title: Nitrogen-13: historical review and future perspectives.
abstract: Positron emission tomography is an ultra-sensitive, in vivo molecular imaging technique that allows the determination of the spatiotemporal distribution of a positron emitter labeled radiotracer after administration into living organisms. Among all existing positron emitters, (18) F has been by far the most widely used both in clinical diagnosis and in preclinical investigation, while the use of (11) C significantly increased after the 1980s because of the widespread installation of biomedical cyclotrons. The use of other shorter-lived positron emitters such as (13) N (T1/2  = 9.97 min) has been historically more restricted. Paradoxically, its stable isotope ((14) N) is present in many biological active molecules; consequently, the development of strategies for the efficient incorporation of (13) N into radiotracers would represent an interesting alternative to (11) C- and (18) F-labeling. In the current paper, the developments related to (13) N chemistry are reviewed, including different production routes of primary precursors and their applications to the preparation of more complex (13) N-labeled molecules. The current situation and future perspectives are also briefly discussed.
authors.affiliation: Radiochemistry Department, Molecular Imaging Unit, CIC biomaGUNE; Parque Tecnológico de Miramón, San Sebastián, 20009, Guipúzcoa, Spain.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Gómez-Vallejo
authors.forename: Vijay
authors.initials: V
authors.lastname: Gaja
authors.forename: Kiran B
authors.initials: KB
authors.lastname: Gona
authors.forename: Jordi
authors.initials: J
authors.lastname: Llop
mesh_terms: D000818:Animals; D006801:Humans; D007553:Isotope Labeling; D009590:Nitrogen Radioisotopes; D011854:Radiochemistry
chemical_list: D009590:Nitrogen Radioisotopes
keywords: nitrogen-13; positron emission tomography; radiochemistry; radiotracer