Radiolabeled cell-surface
peptide receptor-binding molecules are emerging as an important class of
radiopharmaceuticals. Their binding to specific cell membrane receptors allows for noninvasive assessment of regional receptor proteomics in vivo. Information thus obtained can be used for diagnostic purposes and for predicting and monitoring response to treatment. This paradigm also applies to
pulmonary diseases. In this review, available
radiopharmaceuticals of great potential or already in clinical use for imaging of
lung cancer,
lung inflammation and
infection and
pulmonary embolism are discussed. In
lung cancer,
somatostatin receptor imaging by means of technetium-99m (99mTc)-octreotide scintigraphy has proven useful for characterizing
malignancy in
solitary pulmonary nodules. Additionally, several
radiopharmaceuticals targeting
tyrosine-kinase, e.g. 99mTc labeled
epidermal growth factor and
indium-111 (111In)-diethylene triamine
penta-
acetic acid-
trastuzumab, or
G-protein coupled receptors, e.g. 99mTc-bombesin, iodine-123-vasoactive intestinal
peptide and 111In-tetraazacyclododecane tetra-
acetic acid (
DOTA)-cholecystokinine-B, are being explored for their diagnostic as well as treatment monitoring potential. With the purpose of better evaluating the source of
pulmonary embolism, as well as to differentiate acute from chronic
deep venous thrombosis, several radiolabeled
peptides targeting the
glycoprotein IIb/IIIa
fibrinogen receptor found on activated platelets have been developed. Out of these,
99mTc-P280 is now approved by the US Food and Drug Administration for scintigraphic imaging of suspected acute
venous thrombosis in the lower extremities of patients. In the field of
lung inflammation and
infection, non-specific 111In and 99mTc-human polyclonal
immunoglobulins have been successfully used to identify the presence and extent of Pneumocystis carinii, cytomegalovirus, Mycobaterium avium and
fungal infections in patients with
HIV infection. The clinical role of other
radiopharmaceuticals such as 99mTc-J001X, a nonpyrogenic acylated polygalactoside isolated from Klebsiella pneumoniae and binding with high affinity to CD11b and CD14
lipopolysaccharide receptors expressed on monocytes/macrophages, and
111In-octreotide, binding to up-regulated
somatostatin receptors on activated lymphocytes needs to be further defined.