ABSTRACT

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.

What is new?

This study expands the experience of ultralow-field portable MRI to pediatric ECMO patients.

Ultralow-field portable MRI is feasible and less resource-intense to perform on pediatric ECMO patients compared to intrahospital transport for head CT.

Pediatric ECMO patients tolerate bedside MRI without clinically significant changes in ECMO flows, perfusion, or oxygenation.

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.

Competing Interest Statement

This study was investigator initiated and no funding was provided by Hyperfine, Inc. however the Children's Mercy Research Institute has received in kind and research contracts from Hyperfine, Inc.

Funding Statement

JSW is supported by the American Heart Association Grant #24IPA1272935/Wallisch/2024 for her work on portable MRI in pediatric ECMO.

Author Declarations

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

IRB of Children's Mercy Hospital gave ethical approval for this work.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

Data Availability

Data is available upon reasonable request.

Non-standard Abbreviations and AcronymsECMOextracorporeal membrane oxygenationABIacute brain injuryCTcomputed tomographyMRImagnetic resonance imagingpMRIportable magnetic resonance imagingFDAFood and Drug AdministrationTTeslaVVvenovenousVAvenoarterialELSOExtracorporeal Life Support OrganizationICNIntensive Care NurseryPICUPediatric Intensive Care UnitCICUor Cardiac Intensive Care UnitFLAIRFluid-attenuated inversion recoveryDWIdiffusion-weighted imagingEEGelectroencephalogramCRRTcontinuous renal replacement therapy