Computed Tomography

European Radiology

, Volume 22, Issue 2, pp 287-294

Reproducibility of volume and densitometric measures of emphysema on repeat computed tomography with an interval of 1 week

  • Daniel ChongAffiliated withCenter for Computer Vision and Imaging Biomarkers, David Geffen School of Medicine, UCLA Email author 
  • , Matthew S. BrownAffiliated withCenter for Computer Vision and Imaging Biomarkers, Department of Radiological Sciences, David Geffen School of Medicine, UCLA
  • , Hyun J. KimAffiliated withCenter for Computer Vision and Imaging Biomarkers, Department of Radiological Sciences, David Geffen School of Medicine, UCLA
  • , Eva M. van RikxoortAffiliated withCenter for Computer Vision and Imaging Biomarkers, David Geffen School of Medicine, UCLA
  • , Laura GuzmanAffiliated withCenter for Computer Vision and Imaging Biomarkers, David Geffen School of Medicine, UCLA
  • , Michael F. McNitt-GrayAffiliated withCenter for Computer Vision and Imaging Biomarkers, Department of Radiological Sciences, David Geffen School of Medicine, UCLA
  • , Maryam KhatonabadiAffiliated withCenter for Computer Vision and Imaging Biomarkers, David Geffen School of Medicine, UCLA
  • , Maya Galperin-AizenbergAffiliated withCenter for Computer Vision and Imaging Biomarkers, David Geffen School of Medicine, UCLA
  • , Heidi CoyAffiliated withCenter for Computer Vision and Imaging Biomarkers, David Geffen School of Medicine, UCLA
    • , Katherine YangAffiliated withCenter for Computer Vision and Imaging Biomarkers, David Geffen School of Medicine, UCLA
    • , Yongha JungAffiliated withCenter for Computer Vision and Imaging Biomarkers, David Geffen School of Medicine, UCLA
    • , Jonathan G. GoldinAffiliated withCenter for Computer Vision and Imaging Biomarkers, Department of Radiological Sciences, David Geffen School of Medicine, UCLA

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Abstract

Objectives

The reproducibilities of CT lung volume and densitometric measures of emphysema were assessed over 1 week. The influence of breathhold on reproducibility was assessed.

Methods

HRCT was performed on 44 subjects at inspiration on two visits with a 7-day interval. CT lung volume, relative area below -950HU (RA950-raw), and 15th percentile density (PD15-raw) were computed. Volume correction was used to obtain RA950-adj and PD15-adj. Reproducibilities between visits were assessed using concordance correlation coefficient (CCC) and repeatability coefficient (RC). Reproducibilities were compared between raw and adjusted measures. Differences between visits were computed for volume and density measures. Correlations were computed for density differences versus volume difference. Subgroup analysis was performed using a 0.25 L volume difference threshold.

Results

High CCC were observed for all measures in full group (CCC > 0.97). Reproducibilities of volume (RC = 0.67 L), RA950-raw (RC = 2.3%), and PD15-raw (RC = 10.6HU) were observed. Volume correction significantly improved PD15 (RC = 3.6HU) but not RA950 (RC = 1.7%). RA950-raw and PD15-raw had significantly better RC in <0.25 L subgroup than ≥0.25 L. Significant correlations with volume were observed for RA950-raw and PD15-raw (R 2 > 0.71), but not RA950-adj or PD15-adj (R 2 < 0.11).

Conclusions

Good breathhold and RA950 reproducibilities were achieved. PD15 was less reproducible but improved with volume correction or superior breathhold reproduction.

Key Points

Good breath-hold reproducibility is achievable between multiple CT examinations.

Reproducibility of densitometric measures may be improved by statistical volume correction.

Volume correction may result in decreased signal.

Densitometric reproducibility may also be improved by achieving good breath-hold reproduction.

Careful consideration of signal and noise is necessary in reproducibility assessment.

Keywords

Chronic obstructive pulmonary disease Pulmonary emphysema X-ray computed tomography Densitometry Reproducibility