Deep and precise lighting-up/combat diseases through sonodynamic agents integrating molecular imaging and therapy modalities

Phototherapy including photodynamic therapy (PDT) and photothermal therapy (PTT) has been widely applied to treat various diseases. Regrettably, phototherapy still has several limitations in practical applications, such as the poor tissue penetration of excitation light, unsatisfactory therapy efficiency, tumor hypoxia and the short lifetime of the generated reactive oxygen species, and undesired damage to normal tissues. By utilizing the cooperation of low-intensity ultrasound (US) and sonosensitizers, the novel treatment approach, sonodynamic therapy (SDT) has the power to overcome the main limitations of phototherapy due to its inherent deep tissue penetrating capability. Despite the achieved great progress and success, SDT still faces the issue of precisely tracing the sonosensitizers and evaluating the therapy efficiency during the sonodynamic therapy. To guide the process of SDT, the design of multifunctional sonosensitizers integration with the modern imaging techniques should be considered. On the other hand, traditional mono-therapy modality of SDT still faces the challenge of limited therapy efficiency and continuous administration during the entire therapy period, which can be effectively resolved by the complement of SDT and other therapy modalities. This review summarizes the applications of SDT in combination with molecular imaging techniques and other therapeutic modalities. Moreover, we further discuss the potential clinical translation and the future prospects of SDT.