The remarkable growth of nuclear medicine in the past 20 years is attributable to a number of factors, including the clinical recognition that imaging with [F]FDG, touted as the ‘‘molecule of the millennium’’ [1], improves diagnosis and staging, especially when it is used with devices that provide anatomic reference for the metabolic images. Furthermore, the growth of FDG PET/CT has been paralleled by an evolution of other applications of ‘‘molecular imaging’’ for both diagnostic and therapeutic purposes [1]. This issue of Clinical and Translational Imaging focuses on the imaging of multiple parameters (achieved either by imaging with multiple agents or by imaging at multiple time points) as a means of better characterizing the presence or severity of a disorder. In the opening article, Ciarmiello et al. [2] provide a comprehensive review of the complex pathophysiology of degenerative brain disorders. In this regard, both PET and SPECT imaging use a wide range of tracers to track pathophysiological processes in the healthy and diseased brain, especially for the purpose of investigating the pathophysiological aspects of neurodegenerative disorders. This area of investigation is extremely important considering the aging of the global population and the high prevalence of brain disorders, such as Alzheimer’s disease and Parkinson’s disease, in elderly persons. Utilizing molecular imaging in routine clinical practice may overcome the limitations of a diagnostic approach based solely on clinical judgment and structural imaging. These molecular imaging techniques will foster the development of new drugs whose effects on specific pathways can be monitored, and compared to clinical outcomes. Strauss and Fox explore new techniques that expand the applications of approved radiopharmaceuticals in patients with heart failure and atherosclerosis [3]. Their article focuses mainly on the evaluation of mitochondrial function and sympathetic innervation in patients with heart failure. The new applications they discuss, by providing functional information with high predictive value, allow identification of heart failure patients at high risk of clinical events. Another area of growing interest is linked to the possibility of directly imaging and evaluating focal vascular inflammation, microcalcification and calcification in patients with dyslipidemia. Imaging-based characterization of inflammation, or early phases of calcification in atheromas, is expected to stimulate the development of therapeutic strategies that are more personalized than those based on traditional measurements of lipid levels in patients with dyslipidemia. Characterization of atheromas, especially in the coronary and carotid arteries, may be the imaging approach of choice to permit effective pharmacologic therapy geared at reducing the incidence and severity of clinical events. Palestro et al. [4] discuss the current role of molecular imaging with single-photon and positron-emitting tracers in the evaluation of inflammation and infection. After reviewing the clinical role of well-established imaging procedures based on approved radiopharmaceuticals (chiefly, labeled autologous leukocytes and [F]FDG, even though there is still a role for Ga-citrate scintigraphy), the authors describe ongoing investigations of tracers, such as radiolabeled antibiotics—these were originally expected to be ‘‘infection-specific’’ imaging agents, but to G. Mariani (&) Regional Center of Nuclear Medicine, University of Pisa, Via Roma 67, 56126 Pisa, Italy e-mail: giuliano.mariani@med.unipi.it