Imaging of inflammatory processes in osteoarthritis (OA) disease models using a novel ¹¹¹In-labeled folate SPECT conjugate for determining macrophage activity in rats, opens new possibilities for targeted monitoring and therapy in OA patients. 

Previous challenges of such imaging studies included low expression of the folate receptors and accumulation of radioconjugates mainly in the renal tissue. In the present study, however, the newly designed conjugate, comprising an albumin-binding entity, resulted in a significant decrease of the renal uptake as observed by SPECT/CT images, acquired with the high-resolution, high-sensitivity VECTor4CT system (Figure 1).

In addition, the authors demonstrated that macrophage activity, responsible for the presence of inflammation in OA, was significantly increased and higher than in the control groups, highlighting the possibility to quantitatively assess even low levels of such processes (Figure 2). Therefore, the use of ¹¹¹In-folate suggests a promising tool for in vivo imaging and quantification of inflammation in animal models of OA.