Chronic obstructive pulmonary disease: evaluation with spirometrically controlled CT lung densitometry.

PURPOSE: To compare the computed tomographic (CT) lung densitometry results in patients with chronic obstructive pulmonary disease (COPD) and in control subjects (healthy persons). MATERIALS AND METHODS: Spirometrically gated CT sections at 5 cm above and 5 cm below the carina at 90% and 10% vital capacity (VC) were imaged in patients and controls. Various densitometric parameters were derived from the CT data, and results were compared between the two levels of inspiration. RESULTS: Densitometric results in patients with emphysema were substantially different from those in patients with chronic bronchitis and in controls at 90% and 10% VC. Differences in patients with chronic bronchitis and in controls were not significant at 90% VC but were significant at 10% VC (P < .001). The mean changes in densitometric parameters between 90% and 10% VC were substantially greater in controls than in patients with COPD. CONCLUSION: It may be possible to classify lung disease with only two CT sections obtained at the same anatomic level, one at 90% and one at 10% VC, irrespective of the densitometric parameter used.