The patient is a 65-year-old male with a history of right femoral thrombosis
and a recent cardiac arrest who is currently anticoagulated on heparin. He is referred for
evaluation of a possible acute pulmonary embolism.
Multiple bilateral mismatched segmental defects are identified. Under PIOPED
criteria, this study is consistent with a high probability for an acute
pulmonary embolism. The differential diagnosis includes chronic pulmonary