Difference in low attenuation area (LAA) of the lungs on high resolution computed tomography (HRCT) between asthma and pulmonary emphysema in relation to cigarette smoking

The low attenuation area (LAA) of the lungs on high resolution computed tomography (HRCT) was evaluated in 20 asthmatics (10 ex-smokers and 10 never-smokers) and 10 patients with pulmonary emphysema (all ex-smokers) by ventilatory function, lung volume, DLco, and a ratio of expiratory LAA/inspiratory LAA. 1 . The % LAA of the lungs on HRCT was significantly larger in patients with pulmonary emphysema(PE) than in those with asthma, but there was not significant difference in % LAA between ex-smokers and never-smokers of asthmatics. 2. A ratio of expiratory Winspiratory LAA was significantly higher in patients with PE than in those with asthma , and the ratio was significantly higher in ex-smokers of asthmatics than in never-smokers (p<0.05). 3 . The difference in % residual volume and % DLco was significant between asthma and PE , and between ex - smokers and never-smokers of asthmatics (% RV : p<0.05, DLco : p<0.05) . 4 . The difference in the values of % FVC, % FEV(1) .O, and FEV1.0% was significant between asthma and PE, but not significant between ex-smokers and never- smokers of asthmatics. The results suggest that the difference in a ratio of expiratory W inspiratory LAA, % RV and % DLco was significant between ex - smokers and never - smokers of asthmatics , and cigarette smoking induces more irreversible changes of the lungs.

気管支喘息20例（10例：喫煙例，10例非喫煙例）および肺気腫10例（全例喫煙例）を対象に，high resolution computed tomography（HRCT）上の肺のlow attenuation area（LAA）の臨床的意義に ついて検討を加えた。 1．HRCT上の肺の% LAAは，肺気腫において気管支喘息に比べ有意に高い値を示したが，気管支喘息の喫煙例と非喫煙例の間には有意に差は見られなかった。 2．呼気LAA/吸気LAA比は，喘息症例に比べ肺気腫症例で有意に高い値を示した。また，喘息の中では，喫煙例で非喫煙例に比べ有意に高い値が示された。 3．% RVおよび% DLcoは，肺気腫と喘息症例との間で，また喘息症例では，喫煙例と非喫煙例の間で有意の差が見られた。 4．% FVC，% FEV1.0およびFEV1.0%値はいずれも．肺気腫と喘息の間では有意の差が見られたが，喘息の喫煙例と非喫煙例の間には有意の差は見られなかった。以上の結果より，肺気腫と喘息の間では全てのパラメーターで有意差が，また喘息の喫煙例と非喫煙例の間では，呼気LAA/吸気LAA比，% RV，% DLcoで有意差が見られることが示唆された。