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. 2025 Jan 18;168(1):43–55. doi: 10.1016/j.chest.2024.12.037

Figure 1.

Figure 1

Inspiratory (A, C) and expiratory (B, D) CT scans from 2 patients of different occupations at GOLD stage 1 with similar spirometry but different small airway measures. Patient 1 (silk worker): 8-h TWA endotoxin = 0 EU/m3; spirometry: pp FEV1 = 0.808; small airway measures: Exp−856 = 0.057, E/I MLA = 0.759, RVC−856 to −950 = –0.477, Residual−856 = –0.164. Patient 2 (cotton worker): 8-h TWA endotoxin = 4,890 EU/m3; spirometry: pp FEV1 = 0.803; small airway measures: Exp−856 = 0.422, E/I MLA = 1.001, RVC−856 to −950 = 0.006, Residual−856 = 0.266. E/I MLA = expiratory-to-inspiratory ratio of mean lung attenuation; Exp−856 = percentage of voxels with attenuation less than –856 HU on expiratory CT scans; GOLD = Global Initiative for Chronic Obstructive Lung Disease; pp FEV1 = percent predicted FEV1; HU = Hounsfield unit; Residual–856 = residuals from the linear regression of Exp−856 on the percentage of voxels with attenuation less than –950 HU; RVC−856 to −950 = relative volume change in voxels with attenuation between –856 HU and –950 HU; TWA = time-weighted average.