PML in HIV 1 Running head : Diffusion imaging of PML in HIV Neuropsychological and neuroimaging outcome of HIV-associated progressive multifocal leukoencephalopathy in the era of ART : a case report

In the present case report we describe the functional outcome of a patient with human immunodeficiency virus (HIV) and progressive multifocal leukoencephalopathy (PML) on treatment with antiretroviral therapy. Neuropsychological tests and structural magnetic resonance imaging were obtained at baseline and again after 12 months to define the severity of white matter damage associated with PML. Diffusion tensor imaging (DTI) was also obtained at the second evaluation to visualize the neuronal damage in the subcortical white matter using region-based analyses and novel scalar metrics based on streamtube tractography. Neuropsychological and neuroimaging data obtained at the 12-month evaluation were compared to an HIV-infected patient without PML and with good immune system health, and to a second HIV-infected patient without PML but with notable immunosuppression. Review of the HIV/PML patient’s cognitive data at both time points revealed significant impairments in domains purportedly subserved by subcortical networks compared to the two control subjects, and a reference group of healthy seronegative controls. Similarly, the HIV/PML patient’s white matter lesion load and whole brain volume were markedly different from the control subjects at both time points. The tractography-defined scalar metrics suggest significant white matter fiber loss associated with HIV/PML that was not evident in either HIV control patient. Our findings suggest that PML is associated with marked cognitive and neuroimaging abnormalities in the context of ART. In addition DTI provides an opportunity to visualize and quantify the degree of white matter damage beyond the capacity of traditional structural imaging.