Table 1.

Correlation of immunological state in HIV and FDG uptake

Author	Journal	Study	Objective	Comment or significant finding
Sharko et al. 1996 [9]	Proc Natl Acad Sci USA	Preclinical- Rhesus monkeys	Determined if FDG was able to identify activated lymphoid tissue and reflect extent of infection.	Infected animals were distinguishable from uninfectedcontrols. There was widespread lymphoid activation which correlated to area of viral replication. Significant abdominopelvic lymph node activation occurred particularly in terminal stages of disease. Fewer tissues had high FDG uptake in terminal animals compared with midstage animals.
Wallace et al. 2002 [10]	Virology	Preclinical- Rhesus monkeys	Determined if FDG reflected extent of infection.	Within a few days of primary infection a distinct pattern of lymphoid tissue activation was noted. At this earlystage of infection the axillary,cervical and mediastinal lymph nodes were activated. Increased FDG uptake preceded fulminant viral replication.
Scharko et al. 2003 [11]	Lancet	Clinical	Translational study of preclinical findings.	Distinct pattern of lymph node activation was observed. Head and neck activation in the acute stage, a generalised peripheral lymph node activation in the midstage and involvement of (central) abdominal lymph nodes in the final stage.
Iyengar et al. 2003 [12]	Lancet	Clinical	Investigated the ability of PET to measure magnitude of lymph node activation in patient recently infected and compared it to uninfected patients who received killed influenza vaccines.	Lymph node activation was more localised after vaccination with killed influenza virus compared with infected patients. Lymph nodeactivation in early infection (>18 months since seroconversion) was much more in cervical and axillary nodes compared with inguinal and iliac groups. Patient with chronic long term infection (stable viral load) had smallnumbers of persistently active disease.
Hardy G et al. 2004 [13]	HIV Med	Clinical	Provided evidence of thymic reconstitution after HAART initiation.	A clear correlation between FDG uptake in thymus and increase in number of CD4 cells. When there was no thymic uptake therewas no increase in peripheral CD4 cell count.
Brust et al. 2006. [14]	AIDS	Clinical	Evaluated biodistribution visually and quantitatively in both uninfected and infected patients. Infected patients were at different stages of disease and different states of viral suppression by HAART.	Uninfected and healthy infected patients with suppressed viral loads had little or no FDG nodal uptake. Vireamic patients on the contrary with early or advanced infection had increased FDG uptake in peripheral nodes. The biodistribution was similar for early and advanced–stage disease. Patients who discontinued HAART had negative baseline scans but developed nodal uptake and increase inviralloadaftertherapycessation. Splenic uptake was higher in actively replicating vireamic patients.
Liu et al. 2009	Nucl Med Commun	Clinical	Evaluated the clinical significance of increased splenic uptake of FDG.	Splenic uptake is significantly greater than liver uptake in the actively replicating vireamic group.
Lucignani et al. 2009 [15]	Eur J Nucl Med Mol Imaging	Clinical	Determined whether infected patients can be differentiated on the basis of sites of viral replication and whether findings can be related to immunological variables and AIDS history status.	PET demonstrated different patterns of uptake. All infected patients who were on HAART showed normal FDG uptake whether they had suppressed or high viral load. In HAART-naive infected patients with high vireamia the scan showed multiple foci of increased FDG uptake in lymph nodes. FDG nodal uptake in the upper torso particularly the axillary correlated to vireamia levels when below 100,000 copies/ml. In the HAART-naive group with viral load greater than 100,000 copies/ml, FDG uptake was observed in the inguinal nodes.
Sathekge et al. 2010 [16]	Nucl Med Commun	Clinical	Determined distribution of nodal uptake and correlated uptake with immunological and virological factors in patients on HAART.	Predominant sites of lymph node involvement were the cervical and axillary regions, followed by the inguinal region. CD4 count was inversely correlated to the average SUV of the lymph nodes. The viral load was positively correlated with the averaged SUV of the involved lymph nodes.
Transkovic et al. 2011 [17]	AIDS	Clinical	Determined the correlation between thymic uptake and recovery of CD4.	Thymic tissue did not show any uptake in patients with poor recovery of CD4 after initiation of HAART.
Lilievere et al. 2012 [18]	J Acquire immune Defic Syndr	Clinical	Evaluated thymic activity with FDG uptake and precursors for thymic activity.	Thymic uptake was lower in HAART-treated patients compared with age-matched controls. Metabolic thymic activity correlated with indirect molecular and phenotypic markers of thymic output