Hemoptysis
Hemoptysis is generally secondary to chronic bronchitis or bronchiectasis (60-70% of cases). Other etiologies include pneumonia, bronchogenic carcinoma, tuberculosis, pulmonary embolism, vasculitis, pulmonary AVM, and trauma. Hemoptysis tends to occur intermittently and recur sporadically. It can be life threatening if massive (greater than 1000 ml/24 hours) due to asphyxiation from aspiration of the blood.
Labeled RBC's have also been used in cases of hemoptysis to localize the site of
pulmonary hemorrhage. The scan has been shown to be positive in about 50% of patients and
can detect bleeding rates as low as 50 ml/day. Labeled red blood cells are the preferred
imaging agent (rather than Tc-SC) due to the intermittent nature of the hemorrhage.