Whole body positron emission tomography imaging of simian immunodeficiency virus-infected rhesus macaques.

Abstract

Pathogenesis of simian immunodeficiency virus (SIV) infection in rhesus macaques begins with acute viremia and then progresses to a distributed infection in the solid lymphoid tissues, which is followed by a process of cellular destruction leading to terminal disease and death. Blood and tissue specimens show the progress of infection at the cellular level but do not reveal the pattern of infection and host responses occurring throughout the body. The purpose of this investigation was to determine whether positron emission tomography (PET) imaging with intravenous 2-18F-2-deoxyglucose (FDG) could identify activated lymphoid tissues in a living animal and whether this pattern would reflect the extent of SIV infection. PET images from SIV-infected animals were distinguishable from uninfected controls and revealed a pattern consistent with widespread lymphoid tissue activation. Significant FDG accumulation in colon along with mesenteric and ileocaecal lymph nodes was found in SIV infection, especially during terminal disease stages. Areas of elevated FDG uptake in the PET images were correlated with productive SIV infection using in situ hybridization as a test for virus replication. PET-FDG images of SIV-infected animals correlated sites of virus replication with high FDG accumulation. These data show that the method can be used to evaluate the distribution and activity of infected tissues in a living animal without biopsy. Fewer tissues had high FDG uptake in terminal animals than midstage animals, and both were clearly distinguishable from uninfected animal scans.

An attenuated Lassa vaccine in SIV-infected rhesus macaques does not persist or cause arenavirus disease but does elicit Lassa virus-specific immunity

“…Upon necropsy it was evident they also had swollen ileo-caecal lymph nodes that are a hallmark of terminal AIDS [33]. Five of the original 16 SIV-infected monkeys died of AIDS prior to the onset of the ML29 vaccinations, and the time to death of the 11 remaining monkeys was not detectably influenced by the ML29 vaccination.…”

Early Effects of Irradiation on [123I]-IMT and [18F]-FDG Uptake in Rat C6 Glioma Cells

“…It is well known, that high-dose irradiation induces an attraction and activation of inflammatory cells for up to 6 months after radiotherapy [46]. Inflammatory cells like macrophages, lymphocytes and leukocytes lead to a prominent increase in [ 18 F]-FDG uptake comparable to that of tumor cells [17,22,30,53,57,66]. Therefore, there is no clear-cut difference between the metabolic needs of inflammatory areas and Hautzel & Müller-Gärtner performed [ 18 F]-FDG PET scans in combination with an antigranulocyte antibody scintigraphy to differentiate between enhanced glucose metabolism post irradiation caused by the tumor and by additional inflammatory reactions [18].…”

Clinical significance of diffusely increased splenic uptake on FDG-PET

“…lymphoma or sarcoma), FDG-PET/CT is also used for evaluation of the anatomical sites of viral replication or nodal activation during the course of HIV infection, which are associated with clinical stages and also critical to the rational design of therapies for controlling and preventing the disease [26][27][28]. Iyengar et al [29] first described that there was increased splenic uptake compared with hepatic uptake in the early stage of HIV infection.…”