Nuclear imaging approaches facilitating nanomedicine translation.

Nanomedicine approaches can effectively modulate the biodistribution and bioavailability of therapeutic agents, improving their therapeutic index. However, despite the ever-increasing amount of literature reporting on preclinical nanomedicine, the number of nanotherapeutics receiving FDA approval remains relatively low. Several barriers exist that hamper the effective preclinical evaluation and clinical translation of nanotherapeutics. Key barriers include insufficient understanding of nanomedicines' in vivo behavior, inadequate translation from murine models to larger animals, and a lack of patient stratification strategies. Integrating quantitative non-invasive imaging techniques in nanomedicine development offers attractive possibilities to address these issues. Among the available imaging techniques, nuclear imaging by positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are highly attractive in this context owing to their quantitative nature and uncontested sensitivity. In basic and translational research, nuclear imaging techniques can provide critical quantitative information about pharmacokinetic parameters, biodistribution profiles or target site accumulation of nanocarriers and their associated payload. During clinical evaluation, nuclear imaging can be used to select patients amenable to nanomedicine treatment. Here, we review how nuclear imaging-based approaches are increasingly being integrated into nanomedicine development and discuss future developments that will accelerate their clinical translation.