Pulmonary emphysema: comparison of preoperative quantitative CT and physiologic index values with clinical outcome after lung-volume reduction surgery.

Abstract

To compare quantitative computed tomographic (CT) and preoperative physiologic values in emphysema with outcome after lung-volume reduction surgery. In 46 patients, emphysema was quantified by measuring lung attenuation on preoperative CT scans. Quantitative CT and preoperative physiologic values and postoperative outcomes (1-second forced expiratory volume, PaO2, and 6-minute walk distance) were compared. Moderately strong correlations were found between several quantitative CT and preoperative physiologic values (magnitude of r = .29-.58, P < .05) and several quantitative CT and outcome measures (magnitude of r = .31-.47, P < .05). With stratification, postoperative outcome was better with mean lung attenuation greater than -900 HU; 75% or greater of upper lung below -900 HU (emphysema index); greater than 25% of lung below -960 HU (severe emphysema index); ratio of upper- and lower-lung emphysema indexes 1.5 or greater; volume of normally attenuated lung (-850 to -701 HU) greater than 1 L; and full width at half maximum of attenuation-frequency distribution 80 HU or less. Differences in outcome measures between groups stratified with quantitative CT values were often two- to threefold; patients with greater numbers of favorable quantitative CT values had better outcome. Correlations between preoperative physiologic measures and outcome were few. In emphysema, quantitative CT values correlate with outcome. Quantitative assessment of emphysema in candidates for lung-volume reduction surgery is potentially useful.