Fluorodeoxyglucose imaging in healthy subjects with HIV infection: impact of disease stage and therapy on pattern of nodal activation

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Nodal uptake in areas of lymphocyte activation can be visualized using fluorodeoxyglucose. Various patterns of fluorodeoxyglucose accumulation in HIV-positive patients have been described previously and hypothesized potentially to represent regions of active HIV replication or nodal activation. We evaluated the utility of fluorodeoxyglucose scanning as a tool to study HIV pathogenesis. We evaluated fluorodeoxyglucose biodistribution visually and quantitatively in HIV-negative individuals and various groups of HIV-infected patients to determine the impact on the pattern of nodal activation of HIV infection, the stage of HIV infection and degree of viremia, and HAART. In addition, we attempted to image anatomical site(s) of ongoing HIV replication in patients with suppressed HIV viremia on HAART, but subsequently discontinued HAART. We performed fluorodeoxyglucose imaging on five groups: HIV-negative, HIV-positive individuals with early infection, HIV-positive patients with advanced disease, HIV-positive patients with suppressed viral loads, and HIV-positive patients who stopped HAART. Healthy HIV patients with suppressed viral loads and HIV-negative individuals had no or little fluorodeoxyglucose nodal accumulation or any other hypermetabolic areas, whereas viremic individuals with early and advanced HIV had increased fluorodeoxyglucose in the peripheral nodes, indicating that fluorodeoxyglucose potentially identifies areas of HIV replication. Fluorodeoxyglucose biodistribution was similar between early and advanced-stage disease. Four of five patients taken off HAART had negative baseline scans but developed nodal uptake and increases in viral loads. Abnormal fluorodeoxyglucose accumulation occurs in the nodes of individuals with detectable viral loads. Interruption of effective HAART results in the activation of previously quiescent nodal areas.