SPECT and PET imaging of adrenomedullin receptors: a promising strategy for studying pulmonary vascular diseases

Circulating adrenomedullin (AM) levels are elevated in several cardiovascular diseases, including pulmonary vascular diseases causing pulmonary hypertension. To date the perfusion agent Tc-99m-albumin macroaggregates (MAA) is the only approved radiopharmaceutical used for imaging of pulmonary circulation. Unlike Tc-99m-MAA, imaging the AM receptors involves a molecular process dependent on the density of the receptors and the affinity of specific radioligands. The AM receptors are abundantly distributed in lung capillaries and its integrity provides protection in the development of pulmonary vascular diseases. This review summarizes the development and characterization of radioligands for in vivo imaging of AM receptors as an early predictor of the onset of a pulmonary vascular disease.