Comparative Analysis of Visual Emphysema Detection with Low Attenuation Area Quantification: A Systematic Review

Objectives To systematically review CT-based LAA% for emphysema quantification, explore the application of percentage low attenuation area (LAA% below -950HU), in comparison with visual emphysema scoring. Methods Following PRISMA-DTA guidelines, searches were conducted (01-01-1972 to 01-04-2026) in PubMed, Embase®, and Web of Science databases to identify English-language studies of adults ≥18 years with CT-quantified emphysema. Two independent readers screened titles, abstracts and full texts against predefined inclusion/exclusion criteria. Studies comparing LAA%-quantified emphysema with visual scores were included. Results 737 studies were reviewed, 5 (0.7%) met the eligibility criteria. These studies originated from Asia, Europe and the United States. LAA% cut-off values for emphysema varied: two studies used a 6% threshold, one used 5%, another used 1.5%, and one applied ordinal severity thresholds from 1% to 25%. Visual classification also differed, with three studies using the Fleischner Society system, one using a modified 3-point score, and another using the Goddard classification. Agreement between visual assessment and LAA%-based quantification was generally poor, with reported kappa values of 0.22 (n = 1,221), -0.06 (n = 200), and 0.48 (n = 98). Two studies further reported agreement based on sensitivity (86.8% and 58.0%) and specificity (84.2% and 39.0%). Conclusions Based on limited evidence, substantial heterogeneity exists between visual assessment and LAA% quantification in emphysema. Discordance between visual and quantitative CT assessment likely reflects differences in diagnostic criteria and technical characteristics, highlighting the need for standardized reporting and methodology. Advances in knowledge This systematic review provides a comprehensive comparison of visual scoring and LAA% metrics. It demonstrates limited agreement and substantial methodological heterogeneity of CT assessment of emphysema.