MRI is used for numerous reasons during work up of symptoms in the neonatal period.
Advantages over CT include no ionizing radiation, improved sensitivity for evaluation of infarction and white matter changes and advanced imaging techniques that may help with prognostication (MR spectroscopy and diffusion tensor imaging (DTI).
-More common indications include neonatal encephalopathy, acquired brain injury, etiology of neonatal seizures, hypoxic ischemic encephalopathy (HIE), congenital malformations, focal cerebral injury including arterial and venous stroke, intracranial hemorrhage, toxic and metabolic disorders, bilirubin encephalopathy, birth trauma and evaluation of neonatal meningitis.
- May have a role in pre and post-operative evaluation of brain in neonates with congenital heart diseases (CHD), particularly high risk infants with CHD.
Jansen, F. A. R. et al, (2016) Fetal brain imaging in isolated congenital heart defects – a systematic review and meta-analysis. Prenat Diagn, 36: 601–613. doi: 10.1002/pd.4842.
Khalil A et al. Brain abnormalities and neurodevelopmental delay in congenital heart disease: systematic review and meta-analysis. Ultrasound Obstet Gynecol 2014;43:14-24.
- May have a role in determining brain insult following decannulation of extra corporeal membrane oxygenation (ECMO) in patients with neurological signs.
Rollins MD et al. Utility of neuroradiographic imaging in predicting outcomes after neonatal extracorporeal membrane oxygenation. J Pediatr Surg. 2012;47:76-80.
- May have a role in predicting neurodevelopmental outcomes in preterm neonates when performed at term equivalent age.
Kwon, SH et al, Role of Neuroimaging in Predicting Neurodevelopmental Outcomes of Preterm Neonates. DOI: http://dx.doi.org/10.1016/j.clp.2013.10.003
Thayyil S. et al., Cerebral magnetic resonance biomarkers for predicting neurodevelopmental outcome following neonatal encephalopathy: a meta-analysis. Pediatrics. 2010;125(2). Available at: www.pediatrics.org/cgi/ content/full/125/2/e382. And Hintz SR, Barnes PD, Bulas D, et al. Neuroimaging and Neurodevelopmental Outcome in Extremely Preterm Infants. Pediatrics. 2015;135(1):e32-e42. doi:10.1542/peds.2014-0898.
- Role in prognosis in HIE, particularly with MR spectroscopy, ideally performed between 5-14 day of life.
Barkovich AJ et al, MR imaging, MR spectroscopy, and diffusion tensor imaging of sequential studies in neonates with encephalopathy. Am J Neuroradiol. 2006;27:533- 47
- Anatomical detail of spine malformations
-Hemangiomas and vascular malformations, helpful for lesion characterization and anatomic extent of lesion.
-Congenital cystic masses of the head and neck region.
-Mediastinal vascular anomalies – rings and slings. MRI is useful for demonstrating vascular anatomy and relationship to airway without the use of intravenous contrast, as well as for creation of 3D reconstructions.
-Anatomic delineation of congenital pelvic GI/GU anomalies, role for MRI for anatomic clarification in some cases.
-Neoplastic and other masses of the neonatal period
Motion limitations and length of study.
Feasibility of patient transport to MRI scanner, particularly in a fragile neonate.
Monitoring NICU patient in the scanner and MR environment with MR safe equipment.
Optimization of neonatal MRI parameters particularly in machines with older software.
Vacuum immobilizer and feed and bundle
Haney, B. et al, Magnetic Resonance Imaging Studies Without Sedation in the Neonatal Intensive Care Unit Safe and Efficient. J Perinat Neonat Nurs Vol. 24, No. 3, pp. 256–266.
