Gadolinium agents for theragnosis of malignant tumors

Imaging agents are essential in diagnosing malignant tumors. Various elements are currently used as imaging agents in various chemical forms; gadolinium for magnetic resonance imaging (MRI), iodine for X-ray computed tomography (CT), and radioisotopes with short half-lives for positron emission tomography (PET). Among them, gadolinium is a special element which possesses outstanding theragnostic (e.g. diagnostic and therapeutic) properties for malignant tumors such as brain tumors, which are superior to all elements currently used clinically in various chemical forms. That is, gadolinium agents in nanoparticle or chelate forms can be used as MRI contrast agents or CT contrast agents to diagnose malignant tumors, and neutron capture therapy (NCT) agents to treat malignant tumors. Therefore, one gadolinium chemical in either chelate or nanoparticle forms could be used for theragnosis of malignant tumors. In this Opinion Article, researches conducted so far are briefly introduced, and outstanding theragnostic properties of gadolinium and what needs to happen before gadolinium agents can be applied to malignant tumor theragnosis, are discussed.