Taking the Mystery out of MRI
December 14th, 2024 | Care
| Research
Understanding the Role of MRI in Neonatal HIE
When a newborn is diagnosed with Hypoxic-Ischemic Encephalopathy (HIE), parents often hear about a test called a MRI (Magnetic Resonance Imaging). This test is frequently used to evaluate the brain and guide care decisions, but it’s important to understand its benefits, limitations, and role in managing HIE.
What is a MRI?
MRI is a non-invasive imaging test that uses powerful magnets and radio waves to create detailed pictures of the brain. Unlike X-rays or CT scans, it does not use radiation, making it safe for infants.
In cases of HIE, a MRI can:
- Show areas of the brain that may have been injured.
- Help predict neurodevelopmental outcomes.
- Guide medical teams in planning treatments and interventions.
Why is MRI Important in HIE?
Neonatal HIE happens when a baby’s brain doesn’t get enough oxygen or blood flow before, during or around the time of birth. This lack of oxygen can cause damage to certain parts of the brain, but the extent and location of the damage can vary widely.
A MRI can help answer key questions, such as:
- Where is the injury? Specific areas of the brain may be more affected than others.
- How severe is the injury? MRI results may show how extensive the damage is.
- What might this mean for the future? While no test can predict the future with certainty, MRI findings can provide clues about potential developmental challenges or strengths.
When is a MRI Performed?
In most cases, an MRI is done within the first 4-7 days after birth. This timing allows doctors to see the full picture of the brain’s condition. Sometimes, a follow-up MRI is done weeks or months later to track changes or assess healing. However, a MRI finding may not correlate to outcome, because it is one piece of a very complex puzzle.
Predictive Value of MRI in HIE
Research studies, such as the HEAL (High-Dose Epo for Asphyxia and Encephalopathy) trial, have helped refine the understanding of MRI’s predictive value in neonatal HIE. These studies suggest that MRI findings, particularly when performed in the first week of life, can:
- Provide important insights into the likely extent of neurodevelopmental challenges.
- Identify patterns of injury associated with specific outcomes, such as motor or cognitive delays.
For example, MRIs showing significant injury in the basal ganglia and thalamus are most often linked to motor impairments, while damage to the white matter may correlate with cognitive or behavioral challenges. However, these predictions are not absolute, and outcomes can vary depending on factors like early interventions and the brain’s capacity for neuroplasticity.
The HEAL study analyzed MRI results from the cohort and showed MRI prediction was accurate about 50% of the time, with the highest accuracy predicting severe outcomes with severe HIE.
Limitations of MRI
While MRI is a powerful tool, it’s not perfect. Here are some important limitations to keep in mind:
- Timing and Healing:
- Brain injury evolves over time. A MRI done very early may not show the full extent of damage.
- The brain has a remarkable ability to heal, especially in newborns. MRI findings might not always predict long-term outcomes.
- Not the Whole Story:
- MRI shows structural changes in the brain but doesn’t measure how the brain functions. A child’s development depends on many factors, including therapy, family support, and resilience.
- Variability in Outcomes:
- Two babies with similar MRI results might have different developmental outcomes. MRI is just one piece of the puzzle.
- Pseudonormalization of MRI Findings:
- In some cases, MRI findings can appear “normal” over time, even when there has been significant injury. This is known as pseudonormalization and occurs because the injured areas of the brain may change in appearance as they heal or adapt. This phenomenon underscores the importance of combining MRI results with other evaluations, such as developmental assessments and ongoing clinical observations.
What Parents Should Know
- Ask Questions: Don’t hesitate to ask your medical team to explain MRI results in simple terms. Understanding what the images show can help you feel more informed.
- Focus on the Big Picture: MRI is a helpful tool, but it’s not the final word on your child’s future. Many factors influence development, and every child’s journey is unique.
- Plan for the Future: Use MRI results in the context of neurodevelopment in therapies and interventions. Early support can make a big difference in long-term outcomes.
A Message of Hope
HIE can be a challenging diagnosis, but it’s important to remember that the brain is incredibly adaptable, especially in young children. While an MRI provides valuable information, it’s just one part of the care and support your child will receive. By working closely with your medical team and engaging in therapies and interventions, you can help your child reach their fullest potential.
Want to read more about HIE and MRI?
- Diffusion Pseudonormalization and Clinical Outcome in Term Neonates With Hypoxic-Ischemic Encephalopathy. Hayakawa K, Koshino S, Tanda K, et al.Pediatric Radiology. 2018;48(6):865-874. doi:10.1007/s00247-018-4094-z.
- Impact of Therapeutic Hypothermia on MRI Diffusion Changes in Neonatal Encephalopathy. Bednarek N, Mathur A, Inder T, et al.Neurology. 2012;78(18):1420-7. doi:10.1212/WNL.0b013e318253d589.
- Apparent Diffusion Coefficient Pseudonormalization Time in Neonatal Hypoxic-Ischemic Encephalopathy. Winter JD, Lee DS, Hung RM, et al.Pediatric Neurology. 2007;37(4):255-62. doi:10.1016/j.pediatrneurol.2007.06.005.
- Differences Between Early and Late MRI in Infants With Neonatal Encephalopathy Following Therapeutic Hypothermia. Garvey AA, El-Shibiny H, Yang E, Inder TE, El-Dib M.Pediatric Research. 2023;94(3):1011-1017. doi:10.1038/s41390-023-02580-8.
- Early Versus Late Brain Magnetic Resonance Imaging After Neonatal Hypoxic Ischemic Encephalopathy Treated With Therapeutic Hypothermia. O’Kane A, Vezina G, Chang T, et al.The Journal of Pediatrics. 2021;232:73-79.e2. doi:10.1016/j.jpeds.2021.01.050.