The use of 99Tcm-DTPA aerosol ventilation scintigraphy in the diagnosis of pulmonary embolism

Pulmonary scintigraphy is now established as a sensitive and noninvasive method for diagnosing pulmonary embolism (PE). The diagnostic specificity is increased if the perfusion study is combined with assessment of regional ventilation. The latter is usually performed using radioactive gases, either 133Xe or 81Krm, but these have some disadvantages. We report here a method for ventilation scintigraphy using 99Tcm-DTPA aerosol, previously described for the measurement of lung permeability, and present our findings in 20 patients. The system is easy to use and six-view images obtained can be readily compared with perfusion images. No data processing is required and any hospital with gamma camera facilities can use the system. Thus patients with suspected PE can have combined V/Q scintigrams to establish the diagnosis of PE and unnecessary treatment can be avoided.