Quantitative Analysis of Computed Tomography Scans of the Lungs for the Diagnosis of Pulmonary Emphysema: A Validation Study of a Semiautomated Contour Detection Technique

RATIONALE AND OBJECTIVES.To develop an analytic software package based on automated contour detection for the objective and reproducible assessment of emphysema from computed tomography (CT) scans. METHODS.A semiautomated technique was developed for the definition of lung contours in CT cross-sections followed by the assessment of pulmonary CT parameters describing the disease state. For 78 images, the semiautomated contour detection was performed and compared with contours drawn by an experienced radiologist by calculating the systematic area difference (bias) and differences in pulmonary CT parameters such as the mean lung density (MLD). In addition, intraobserver and interobserver variabilities were determined in a subset of 15 images. RESULTS.The areas enclosed by the semiautomatically detected contours were slightly larger than the manual ones (bias