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PubMed This is a summary of 4 peer-reviewed journal articles Updated
Neurology

The Screening MRI: Why and When to Image

At a Glance

A screening MRI for neurocutaneous melanocytosis (NCM) should ideally be performed before an infant is 6 months old. At this age, lack of brain myelin makes melanin deposits easier to see. However, accurate scans can still be done in older patients using contrast dye.

If you or your child is in a high-risk category due to the size or number of birthmarks, your medical team may recommend a screening Magnetic Resonance Imaging (MRI) scan. This test is the most reliable way to identify melanin (pigment) deposits in the brain or spinal cord [1][2].

The Importance of the 6-Month Window for Infants

For infants, doctors strongly prefer to perform this screening before 6 months of age [1]. At birth, a baby’s brain is still developing a fatty protective coating around the nerves called myelin [3].

  • Before 6 Months: Melanin has a unique property called T1 shortening, which means it shows up as a bright, high-intensity signal (white spots) on a T1-weighted MRI scan [2]. Because the infant brain hasn’t fully myelinated yet, the surrounding brain tissue looks darker, making these bright melanin spots very easy to see [3].
  • After 6 Months: As myelination increases, the rest of the brain tissue also begins to look bright on the scan [3]. This can create a “camouflage” effect, making the melanin deposits much harder to detect [3].

Scans for Older Children and Adults

If you or your child are older than 6 months, do not panic. While early screening before myelination is complete is ideal, older children and adults can still be accurately monitored. Doctors will use specific techniques, such as administering a contrast dye (gadolinium), to clearly visualize the melanin deposits and any changes in the brain over time [1]. You have not missed your only window for accurate care.

What the Scan Should Include

For a screening to be thorough, it must include both the brain and the entire spine [1]. Although most deposits are found in the brain, NCM can involve the leptomeninges (the thin membranes covering both the brain and the spinal cord) [2][4]. Asymptomatic deposits in the spinal cord would be missed if only the brain were imaged [4].

Common Locations for Deposits

When a neuroradiologist reviews the images, they pay close attention to specific “hot spots” where melanin is most likely to gather. These include:

  • The Amygdala: Located in the anterior temporal lobes of the brain [2].
  • The Cerebellum: The area at the back of the brain responsible for balance and coordination [3].
  • The Brainstem: The base of the brain that connects to the spinal cord [2][3].

Even if the patient is hitting every milestone and showing no symptoms, the goal of an early MRI is to establish a baseline [3]. Having a clear picture is vital for your long-term medical record and allows you and your care team to monitor for any future changes with confidence.

Common questions in this guide

Why is the 6-month window important for an infant's NCM screening MRI?
Before 6 months, a baby's brain hasn't fully developed myelin, a fatty coating around the nerves. This lack of myelin allows melanin deposits to show up clearly as bright white spots on an MRI. After 6 months, myelination creates a camouflage effect, making deposits harder to detect.
Is it too late to get an accurate MRI if my child is older than 6 months?
No, it is not too late. While screening before 6 months is preferred, older children and adults can still be accurately monitored. Doctors simply use specific techniques, such as administering a contrast dye, to clearly visualize the melanin deposits.
What areas of the body should be included in an NCM screening MRI?
A thorough screening must include both the brain and the entire spinal cord. Melanin deposits can involve the membranes covering the spinal cord, and these deposits would be completely missed if only the brain was imaged.
Where are melanin deposits usually found in the brain?
Neuroradiologists typically look for melanin deposits in specific hot spots. These most commonly include the amygdala, the cerebellum, and the brainstem.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Does the MRI order specifically include the brain and the entire spinal cord?
  2. 2.Is the neuroradiologist aware they should be looking for T1-shortening (bright spots) in the amygdala, cerebellum, and brainstem?
  3. 3.If we are scanning an older patient, will contrast dye be used to help identify melanin deposits despite myelination?
  4. 4.How will the results of this MRI change our long-term monitoring or treatment plan?

Questions For You

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References

References (4)
  1. 1

    Neurocutaneous melanosis with an intracranial cystic-solid meningeal melanoma in an adult: A case report and review of literature.

    Liu BC, Wang YB, Liu Z, et al.

    World journal of clinical cases 2022; (10(15)):5025-5035 doi:10.12998/wjcc.v10.i15.5025.

    PMID: 35801056
  2. 2

    Spectrum of Clinical, Neuroimaging, and Cerebrospinal Fluid Features of Adult Neurocutaneous Melanocytosis.

    Qian M, Ren H, Qu T, et al.

    European neurology 2018; (80(1-2)):1-6 doi:10.1159/000488687.

    PMID: 30007971
  3. 3

    Age related changes in brain MR appearance in the course of neurocutaneous melanosis.

    Bekiesińska-Figatowska M, Sawicka E, Żak K, Szczygielski O

    European journal of radiology 2016; (85(8)):1427-31.

    PMID: 27423683
  4. 4

    Spinal melanoma with optic neuropathy -rare manifestation of Neurocutaneous melanosis and PET-MRI findings.

    Baskar D, Vengalil S, Chakkera P, et al.

    eNeurologicalSci 2024; (35()):100504 doi:10.1016/j.ensci.2024.100504.

    PMID: 38803399

This page provides educational information about MRI screening for neurocutaneous melanocytosis. Always consult your neurologist or pediatrician to determine the appropriate timing and imaging protocols for your specific situation.

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