Purpose <p>[<sup>18</sup>F]DPA-714 is a valuable tracer for studying (neuro)inflammation, with well-characterized tracer kinetics and an established imaging window. However, its clinical utility is restricted by the TSPO polymorphism (rs6971), which influences binding affinity in humans. The newly developed tracer [<sup>18</sup>F]DPA-814 overcomes this limitation and has shown promising results in a preclinical rat model. To further assess its clinical potential, we compared [<sup>18</sup>F]DPA-814 to [<sup>18</sup>F]DPA-714 for inflammation imaging in SARS-CoV-2-infected macaques in a longitudinal setting.</p> Procedures <p>Dynamic positron emission tomography (PET) imaging was conducted in four healthy macaques to identify the optimal imaging window for [<sup>18</sup>F]DPA-814. Four additional macaques were infected with SARS-CoV-2 and monitored for 12 months using whole-body PET-computed tomography (CT) with both tracers. Baseline scans were compared to PET-CTs obtained at 4, 9 and 16 days and at 6 and 12 months post-infection, covering the head, thorax and abdomen. Tracer uptake was assessed in several organs.</p> Results <p>At baseline, [<sup>18</sup>F]DPA-814 showed higher lung uptake with minimal washout compared to [<sup>18</sup>F]DPA-714. Although lung lesions developed after infection, [<sup>18</sup>F]DPA-814 did not demonstrate lesion-specific uptake, unlike [<sup>18</sup>F]DPA-714. In the brain, the tracers also displayed divergent uptake patterns despite comparable TSPO levels across animals and regions.</p> Conclusions <p>[<sup>18</sup>F]DPA-814 exhibits a distinct whole-body distribution, particularly in the lungs and brain, in both naïve and SARS-CoV-2-infected macaques compared with [<sup>18</sup>F]DPA-714, likely reflecting differences in tracer kinetics. Based on these data, [<sup>18</sup>F]DPA-814 may not fully replace [<sup>18</sup>F]DPA-714 for lung and brain imaging, and further studies are required to evaluate its suitability in other anatomical regions.</p>

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Comparison of [18F]DPA-814 with [18F]DPA-714 for TSPO Imaging in an Experimental Model

  • J. van der Bie,
  • J. Bakker,
  • E. J. Verschoor,
  • E. Nutma,
  • J. Middeldorp,
  • W. Beaino,
  • M. Kassiou,
  • J. J. Danon,
  • J. A. M. Langermans,
  • A. D. Windhorst,
  • M. A. Stammes

摘要

Purpose

[18F]DPA-714 is a valuable tracer for studying (neuro)inflammation, with well-characterized tracer kinetics and an established imaging window. However, its clinical utility is restricted by the TSPO polymorphism (rs6971), which influences binding affinity in humans. The newly developed tracer [18F]DPA-814 overcomes this limitation and has shown promising results in a preclinical rat model. To further assess its clinical potential, we compared [18F]DPA-814 to [18F]DPA-714 for inflammation imaging in SARS-CoV-2-infected macaques in a longitudinal setting.

Procedures

Dynamic positron emission tomography (PET) imaging was conducted in four healthy macaques to identify the optimal imaging window for [18F]DPA-814. Four additional macaques were infected with SARS-CoV-2 and monitored for 12 months using whole-body PET-computed tomography (CT) with both tracers. Baseline scans were compared to PET-CTs obtained at 4, 9 and 16 days and at 6 and 12 months post-infection, covering the head, thorax and abdomen. Tracer uptake was assessed in several organs.

Results

At baseline, [18F]DPA-814 showed higher lung uptake with minimal washout compared to [18F]DPA-714. Although lung lesions developed after infection, [18F]DPA-814 did not demonstrate lesion-specific uptake, unlike [18F]DPA-714. In the brain, the tracers also displayed divergent uptake patterns despite comparable TSPO levels across animals and regions.

Conclusions

[18F]DPA-814 exhibits a distinct whole-body distribution, particularly in the lungs and brain, in both naïve and SARS-CoV-2-infected macaques compared with [18F]DPA-714, likely reflecting differences in tracer kinetics. Based on these data, [18F]DPA-814 may not fully replace [18F]DPA-714 for lung and brain imaging, and further studies are required to evaluate its suitability in other anatomical regions.