Bronchoscopic treatment for emphysema and asthma: bronchoscopic lung volume reduction

Heterogenous disease This is de ned as greater than 10 per cent variation in the emphysematous destruction between the upper and lower lobes. A more accurate way of assessing this is by applying a density mask to lung windows and areas with an attenuation value of less than 910 Hounds eld units on 10 mm computed tomography (CT) sections (Fig. 15.1).