BRONCHIECTASIS - FUNCTIONAL-SIGNIFICANCE OF AREAS OF DECREASED ATTENUATION AT EXPIRATORY CT

PURPOSE: To characterize areas of decreased attenuation on expiratory computed tomographic (CT) scans in patients with bronchiectasis. MATER IALS AND METHODS: CT scans were obtained at full inspiration and end e xpiration in 70 patients with chronic purulent sputum production. Insp iratory scans were scored at a lobar level for the extent of bronchiec tasis, and inspiratory and expiratory scans were scored for the presen ce and extent of areas of decreased attenuation. Total lobar observati ons were analyzed (n = 840). RESULTS: Bronchiectasis was identified in 434 of 840 lobar observations. The total decreased attenuation score was related to extent of bronchiectasis (r = .49; P < .001), independe nt of functional indexes. Negative correlations were found between for ced expiratory volume in 1 second (FEV(1)) and total decreased attenua tion score (P < .002) and FEV(1) to forced vital capacity ratio (P < . 004) but ndt with indexes of gas transfer. CONCLUSION: Areas of decrea sed attenuation on expiratory CT scans are common in severe bronchiect asis. Such areas in lobes without overt bronchiectasis suggest that sm all airways disease may precede the development of bronchiectasis.