Pulmonary hypertension (PH) can be the result of various clinical conditions. It may be idiopathic or associated with various cardiovascular and lung disorders. Currently there is no test that can non-invasively detect abnormalities of the pulmonary circulation. There is a growing need for a non-invasive method to detect PH. There currently exists only ne agent approved in Canada for clinical imaging of the pulmonary circulation, 99mTc-labeled macroaggregates. This agent is exclusively used for the diagnosis of physical defects of the circulation due to pulmonary embolus. This agent is larger than small pulmonary vessels, limiting its sensitivity to detect small vascular defects, as well as potential infectious risks since albumin macroaggregates are derived from human albumin. There is need then for new lung tracers that could provide a greater safety profile while enabling functional as well as anatomical imaging of the pulmonary circulation. DFH-12 (PulmoBind) is a peptide derived from human adrenomedullin (hAMI-52). Hence the development of this novel AM derivative, PulmoBind, for molecular imaging of the pulmonary circulation. PulmoBind is labeled with 99mTc, the most commonly used imaging isotope in nuclear medicine.