oa Editorial [Hot topic: Seeing is Believing: Molecular Imaging in Living Subjects (Guest Editor: Weibo Cai)]

Over the last decade, the field of molecular imaging has witnessed tremendous expansion, partly owing to the rapid evolvement of imaging instruments dedicated to small animal studies which enabled non-invasive investigation of many biological events that could not be easily interrogated before these tools became available. This special issue of Current Pharmaceutical Biotechnology will cover a broad array of exciting topics in molecular imaging. Molecular imaging is a pivotal component of future “personalized medicine”. Positron emission tomography (PET) is the most sensitive imaging modality in the clinic. Several review articles in this special issue will focus on different aspects of PET imaging, including novel PET agents in clinical studies, recent development in PET instrumentation, and various methods to label proteins with 18F (the most-widely used PET isotope). A number of strategies have been employed to identify novel agents for molecular imaging applications. Among these, the use of Affibody molecules, development of new probes for melanoma imaging, identification of novel targeting ligands by phage display, and dual-targeted molecular probes for cancer imaging will be reviewed in this issue. Optical imaging is less expensive and more convenient than many other imaging modalities such as PET and magnetic resonance imaging (MRI). Therefore, it can serve as an attractive alternative in preclinical imaging studies since light penetration in small animals is less of a concern than in humans. This special issue will cover several topics in optical imaging such as new optical imaging systems, spectral fluorescence imaging, confocal fluctuation spectroscopy/imaging, imaging with Raman spectroscopy, as well as the recent development of quantum dot (i.e. fluorescent semiconductor nanoparticle) bioconjugates. Cell-based therapies hold enormous potential for treating many diseases and non-invasive imaging is an indispensable tool in monitoring the location and therapeutic efficacy of these cells. Two review articles in this special issue will be dedicated to two of the most intensively studied cell types, T-cells and human embryonic stem cells (hESCs), respectively. The future of “personalized medicine” would greatly benefit from the development of imaging biomarkers that can noninvasively monitor the therapeutic response. The development of agents that can image cell death (apoptosis and/or necrosis) in vivo, the current and future role of hyperpolarized 13CMRI, and the use of diffusion-weighted MRI for assessment of early cancer treatment response in many types of solid tumors, are also reviewed in this issue. Molecular imaging is an extremely dynamic field of research with far-reaching (potential) applications in clinical patient management. For example, 18F-FDG has been routinely used in cancer patient management and it is expected that many other new PET agents will be approved by the Food and Drug Administration (FDA) in the near future. Topics on molecular imaging can easily fill several text books and I sincerely hope that this special issue will provide a “sneak peak” of this highly interdisciplinary and fertile ground of research, which may lead to broad applications of these tools by scientists/clinicians from many different fields in answering their own biological questions of interest.