Paired Inspiratory/Expiratory Volumetric Thin-Slice CT Scan for Emphysema Analysis: Comparison of Different Quantitative Evaluations and Pulmonary Function Test

doi:10.1378/chest.128.5.3212

Chest

Volume 128, Issue 5, November 2005, Pages 3212-3220

https://doi.org/10.1378/chest.128.5.3212 Get rights and content

Purpose: The aim of the study was to use three-dimensional high-resolution CT scan data sets in inspiration and expiration for the quantitative evaluation of emphysema. Using an advanced dedicated semiautomatic analysis tool, the functional inspiratory/expiratory shifts of emphysema volume and clusters were quantified. The pulmonary function test (PFT) served as the clinical “gold standard.”

Materials and methods: Thirty-one patients (9 women and 22 men; mean [± SD] age, 60 ± 8 years) who had severe emphysema due to COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] class III and IV) were included in the study. All patients underwent paired inspiratory/expiratory multidetector CT scans (slice thickness, 1/0.8 mm) and pulmonary function tests (PFTs). CT scan data were analyzed with self-written emphysema detection solftware. It provides lung volume (LV), emphysema volume (EV), emphysema index (EI), and four clusters of emphysema with different volumes (from 2, 8, 65, and 120 mm³). These results were correlated with total lung capacity (TLC), intrathoracic gas volume (ITGV), and residual volume (RV) derived from PFT results.

Results: Inspiratory LV correlated with TLC (r= 0.9), expiratory LV with ITGV (r= 0.87), and RV (r= 0.83). Expiratory EV correlated better with ITGV (r= 0.88) and RV (r= 0.93) than with inspiratory EV (r= 0.83 and 0.88, respectively). The mean inspiratory EI was 54 ± 13%, and it decreased to 43 ± 15% in expiration. However, the individuals showed a broad spectrum of changes of EI (mean, 11%; range, 1 to 28%), and no differences in inspiratory/expiratory EI and changes in EI or LV were found between GOLD III and GOLD IV patients. In expiration, there was a change from the large emphysema cluster (-37%) to the intermediate cluster (+15%) and small cluster (+13% and +11%, respectively). The change of volume of the large emphysema cluster after expiration correlated well with the changes in LV (r= 0.9), EV (r= 0.99), EI (r= 0.85), and MLD (r= 0.76).

Conclusion: Emphysema volumes measured from expiratory MDCT scans better reflect PFT abnormalities in patients with severe emphysema than those from inspiratory scans. Volumetric cluster analysis provided deeper insights into the local hyperinflation and expiratory obstruction of large emphysematous clusters.

Section snippets

MATERIALS AND METHODS

From December 2003 until December 2004, we examined 31 consecutive patients (9 women and 22 men; mean [± SD] age, 60 ± 8 years; age range, 41 to 76 years). All patients had severe emphysema due to COPD. Classification was performed according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD), as follows: GOLD class II, 2 patients; GOLD class III, 17 patients; and GOLD class IV, 12 patients (mean FEV₁, 35 ± 11% predicted; FEV₁range, 64 to 20%). They presented with shortness of

RESULTS

All examinations were eligible for evaluation. In all cases, the leading CT scan diagnosis was severe centrilobular emphysema with architectural destruction. No large emphysema bullae or areas of ground-glass opacity, which could suggest other disease patterns such as alveolitis or bronchiolitis obliterans, were detected.

The results of PFTs are summarized inTable 1. The results of the CT scan evaluation for inspiration and expiration are presented inTable 2. Beside the volumes, the absolute

DISCUSSION

We found a high correlation between quantitative parameters derived from MD scans that obtained at deep inspiration and deep expiration, and the results of PFT. The EV at expiration correlated even better with ITGV and RV than the EV at inspiration. During expiration, there was a volume loss in the large emphysema cluster, which corresponded to an increase in volume in the intermediate and small clusters. The absolute change in EV was attributed to the large cluster.

Until now, spiral CT scan

CONCLUSION

EVs measured from expiratory MD better reflect PFT result abnormalities in patients with severe emphysema than those from inspiratory MDCT scans. Cluster analysis provides deeper insights into local hyperinflation and the expiratory obstruction of large emphysematous clusters.

ACKNOWLEDGMENTS

The authors are grateful to Emphasys Medical Inc to be able to participate in the VENT Trial. Many thanks to Mrs. A. Fuxa for technical assistance. The data are part of the doctoral thesis of Ms. Serap Erdugan, MS.

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: Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

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Chest

Clinical Investigations: COPDPaired Inspiratory/Expiratory Volumetric Thin-Slice CT Scan for Emphysema Analysis: Comparison of Different Quantitative Evaluations and Pulmonary Function Test

Section snippets

MATERIALS AND METHODS

RESULTS

DISCUSSION

CONCLUSION

ACKNOWLEDGMENTS

Radiol Clin North Am

Radiol Clin North Am

Chest

Chest

Radiol Clin North Am

Comput Med Imaging Graph

Acad Radiol

Chest

Chest

Lancet

J Thorac Cardiovasc Surg

Evidence-based health policy: lessons from the Global Burden of Disease Study.

Science

The definition of emphysema: report of a National Heart, Lung, and Blood Institute, Division of Lung Diseases workshop.

Am Rev Respir Dis

Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: National Heart, Lung, and Blood Institute and World Health Organization Global Initiative for Chronic Obstructive Lung Disease (GOLD); executive summary.

Respir Care

Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. Executive summary, updated 2004. Available at

CT quantification of pulmonary emphysema: assessment of lung structure and function.

Crit Rev Comput Tomogr

Comparison of computed density and macroscopic morphometry in pulmonary emphysema.

Am J Respir Crit Care Med

Computed tomographic measurements of airway dimensions and emphysema in smokers: correlation with lung function.

Am J Respir Crit Care Med

Clinical Investigations: COPD
Paired Inspiratory/Expiratory Volumetric Thin-Slice CT Scan for Emphysema Analysis: Comparison of Different Quantitative Evaluations and Pulmonary Function Test