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Use of quantitative susceptibility mapping (QSM) in progressive multifocal leukoencephalopathy
C Carra-Dalliere1, N Menjot de Champfleur2, J Deverdun2
1Department of Neurology, Montpellier University Hospital, Gui-de-Chauliac Hospital, 34295 Montpellier, France.
Background:
Progressive multifocal leukoencephalopathy (PML) is an opportunistic demyelinating encephalopathy related to JC virus. Its characteristics on conventional brain MRI are well known and are important for the diagnosis.
Objective:
To analyze SWI hypointensities recently described in U-fibers and cortex adjacent to the white matter lesions of PML.
Methods:
Prospective study including four patients with an history of definite diagnosis of PML. Clinical data were collected retrospectively. Brain MRI exams were done on a 3T magnet, including FLAIR, T2 GRE sequences and SWI.
Results:
Four males were included (mean age: 47 years, mean PML duration: 24.2 months). Immunosuppression was related to AIDS (n=2), natalizumab for multiple sclerosis (n=1), B-cell lymphoma treated by chemotherapeutic agents and rituximab (n=1). All patients had SWI hypointensities in cortex and/or U-fibers adjacent to the white matter lesions. QSM always suggested a paramagnetic effect.
Conclusion:
SWI and T2 GRE hypointensities in cortex and U-fibers adjacent to the white matter lesions seem highly prevalent in PML, irrespective of the delay between PML onset and the MRI. QSM data suggest a paramagnetic effect.
Insights
SWI hypointensities in the cortex and U-fibers are common in progressive multifocal leukoencephalopathy (PML), an opportunistic brain infection. These findings, visible on MRI, suggest a paramagnetic effect and aid in PML diagnosis.
Area of Science:
- Neuroimaging
- Neurology
- Infectious Diseases
Background:
- Progressive multifocal leukoencephalopathy (PML) is a severe opportunistic demyelinating disease caused by the JC virus.
- Conventional MRI findings for PML are established and crucial for diagnosis.
Purpose of the Study:
- To investigate the presence and characteristics of SWI (susceptibility-weighted imaging) hypointensities in the U-fibers and cortex adjacent to PML white matter lesions.
- To analyze the potential paramagnetic effect indicated by Quantitative Susceptibility Mapping (QSM).
Main Methods:
- Prospective study of four patients with a confirmed PML diagnosis.
- Retrospective collection of clinical data.
- Brain MRI performed on a 3T magnet, including FLAIR, T2 GRE, and SWI sequences.
Main Results:
- All four male patients (mean age 47) exhibited SWI hypointensities in the cortex and/or U-fibers near PML lesions.
- Underlying causes of immunosuppression included AIDS, natalizumab for multiple sclerosis, and chemotherapy/rituximab for lymphoma.
- QSM analysis consistently indicated a paramagnetic effect associated with these hypointensities.
Conclusions:
- SWI and T2 GRE hypointensities in the cortex and U-fibers adjacent to PML lesions are highly prevalent.
- These findings appear irrespective of the time elapsed since PML onset.
- QSM data suggest a paramagnetic origin for these observed hypointensities.
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