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

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