N-isopropyl-p-[I-123]iodoamphetamine lung imaging in a patient with chronic pulmonary thromboembolism

A patient with a brain infarct was found to have chronic pulmonary embolism associated with perfusion defects on blood flow imaging with N-isopropyl-p-[I-123]iodoamphetamine (I-123 IMP). However, gradually increasing uptake of I-123 IMP was seen in later images, in areas distal to the embolus. The increased uptake to the embolized lung seemed to be through the systemic collateral circulation.