Assessing Brain Injury Using Portable Magnetic Resonance Imaging (MRI)

Extracorporeal membrane oxygenation (ECMO) is a life-saving therapy increasingly used in patients with refractory cardiopulmonary failure. The Extracorporeal Life Support Organization (ELSO) registry recently reported a 58% survival rate among patients who receive ECMO support, showing a significant mortality benefit in patients who would have not survived without ECMO. However, acute brain injury (ABI) is common in patients with ECMO support and leads to devastating consequences with significant morbidity and mortality. The mortality increases more than two-fold when ABI is present for both venoarterial (VA) and venovenous (VV) ECMO patients. The poor prognosis of ABI and neurological complications would suggest potential benefit from stringent and possibly even protocolized neurological monitoring to prevent or minimize further harm. This is particularly important as recent evidence promotes extracorporeal cardiopulmonary resuscitation (ECPR) as a rescue therapy for patients suffering from cardiac arrest of potentially reversible etiology. As clinical experience accumulates and ECPR becomes more widely used, neurological monitoring for complications and prognostication will be imperative for optimizing patient outcomes.

Although standardized neurological monitoring improves the detection of ABI, timely diagnosis and management for ABI in patients with ECMO support is still challenging due to the difficulty, impracticality, and danger of transporting ECMO patients to a CT scanner. Often, ECMO patients are unable to be transported to radiology suites because of the patients' persistent cardiopulmonary instability with multiple vasopressor requirements. In addition, even if head CT is performed in these patients, it is limited by poor sensitivity for detecting acute ischemic brain injury. Early neuroimaging is a key neuromonitoring aspect in the clinical evaluation of ABI. However, conventional magnetic resonance imaging (MRI) systems operate at high magnetic field strengths (1.5-3T) that require strict, access-controlled environments. Thus, limited access to timely brain scan with images of sufficient quality remains a significant barrier to effectively monitoring the occurrence and progression of ABI in ECMO.

Recent advances in low-field and portable MRI technology have enabled the acquisition of clinically meaningful imaging in the presence of ferromagnetic materials. A very low magnetic field strength, 64 magnetization transfer (mT), approximately 1/23 the field strength of a conventional MRI) provides a 5 Gauss line (safety zone) that is only about 2.5 feet from the center of the scanner. In a previous report, researchers were able to demonstrate the feasibility of a low-field, portable MRI in complex clinical care settings, such as intensive care units, without any adverse events or complications. In addition to reduced projectile motion, the use of low-field MRI may mitigate other safety concerns associated with high-field MRI, such as peripheral nerve stimulation (from gradients), a radiofrequency absorption and heating and acoustic noise.

The objective of this study is to assess acute brain injury with low-field, portable MRI of brain in patients with ECMO support.

This study will use the Hyperfine portable MRI machine which has FDA 510(k) clearance and is intended for use in intensive care units. The investigators' hypothesis is that low-field, portable MRI can detect ABI in patients with ECMO support, which may decrease the morbidity of patients on ECMO.

Inclusion criteria

• Adults age 18 and over
• Patient supported with extracorporeal membrane oxygenation support (ECMO)
• Legally authorized representative has provided written informed consent

Exclusion criteria

• Patient has a contraindication for MRI such as:
• Implants such as pacemaker, defibrillator, implanted insulin pump, deep brain stimulator, vagus nerve stimulator, cochlear implant, or programmable shunt
• MRI incompatible surgical hardware such as staples, screws. ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, cochlear implant
• artificial hearts or heart valves with steel parts
• metal fragments
• shrapnel
• tattoos near the eye
• permanent make-up
• steel implants
• or other irremovable ferromagnetic objects
• Patient weight is over 440 lbs (or 200kg)
• Patient has Intra Aortic Balloon Pump (IABP), Implanted Ventricular Assist Device (VAD), or Percutaneous Ventricular Assist Device
• Patient is pregnant