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Difficulty: Very hardInterpreting Imaging Results

Match the following pathognomonic central nervous system magnetic resonance imaging (MRI) findings with their most likely corresponding underlying neurodegenerative or metabolic condition.

  • Cruciform hyperintense signal within the pons on axial T2-weighted MRIMultiple system atrophy, cerebellar type (MSA-C)
  • Severe atrophy of the midbrain tegmentum with a relatively preserved pons on midsagittal T1-weighted MRIProgressive supranuclear palsy (PSP)
  • Bilateral symmetric hyperintensity in the pulvinar thalamic nuclei on FLAIR MRIVariant Creutzfeldt-Jakob disease (vCJD)
  • Central hyperintensity surrounded by symmetric hypointensity in the globus pallidus on T2-weighted MRIPantothenate kinase-associated neurodegeneration (PKAN)

Answer

Cruciform pons hyperintensity matches MSA-C; midbrain tegmentum atrophy matches PSP; pulvinar hyperintensity matches vCJD; and target-like globus pallidus signal matches PKAN.
Each pathognomonic imaging sign directly reflects the underlying selective neuronal vulnerability, distinct protein deposition, or specific tract degeneration unique to these rare neurodegenerative and metabolic conditions.

Step-by-Step Solution

1
Analyze the axial T2-weighted pontine finding.
Identify the cruciform hyperintensity as the 'hot cross bun' sign.
This specific presentation indicates neurodegeneration of the pontocerebellar tracts, which uniquely points to MSA-C.
2
Evaluate the midsagittal T1-weighted midbrain finding.
Identify midbrain tegmental atrophy as the 'hummingbird' sign.
This is essential for differentiating PSP from Parkinson disease and other parkinsonian syndromes that do not exhibit severe midbrain volume loss.
3
Assess the FLAIR thalamic finding.
Recognize the posterior thalamic hyperintensity as the 'pulvinar' sign.
This is a classic radiologic hallmark required for the clinical diagnosis of variant CJD.
4
Interpret the T2-weighted globus pallidus finding.
Identify the central hyperintensity with surrounding hypointensity as the 'eye of the tiger' sign.
This reflects distinct iron deposition patterns and central gliosis characteristic of PKAN.

Key Concept

Pathognomonic neuroimaging signs in atypical parkinsonian and neurodegenerative disorders.
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Interpreting Imaging Results

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