Spirometry vs CT Scan

In diagnosing emphysema, which test is more conclusive, the spirometry or the CT scan.  My spirometry tests numbers are low but 3 CT scan show clear.  Thank you so much!

[National Jewish Health]

Although it is possible, it is unlikely to have no signs on a CT scan with spirometry evidence suggestive of "moderate emphysema".  Simple spirometry reflects airway obstruction to airflow.  The CT scan images reflect the sites and degree of emphysema.  Beyond simple spirometry, a reduced diffusion test would be suggestive but not diagnostic of emphysema.

There is a loose but imperfect correlation between the degree of airway obstruction and the CT scan demonstration of anatomic emphysema.

All this assumes that we are talking about a good quality, high-resolution CT scan.  The first step would be to confirm that.  The second step would be to confirm the validity of the spiromety testing and the validity of the interpretation of the results.