New horizons in nuclear cardiology: Imaging of peripheral arterial disease

Lower extremity peripheral artery disease (PAD) is characterized by impairment of blood flow associated with arterial stenosis and frequently coexisting microvascular disease and is associated with high rates of morbidity and mortality. Current diagnostic modalities have limited accuracy in early diagnosis, risk stratification, preprocedural assessment, and evaluation of therapy and are focused on the detection of obstructive atherosclerotic disease. Early diagnosis and assessment of both large vessels and microcirculation may improve risk stratification and guide therapeutic interventions. Single-photon emission computed tomography and positron emission tomography imaging have been shown to be accurate to detect changes in perfusion in preclinical models and clinical disease, and have the potential to overcome limitations of existing diagnostic modalities, while offering novel information about perfusion, metabolic, and molecular processes. This review provides a comprehensive reassessment of radiotracer-based imaging of PAD in preclinical and clinical studies, emphasizing the challenges that arise due to the complex physiology in the peripheral vasculature. We will also highlight the latest advancements, underscoring emerging artificial intelligence and big data analysis, as well as clinically relevant areas where the field could advance in the next decade.