Background: Low-dose erythromycin therapy improves
airflow limitation and airway inflammation in patients with diffuse
panbronchiolitis (DPB). However, to our knowledge there has been no
study to determine whether physiologic improvement during erythromycin
therapy correlates with radiologic findings.
objective: To clarify whether improvement in pulmonary function
correlates with specific changes on chest CT.
The relationship between five CT findings and five pulmonary function
parameters was evaluated before and 3 months after low-dose
erythromycin therapy in 24 patients with DPB retrospectively.
Results: After erythromycin therapy, the predicted
percentage of vital capacity (%VC; 87.0 ± 3.07% vs
98.9 ± 3.39%; p = 0.00006) and 50% of the maximum midexpiratory
flow rate of FVC (1.41 ± 0.26 L/s vs 1.61 ± 0.27 L/s; p = 0.03)
significantly increased, and the residual volume/total lung capacity
ratio (RV/TLC%; 44.5 ± 1.93% vs 40.7 ± 1.83%; p = 0.0019)
significantly decreased, but the FEV1 to FVC ratio and 25%
of the maximum expiratory flow rate of FVC did not. In five CT
findings, centrilobular nodules (3.7 ± 0.4 vs 1.5 ± 0.3;
p = 0.0001), peripheral bronchiolar wall thickness (3.8 ± 0.3 vs
2.6 ± 0.4; p = 0.0007), and peripheral bronchiolectasis
(2.8 ± 0.3 vs 2.2 ± 0.4; p = 0.0058) had significantly
improved, whereas low attenuation area and central bronchiectasis had
not. There were positive correlations of improved scores of
centrilobular nodules with improved %VC (r = 0.58,
p = 0.0062) and RV/TLC% (r = 0.64,
p = 0.0022).
Conclusions: Decreased air
trapping in DPB correlates with an improvement of centrilobular
nodules, which reflects the obstructive lesions of bronchioles during
the erythromycin therapy.