Ultralow-field portable MRI feasibility and safety in pediatric and neonatal ECMO: a single center year-long experience

Introduction

Extracorporeal membrane oxygenation (ECMO) outcomes continue to improve, yet high rates of acute brain injury (ABI) threaten survival with significant morbidity for ECMO survivors. Currently available imaging modalities [ultrasound and computed tomography (CT)] have low early detection rates for hypoxic-ischemic and cerebrovascular injuries, delaying the diagnosis of ABI while on ECMO. CT sensitivity increases only when it may be too late to effectively intervene. High-field (>1.5 Tesla) magnetic resonance imaging (MRI), the gold standard to diagnose ischemic brain injury, is not compatible with ECMO. An FDA-cleared ultralow-field (0.064 Tesla) portable MRI (pMRI) has been studied in diverse types of ABI and with equipment that is typically not MRI compatible. There is very limited experience using pMRI in ECMO and even less in pediatric ECMO patients, therefore additional feasibility and safety data is needed in this cohort.

Methods

This single center, IRB approved study was conducted at a free-standing quaternary children’s hospital. All neonatal and pediatric patients cannulated onto ECMO were screened for eligibility. Subjects underwent bedside ultralow-field pMRI with Swoop (Hyperfine, Guilford, CT). Data on ECMO variables, time for patient positioning and scan, MRI sequences, concurrent critical care equipment, changes in ECMO flow and vital signs, and cannula displacement was collected.

Results

Over a 1-year period (Aug 2023-Aug 2024) 41 patients were screened. 16 out of 20 enrolled subjects had pMRI attempted and 13 (81.25%) received the full imaging protocol (T1, T2, FLAIR and DWI). The median staff members for pMRI positioning was 6 [5, 7] compared to 7 [7,7] for head CT (0.03). The median positioning and pMRI imaging time was 66 min [56, 70] compared to 75 min [70,79] for intrahospital transport for head CT. One subject had a ≥ 20% decrease in mean arterial pressure, however remained within the clinical goals without intervention. Unlike during head CT imaging acquisition, continuous renal replacement therapy was not interrupted during pMRI.

Conclusions

pMRI is safe and feasible in pediatric ECMO with no clinically relevant complications seen in our cohort. Resource utilization and delivery of concurrent critical care is superior for bedside imaging compared to intrahospital transport to CT.

Clinical Trial Registration

NCT06074406 https://clinicaltrials.gov/study/NCT06074406?term=NCT06074406Crank=1

CLINICAL PERSPECTIVE

What are the clinical implications?

• Ultralow-field portable MRI can expand time-sensitive head imaging options for pediatric patients on ECMO with less interruptions of critical care therapies, decreased resource utilization, and eliminated risks of travel and radiation exposure.

• Timely diagnosis of acute brain injury while on ECMO can prompt changes in neuromonitoring, anticoagulation management, and delivery of neuroprotective care with the intent to improve neurologic outcomes of pediatric ECMO survivors.