A clinical comparison between Technegas SPECT, CT, and pulmonary function tests in patients with emphysema

Pulmonary emphysema can be easily diagnosed by X-ray CT (CT) as low attenuation areas. Recently 99mTc Technegas has been used for ventilation scintigraphy. The present study was undertaken to assess the usefulness of SPECT images using Technegas scintigraphy and CT, as compared with pulmonary function tests in patients with pulmonary emphysema. Fifteen patients were examined. We classified and defined the score according to the findings of Technegas scintigraphy (Technegas) images into four grades, from Score 0 to Score 3, and those of CT into five grades, from Score 0 to Score 4, both from normal to severe. The right lung was divided into nine segments, and the left into eight. To obtain the average of the entire lung, the total score from both lungs was divided by 17. These average scores in for SPECT and CT were compared with the results of pulmonary function tests. The average score of Technegas correlated well with % forced expiratory volume in one second (%FEV1.0) (r = 0.87), and forced expiratory volume in one second % (FEV1.0%) (r = 0.83). These results were better than those provided by CT. The average scores of the upper and lower lung fields were also calculated. The score in the upper lung field was higher than that in the lower field. Technegas can assess ventilation impairment in pulmonary emphysema more easily than CT, especially in the upper lung field.