Cu-DOTATATE Positron Emission Tomography (PET) of Infection: Imaging of Macrophages in Experimental Model of Lyme Arthritis.

Macrophages play a key role in the inflammatory response in Lyme arthritis (LA) and could be a target for diagnosing and monitoring active sensu lato () infection. Therefore, we evaluated the potential of macrophage imaging using Cu-DOTATATE PET/CT for detection of activity in a murine model of LA. LA was established in C3H/HeNRj mice infected with B31 strain ML23 pBBE22. Bioluminescence imaging was performed to detect migration of spirochetes and inflammatory phagocytes to the joints. Three weeks post-infection Cu-DOTATATE PET/CT imaging was performed at an early (3 h) and late (48 h) time point. Plasma levels of a systemic macrophage marker in plasma CD163 were measured. Cu-DOTATATE uptake in infected joints was increased at the early ( < 0.0001) and late time points ( = 0.0005) compared with uptake in non-infected controls. No significant difference in plasma levels of CD163 was measured. Cu-DOTATATE PET allows for in vivo detection and quantification of LA locally in the joints through non-invasive visualization of macrophages. In contrast, measurement of a systemic macrophage marker in plasma, CD163, did not allow to detect disease. We suggest that Cu-DOTATATE PET could become a valuable diagnostic tool for in situ detection of infection-related inflammation.