Semi-automated scoring of pulmonary emphysema from X-ray CT: Trainee reproducibility and accuracy

Amir M. Owrangi, Brandon Entwistle, Andrew Lu, Jack Chiu, Nabil Hussain, Roya Etemad-Rezai, Grace Parraga

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Objective We developed a semi-automated tool to quantify emphysema from thoracic X-ray multi-detector (64-slice) computed tomography (CT) for training purposes and multi-reader studies. Materials and Methods Thoracic X-ray CT was acquired in 93 ex-smokers, who were evaluated by six trainees with little or no expertise (trainees) and a single experienced thoracic radiologist (expert). A graphic user interface (GUI) was developed for emphysema quantification based on the percentile of lung where a score of 0 = no abnormalities, 1 = 1-25%, 2 = 26-50%, 3 = 51-75% and 4 = 76-100% for each lung side/slice. Trainees blinded to subject characteristics scored randomized images twice; accuracy was determined by comparison to expert scores, density histogram 15th percentile (HU 15), relative area at -950 HU (RA950), low attenuation clusters at -950 HU (LAC950), -856 HU (LAC856) and the diffusing capacity for carbon monoxide (DLCO%pred). Intra- and inter-observer reproducibility was evaluated using coefficients-of-variation (COV), intra-class (ICC) and Pearson correlations. Results Trainee-expert correlations were significant (r = 0.85-0.97, p < 0.0001) and a significant trainee bias (0.15 ± 0.22) was observed. Emphysema score was correlated with RA950 (r = 0.88, p < 0.0001), HU15 (r = -0.77, p < 0.0001), LAC950 (r = 0.76, p < 0.0001), LAC856 (r = 0.74, p = 0.0001) and DLCO%pred (r = -0.71, p < 0.0001). Intra-observer reproducibility (COV = 4-27%; ICC = 0.75-0.94) was moderate to high for trainees; intra- and inter-observer COV were negatively and non-linearly correlated with emphysema score. Conclusion We developed a GUI for rapid and interactive emphysema scoring that allows for comparison of multiple readers with clinical and radiological standards.

Original languageEnglish (US)
Pages (from-to)e734-e741
JournalEuropean Journal of Radiology
Issue number11
StatePublished - Nov 2013


  • COPD
  • Computed tomography
  • Emphysema
  • Subjective quantification

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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