Safety Guidelines for Magnetic Resonance Imaging Equipment in Clinical Use
http://www.ismrm.org/smrt/files/con2033065.pdf
ACR Guidance on MR Safe Practices: 2013 http://onlinelibrary.wiley.com/doi/10.1002/jmri.24011/pdf
Anesthesia research in pediatrics http://smarttots.org/
To avoid sedation or general anesthesia, several sites do “feed and wrap/feed and bundle” technique in infants typically less than 3 months with swaddling and optional pacifier with or without oral sucrose solution. Sedation may be necessary if these methods fail. There are several standards of care mandates from AAP, ASA, JAHCO pertaining to neonatal sedation, as well as new research about potential dangers of infant sedation.
Harrison D et al, Efficacy of sweet solutions for analgesia in infants between 1 and 12 months of age: a systematic review. Archives of Disease in Childhood 2010; 95(6): 406-413.
Vitals and thermoregulation: Physiological monitoring, including oxygen saturation, blood pressure, end tidal carbon dioxide and heart rate, is suggested. Temperature control especially in preterm infants is important. Infants are prone to hypothermia in the scanner environment. This in turn can lead to heat loss and depletion of fragile metabolic infant reserve.
Battin, M. et al, Physiological stability of preterm infants during magnetic resonance imaging, Early Human Development, Volume 52, Issue 2, 1 September 1998, Pages 101-110, ISSN 0378-3782, http://dx.doi.org/10.1016/S0378-3782(98)00024-3.
Plaisier A et al. Safety of routine early MRI in preterm infants. Pediatric Radiology. 2012;42(10):1205-1211. http://dx.doi:10.1007/s00247-012-2426-y
MR safe monitoring and anesthetic equipment and MR compatible transport equipment are a must. Personnel must pay close attention to endotracheal tubes, ventilation machines, artifacts from small portions of metals in intravenous and central venous catheters and also make distinction between MR safe (no ferromagnetic material, but may malfunction in the magnetic field) vs. MR compatible (unaffected by the magnetic field) equipment. ECG leads, pulse oximeter, ventilation equipment (with extra-long tubing if required), and infusion pumps should be MR compatible.
Mathur, A.M. et al, Transport, monitoring, and successful brain MR imaging in unsedated neonates. Pediatr Radiol (2008) 38: 260. http://dx.doi:10.1007/s00247-007-0705-9
MR compatible incubator are available with or without built in neonatal RF coils to provide superior image quality, as well as to ensure better physiological stability. Vacuum immobilizer device can be used to decrease motion artifact and potentially eliminate risk of sedation.
Paley M. et al, An MR-compatible neonatal incubator. The British Journal of Radiology. 2012;85(1015):952-958. http://dx.doi:10.1259/bjr/30017508
Haney, B. et al, Magnetic Resonance Imaging Studies Without Sedation in the Neonatal Intensive Care Unit Safe and Efficient. J Perinat Neonat Nurs Vol. 24, No. 3, pp. 256–266.
Dedicated neonatal intensive care unit MRI units are being developed in a few centers around the world. A small footprint MRI developed in Cincinnati Children’s hospital is being used clinically and has various advantages. Tkach, J. et al, MRI in the Neonatal ICU: Initial Experience Using a Small-Footprint 1.5-T System. American Journal of Roentgenology 2014 202:1, W95-W105
Gadolinium in newborn: Gadobutrol (Gadavist®) approved for use in magnetic resonance imaging “to detect and visualize areas with disrupted blood brain barrier (BBB) and/or abnormal vascularity of the central nervous system in pediatric patients less than 2 years of age (including term neonates).” https://www.radiologysolutions.bayer.com/products/mr/contrast/gadavist/
Other uses are off label in neonates. Neonates have immature renal function and remain at higher theoretical risk for nephrogenic systemic fibrosis.
http://www.acr.org/Quality-Safety/Resources/Contrast-Manual - ACR Manual on Contrast Media
Gadolinium deposition is known to occur. However, to date, no signs or symptoms of adverse health effects and no pathological changes have been associated with these gadolinium deposits in the brain. FDA investigating risk of brain deposits following repeated GBCA (Gadolinium based MR contrast agents).
http://www.fda.gov/Drugs/DrugSafety/ucm455386.htm
Biomedical implant hazards: as with all MRI evaluations, MR compatibility of implanted medical devices should be checked. Manufacturer guidelines must be followed if device is MR conditional.
