Mapping COVID-19 with nuclear imaging: from infection to functional sequelae.

The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, or coronavirus disease 2019, COVID-19) has been raging all over the globe for more than one year. COVID-19 virus can attack multiple organs through binding to angiotensin-converting enzyme 2 (ACE2) receptors and further induce systemic inflammation and immune dysregulation. In the last issue of 2020 AJNMMI (http://www.ajnmmi.us), Lima summarized current biological complications of COVID-19, their underlying mechanisms, and our options of mapping these functional sequelae using nuclear imaging techniques. Four major organs, including the lung, heart, kidney, and endothelium, were identified as most vulnerable to COVID-19 viruses in severe patients. Nuclear medicine proved accurate and sensitive in assessing the onset, progression, and treatment of COVID-19 patients. By choosing the most appropriate radiotracers and imaging methods, clinicians and researchers are able to analyze and monitor the presence of inflammation, fibrosis, and changes of metabolic rates in organs of interest. With these desirable nuclear imaging methods, systematic evaluation of COVID-19, from its onset to functional sequela, can be achieved with rational patient stratification and timely treatment monitoring, which we believe will eventually lead to full victory against the pandemic.