Structural and functional imaging in parkinsonian syndromes

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Parkinsonian disorders are common and challenging to diagnose due to overlapping symptoms.
• Imaging plays an increasingly vital role in diagnosing and managing parkinsonism.
• Familiarity with imaging patterns is crucial for radiologists.

Purpose of the Study:

• To review common magnetic resonance (MR) and molecular imaging patterns for idiopathic Parkinson disease and atypical parkinsonian syndromes.
• To discuss the interpretation of molecular imaging studies for parkinsonism diagnosis.
• To highlight the role of multimodality imaging in diagnosis, therapy selection, and prognosis.

Main Methods:

• Review of magnetic resonance (MR) imaging patterns.
• Interpretation of molecular imaging studies: FDG PET for cerebral metabolism, amyloid PET (using C-11 Pittsburgh compound B and F-18 florbetapir) for amyloid deposition, and I-123 ioflupane SPECT for dopaminergic activity.
• Correlation of imaging findings with clinical evaluation.

Main Results:

• No single imaging test is diagnostic; a combination of tests aids differential diagnosis.
• I-123 ioflupane SPECT confirms dopaminergic neuron loss, distinguishing parkinsonism from essential tremor and drug-induced parkinsonism.
• FDG PET shows specific patterns of neuronal dysfunction for different parkinsonian syndromes.
• MR imaging findings are often nonspecific, but T2 signal changes can suggest multiple system atrophy or progressive supranuclear palsy.
• Amyloid-binding PET can support a diagnosis of dementia with Lewy bodies.

Conclusions:

• Multimodality imaging, combined with clinical evaluation, enables accurate diagnosis of parkinsonian syndromes.
• Imaging information assists in selecting appropriate therapies and provides prognostic insights.
• Radiologists' understanding of these imaging patterns is essential for effective patient management.