The role of Tc-99m DTPA aerosol scintigraphy in the differential diagnosis of COPD and asthma.

Objective: Chronic obstructive lung disease (COPD) and asthma are characterized as similar to each other in causing airway obstruction and being an inflammatory process. The purpose of this study was to investigate whether technetium-99m diethylenetriaminepentaacetic acid ((99m) Tc-DTPA) aerosol scintigraphy could be used in the differential diagnosis of asthma and COPD.

Methods: Eighty-four patients (male/female: 32/52; mean age 50.2 ± 12.7 years) with obstructive lung disease and 30 healthy volunteers as the control group were enrolled in the study. The patients were divided into two groups as COPD and asthma and also smoking subgroups. Alveolar clearance study was performed using a radiolabeled aerosol of (99m) Tc-DTPA. Mucociliary clearance was evaluated with T½ , cap value and penetration index parameters. All patient underwent pulmonary function tests and Forced expiratory volume (FEV1 ), forced vital capacity (FVC) and FEV1 /FVC parameters were obtained.

Results: The mean of T½ values of (99m) Tc-DTPA aerosol and FEV1 /FVC value among spirometric tests of the nonsmoking COPD patients were significantly lower than nonsmoking asthma patients (46.1 ± 14.3, 62.3 ± 18.7, P = 0.02; 65.2 ± 10.8, 81.4 ± 16.5, P = 0.04, respectively). The cap value was significantly higher in nonsmoking COPD patients (1.21 ± 0.49, 0.76 ± 0.22, P = 0.03). While there were no statistically and significantly different between control and asthmatic groups at the scintigraphic parameters and spirometric parameters, the mean of T½ values, cap value and spirometric parameters were statistically different between control and COPD groups (P < 0.05).

Conclusion: We showed that assessment of mucociliary permeability with (99m) Tc-DTPA aerosol scintigraphy was a useful, easy to apply and a noninvasive technique to use in the differential diagnosis of nonsmoker COPD and asthma.