Basic Science of PET Imaging for Inflammatory Diseases

Abstract

FDG-PET/CT has recently emerged as a useful tool for the evaluation of inflammatory diseases too, in addition to that of malignant diseases. The imaging is based on active glucose utilization by inflammatory tissue. Autoradiography studies have demonstrated high FDG uptake in macrophages, granulocytes, fibroblasts, and granulation tissue. Especially, activated macrophages are responsible for the elevated FDG uptake in some types of inflammation. According to one study, after activation by lipopolysaccharide of cultured macrophages, the [ 14 C]2DG uptake by the cells doubled, reaching the level seen in glioblastoma cells. In activated macrophages, increase in the expression of total GLUT1 and redistributions from the intracellular compartments toward the cell surface have been reported. In one rheumatoid arthritis model, following stimulation by hypoxia or TNF-α, the highest elevation of the [ 3 H]FDG uptake was observed in the fibroblasts, followed by that in macrophages and neutrophils. As the fundamental mechanism of elevated glucose uptake in both cancer cells and inflammatory cells, activation of glucose metabolism as an adaptive response to a hypoxic environment has been reported, with transcription factor HIF-1α playing a key role. Inflammatory cells and cancer cells seem to share the same molecular mechanism of elevated glucose metabolism, lending support to the notion of usefulness of FDGPET/CT for the evaluation of inflammatory diseases, besides cancer.

FDG-PET/CT images of COVID-19: a comprehensive review

“…FDG-PET/CT has utility in the staging, restaging, and assessment of therapeutic effects in malignancy, and is used in the management of patients with malignancy (17). Because FDG accumulates in activated inflammatory cells including neutrophils and macrophages, FDG-PET/ CT has huge potential for diagnosing and monitoring inflammatory disease (18).…”

“…However, various diseases can mimic these features, including other viral pneumonias (7), and chest CT is therefore not currently recommended as an initial screening tool (8). Following numerous reports regarding the CT appearance of COVID-19, several groups have reported [ 18 F]-2-fluoro-2-deoxy-D-glucose (FDG)positron emission tomography/computed tomography (PET/CT) imaging findings of COVID-19 (9)(10)(11)(12)(13)(14)(15)(16). We experienced two measurements of FDG-PET/CT in a COVID-19 infected patient, one was 4 weeks from symptoms onset and the other was 4 weeks after the first FDG-PET/CT scan (Figure 2).…”

Route of Francisella tularensis infection informs spatiotemporal metabolic reprogramming and inflammation in mice

“…The distinct spatiotemporal patterns in cytokine production between intradermal and intranasal infection implicate potential differences in the propensity to increase glycolysis after FTT infection. Measuring distribution and uptake of glucose derivatives with preclinical imaging techniques can identify tissues where increased glycolysis is actively supporting inflammatory functions [ 19 , 20 ]. Therefore, we next assessed the tissue distribution of the glucose derivative XenoLight RediJect 2-DG 750 (RJ2-DG-750) using optical fluorescence imaging in mice following i.n.…”

Candidate Tracers for Imaging Colony-Stimulating Factor 1 Receptor in Neuroinflammation with Positron Emission Tomography: Issues and Progress

“…Several articles have earlier summarized reported candidate CSF1R PET tracers, but only briefly. ,− A growing number of candidate PET tracers for imaging brain CSF1R are now being reported (Table ). In this Review, we discuss and compare the performances of all candidate CSF1R PET tracers reported to date and their issues.…”