Antibody-based tracers for PET/SPECT imaging of chronic inflammatory diseases.

Chronic inflammatory diseases are often progressive, resulting not only in physical damage to patients but also social and economic burdens, making early diagnosis of them very critical. Nuclear medicine techniques can enhance the detection of inflammation by providing functional as well as anatomical information when combined with other modalities such as magnetic resonance imaging, computed tomography or ultrasonography. While small molecules and peptides were mainly used for the treatment and imaging of chronic inflammatory diseases in the past, antibodies and their fragments have also been emerging for chronic inflammatory diseases since they show high specificity to their targets and can have various biological half-lives depending on how they are engineered. In addition, imaging using antibodies or their fragments can visualize the in vivo biodistribution of the probes or help monitor therapeutic responses, providing physicians a greater understanding of drug behavior in vivo and another means of monitoring their patients. In this review, we introduce various targets and radiolabeled antibody-based probes for molecular imaging of chronic inflammatory diseases in preclinical and clinical studies. Targets can be classified into three different categories: 1) cell adhesion molecules, 2) surface markers on immune cells, and 3) cytokines or enzymes, and limitations and future directions of using radiolabeled antibodies for imaging inflammatory diseases are also discussed.