therapy. Affecting 8–50% of patients, brain injury is among the most frequent complications. Non-invasive monitoring of brain perfusion during ECMO using contrast-enhanced ultrasound imaging can potentially improve the outcome. Here we utilize an in-house developed Ultrasound Localization Microscopy (ULM) procedure, which involves a super-resolution deep learning approach for subpixel localization of microbubbles and Kalman filter-based bubble tracking, to measure the brain blood perfusion in a pediatric pig model during ECMO. Parameters, including the mean velocity magnitude in large (>1mm) and medium (0.2–1 mm) vessels, as well as the cerebral microcirculation for micro (<0.2 mm) vessels, are analyzed and compared with the histological readings of brain ischemic injury levels. Data show significantly reduced micro perfusion in the cortex and thalamus with increasing levels of ischemic injury. Compared with large and medium vascular flows, microvascular flows are more sensitive in not only detecting injury but also evaluating injury levels. These results suggest that the management of ECMO patients could be guided by and benefit from the non-invasive monitoring of cerebral microvascular flows.