A role for susceptibility weighted imaging in progressive multifocal leukoencephalopathy

Area of Science:

• Radiology
• Neuroimaging
• Neurology

Background:

• Progressive multifocal leukoencephalopathy (PML) is a rare, serious demyelinating disease of the central nervous system.
• Accurate and timely diagnosis of PML is crucial for patient management and prognosis.
• Conventional MRI sequences can sometimes present indeterminate findings in PML.

Observation:

• Two cases of PML were analyzed using magnetic resonance imaging (MRI).
• A specific radiologic finding was observed: hypointense signal of subcortical U-fibers.
• This finding was noted on susceptibility-weighted (SW) sequences.

Findings:

• The hypointense signal on SWI sequences in subcortical U-fibers is a potential new imaging biomarker for PML.
• Iron deposition is hypothesized as the underlying cause for this observed signal.
• The finding was present in a patient treated with chemotherapy (rituximab) for non-Hodgkin's lymphoma and in an HIV-infected patient.

Implications:

• Susceptibility-weighted imaging (SWI) may enhance diagnostic accuracy for PML.
• This technique could be particularly valuable in differentiating PML from other conditions with similar imaging features.
• Reducing the likelihood of missed PML diagnoses can lead to earlier intervention and potentially improved outcomes.