Progressive Multifocal Leukoencephalopathy: Serial High-b-Value Diffusion-Weighted MR Imaging and Apparent Diffusion Coefficient Measurements to Assess Response to Highly Active Antiretroviral Therapy
S.I. Usiskina,
A. Bainbridgec,
R.F. Millerb and
H.R. Jägera,d,e
a Department of Imaging, University College London Hospital
b Centre for Sexual Health and HIV Research, Department of Population Sciences and Primary Care, Royal Free and University College Medical School, University College London
c Department of Medical Physics, University College London Hospital, London
d The Institute of Neurology, University College London, London
e Lysholm Department of Neuroradiology, The National Hospital for Neurology and Neurosurgery, London, England
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Fig 1. Pretreatment MR imaging study.
A, Trace image of DWI1000 shows a lesion in the left MCP, which is hyperintense anteriorly and posteriorly and of intermediate signal intensity centrally. The rounded ring-shaped markings indicate where the regions of interest have been placed on the corresponding ADC maps.
B, Trace image of DWI3000 shows a hypointense lesion center and a peripheral high-signal-intensity rim, which is much more clearly defined than on the trace images of DWI1000 (Fig 1A).
C, Anisotropic image DWI3000, sensitive to water movement in the section (supero-inferior) direction, shows high signal intensity in the right MCP, which is a normal finding because the MCP represents a barrier to free water movement in this direction. The PML lesion in the mid and posterior portions of the left MCP appears no longer hyperintense, implying a loss of structural integrity. Note also that water diffusion is not impeded by the superior cerebellar peduncles, which run in a craniocaudal direction.
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Fig 2. MR imaging study 4 weeks after commencing HAART.
A, Trace images of DWI3000 no longer show any high-signal-intensity rim at the periphery of the lesion, and the left MCP appears only slightly less bright than the right one.
B, On the anisotropic images of DWI3000, sensitive for water movement in the section (supero-inferior) direction, the left MCP appears now nearly as bright as the right MCP, implying that structural integrity has been regained.
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