Biomedical implant hazards, Institute for Magnetic Resonance Safety, Education and Research
http://www.mrisafety.com
This a potential noise hazard with MRI. Prolonged exposure to noise levels above 85 decibels can lead to hearing loss with much shorter durations of exposure required at higher decibels. Use of earplugs, headphones and/or earmuffs is being universal. Several MR vendors now offer noise reduction technology.
McJury PhD, M. and Shellock PhD, F. G. (2000), Auditory Noise Associated With MR Procedures: A Review. J. Magn. Reson. Imaging, 12: 37–45. doi:10.1002/1522-2586(200007)12:1<37::AID-JMRI5>3.0.CO;2-I..
Gradient magnetic field effects can induce currents in conductive tissues of the body, which in theory can lead to peripheral nerve stimulation or even cardiac stimulation although these are not observed during routine clinical MRI.
Radiofrequency (RF) pulse related power deposition and tissue heating, especially in patients with poor thermoregulatory control can occur. Specific absorption rate is the rate at which RF field deposits energy. Local temperature fluctuations are difficult to predict. SAR limits 3.2 W/kg over 10 minutes for head and 4 W/kg for body. Additional attention must be given to ensure MR compatibility of monitoring equipment, which may heat and cause skin burns such as pulse oximetry monitors and EKG leads. http://www.fda.gov/downloads/medicaldevices/deviceregulationandguidance/guidancedocuments/ucm072688.pdf
Emergencies in MR suite may arise and proper protocol for emergent evacuation of sick infant from the scanner room for resuscitation should be in place. Policies to guide safe handling of patient and personnel in the event of a quench during an MR examination should also be in place.
Safety of any accompanying family member or medical personnel, including hearing protection and screening for implantable devices, is mandatory.
MRI of the neonatal brain by Mary A Rutherford
http://www.mrineonatalbrain.com/
British Association of Perinatal Medicine: Fetal and Neonatal Brain Magnetic Resonance Imaging: Clinical Indications, Acquisitions and Reporting, A Framework for Practice
http://www.bapm.org/publications/documents/guidelines/BAPM%20MRI%20standards%20for%20fetal%20neonatal%20brain%20imaging_FINAL%20SUBMISSION%20080216.pdf
Safety Guidelines for Magnetic Resonance Imaging Equipment in Clinical Use
http://www.ismrm.org/smrt/files/con2033065.pdf
Biomedical implant hazards, Institute for Magnetic Resonance Safety, Education and Research
http://www.mrisafety.com/
HIE work up recommendations for HIE
http://emedicine.medscape.com/article/973501-workup#c5
Practice Parameters ACR
https://www.acr.org/~/media/ACR/Documents/PGTS/standards/MonitorMRIEquipment.pdf
https://www.acr.org/~/media/ACR/Documents/PGTS/guidelines/Skeletal_Surveys.pdf
Tocchio, S. et al, MRI evaluation and safety in the developing brain, Seminars in Perinatology, Volume 39, Issue 2, March 2015, Pages 73-104, ISSN 0146-0005. http://dx.doi.org/10.1053/j.semperi.2015.01.002.
Arthurs, O.J. et al, Challenges of neonatal MRI, Pediatr Radiol (2012) 42: 1183. doi:10.1007/s00247-012-2430-2
Updated Classification of Pediatric Vascular Anomalies/Terminology
Kollipara R, Dinneen L, Rentas KE, et al. Current Classification and Terminology of Pediatric Vascular Anomalies. AJR 2013; 201:1124–1135. DOI:10.2214/AJR.12.10517
Guidelines for Staging of Neuroblastic Tumors
Brisse HJ, McCarville MB, Granata C, et al. Guidelines for Imaging and Staging of Neuroblastic Tumors: Consensus Report from the International Neuroblastoma Risk Group Project. Radiology 2011; 261:243-257. DOI: 10.1148/radiol.11101352