Correlation of high-resolution CT and pulmonary function in bronchiolitis obliterans: a study based on 24 patients associated with consumption of Sauropus androgynus.

OBJECTIVE

An outbreak of Sauropus androgynus-associated bronchiolitis obliterans occurred in Taiwan in the summer of 1995. We undertook a study of the correlation between high-resolution CT findings and pulmonary function testing in patients from this outbreak.

MATERIALS AND METHODS

We evaluated inspiratory-expiratory high-resolution CT scans of 24 patients with S. androgynus-associated bronchiolitis obliterans. The presence of bronchiectasis was assessed by two visual scores (a bronchial dilatation score and a bronchiectasis extent score). Extent of air-trapping was assessed visually and given a score. We also used computer software to assess the extent of air-trapping and generate scores of dynamic attenuation. Spirometry, plethysmography, and diffusion capacity of each patient were also obtained.

RESULTS

All four scores had statistically significant correlation with forced expiratory volume in 1 sec (FEV1) (p < .05 for both bronchiectasis scores; p < .001 for both air-trapping scores). The two air-trapping scores had statistically significant correlation with forced vital capacity and diffusion capacity. We found the scores for dynamic attenuation had the greatest correlation with FEV1 (r = .85). We also found that mosaic attenuation was notable on expiratory CT scans alone in nine patients (type 1 air-trapping) and on both inspiratory and expiratory CT scans in 15 patients (type 2 air-trapping). In the latter group, FEV1 was significantly lower (p < .01).

CONCLUSION

Findings from high-resolution CT of air-trapping were more important than findings of bronchiectasis when correlating pulmonary function with S. androgynus-associated bronchiolitis obliterans. Type 2 air-trapping suggested a more severe air-flow obstruction than did type 1. Scores for quantitative attenuation generated by computer software were helpful in assessing air-trapping and correlating it with pulmonary function. These findings may apply to patients with bronchiolitis obliterans from other causes.