High b-value diffusion-weighted imaging in progressive multifocal leukoencephalopathy in HIV patients.
OBJECTIVE
An ill-defined hyperintense edge and hypointense core on diffusion-weighted imaging (DWI) is typical of progressive multifocal leukoencephalopathy (PML). We aimed to investigate whether a b-value of 3,000 s/mm2(b3000) can improve visualisation of PML, or provide different structural information compared to 1,000 s/mm2(b1000).


METHODS
We retrospectively identified HIV-positive patients with confirmed PML studied under a clinical protocol including both b1000 and b3000 DWI. The rim and core of each PML lesion and normal-appearing white matter (NAWM) were outlined on trace-weighted DWI. Signal intensities, apparent diffusion coefficient (ADC) values and volumes were measured and compared between b1000 and b3000.


RESULTS
Nine lesions from seven patients were analysed. The rim and core were better visualised on b3000, with higher signal of the rim and lower signal of the core compared to NAWM. The hyperintense rim had non-restricted average ADCs, but included foci of low ADC on both b3000 and b1000. Despite similar total lesion volumes, b3000 displayed significantly larger core and smaller rim volumes than b1000.


CONCLUSIONS
b3000 improves visualisation of this important PML hallmark. Moreover, b3000 partly reclassifies tissue from rim into core, and might provide potentially more accurate biomarkers of PML activity and prognosis.


CONCLUSIONS
• B3000 improves contrast resolution between lesion rim, core and normal-appearing white matter. • B3000 improves identification of the typical rim-and-core pattern of PML lesions. • B3000 and b1000 similarly identify lesions, but b3000 results in smaller rims and larger cores. • B3000 excludes some high diffusion components from rim, reclassifying them into core. • B3000 DWI may provide more precise PML biomarkers of disease activity and tissue damage.
Neuroradiology Department, San Raffaele Scientific Institute, Milan, Italy.|Lysholm Department of Neuroradiology, The National Hospital for Neurology and Neurosurgery, Queen Square, London, UK.|Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, Queen Square, London, UK.
Claudia
C
Godi
Lysholm Department of Neuroradiology, The National Hospital for Neurology and Neurosurgery, Queen Square, London, UK.|Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, Queen Square, London, UK.
Enrico
E
De Vita
Vita-Salute San Raffaele University, Milan, Italy.
Enrico
E
Tombetti
Lysholm Department of Neuroradiology, The National Hospital for Neurology and Neurosurgery, Queen Square, London, UK.|Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, Queen Square, London, UK.
Indran
I
Davagnanam
Centre for Sexual Health and HIV Research, Research Department of Infection and Population Health, University College London, London, UK.
Lewis
L
Haddow
Lysholm Department of Neuroradiology, The National Hospital for Neurology and Neurosurgery, Queen Square, London, UK. r.jager@ucl.ac.uk.|Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, Queen Square, London, UK. r.jager@ucl.ac.uk.|Centre of Medical Imaging, University College Hospital, London, UK. r.jager@ucl.ac.uk.
Hans Rolf
HR
Jäger
D017088:AIDS-Related Opportunistic Infections / Q000000981:diagnostic imaging* / Q000473:pathology; D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D018450:Disease Progression; D005260:Female; D006801:Humans; D007968:Leukoencephalopathy, Progressive Multifocal / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D055815:Young Adult
Diffusion MRI; Diffusion magnetic resonance imaging; Diffusion-weighted MRI; Human immunodeficiency virus; Progressive multifocal leukoencephalopathy