Advances in multimodal imaging techniques in nanomedicine: enhancing drug delivery precision

Nanosystems that deliver drugs have revolutionized modern therapy via the accurate targeting and controlled release of drugs. The importance of real-time monitoring of these systems lies in the evaluation of their pharmacokinetics and biodistribution, as well as preventative treatment efficacy. Imaging methods thus gave birth to real-time monitoring, allowing visualization of nanoparticles (NPs) inside biological systems. This review introduces current imaging techniques such as optical imaging, computed tomography (CT), magnetic resonance imaging (MRI), nuclear imaging, ultrasound, and finally, hybrid techniques that are on the verge of being used. The principles, merits, demerits, and applications of each modality in tracking nanodrug delivery are summarized. Special importance is given to multimodal imaging based on the fact that it can help to overcome the limitations of any individual imaging modality, thereby offering better insight into drug delivery. Advances in imaging probes and imaging-guided drug delivery systems are illustrated to show this transformation of imaging in nanomedicine.