124Iodine: A Longer-Life Positron Emitter Isotope—New Opportunities in Molecular Imaging

Abstract

124Iodine (124I) with its 4.2 d half-life is particularly attractive forin vivodetection and quantification of longer-term biological and physiological processes; the long half-life of124I is especially suited for prolonged timein vivostudies of high molecular weight compounds uptake. Numerous small molecules and larger compounds like proteins and antibodies have been successfully labeled with124I. Advances in radionuclide production allow the effective availability of sufficient quantities of124I on small biomedical cyclotrons for molecular imaging purposes. Radioiodination chemistry with124I relies on well-established radioiodine labeling methods, which consists mainly in nucleophilic and electrophilic substitution reactions. The physical characteristics of124I permit taking advantages of the higher PET image quality. The availability of new molecules that may be targeted with124I represents one of the more interesting reasons for the attention in nuclear medicine. We aim to discuss all iodine radioisotopes application focusing on124I, which seems to be the most promising for its half-life, radiation emissions, and stability, allowing several applications in oncological and nononcological fields.