Monitoring of smoking-induced emphysema with CT in a lung cancer screening setting: detection of real increase in extent of emphysema.

PURPOSE To retrospectively establish the minimum increase in emphysema score (ES) required for detection of real increased extent of emphysema with 95% confidence by using multi-detector row computed tomography (CT) in a lung cancer screening setting. MATERIALS AND METHODS The study was a substudy of the NELSON project that was approved by the Dutch Ministry of Health and the ethics committee of each participating hospital, with patient informed consent. For this substudy, original approval and informed consent allowed use of data for future research. Among 1684 men screened with low-dose multi-detector row CT (30 mAs, 16 detector rows, 0.75-mm section thickness) between April 2004 and March 2005, only participants who underwent repeat multi-detector row CT with the same scanner after 3 months because of an indeterminate pulmonary nodule were included. Extent of emphysema was considered to remain stable in this short period. Extent of low-attenuation areas representing emphysema was computed for repeat and baseline scans as percentage of lung volume below three attenuation threshold values (-910 HU, -930 HU, -950 HU). Limits of agreement were determined with Bland-Altman approach; upper limits were used to deduce the minimum increase in ES required for detecting increased extent of emphysema with 95% probability. Factors influencing the limits of agreement were determined. RESULTS In total, 157 men (mean age, 60 years) were included in the study. Limits of agreement for differences in total lung volume between repeat and baseline scans were -13.4% to +12.6% at -910 HU, -4.7% to +4.2% at -930 HU, and -1.3% to +1.1% at -950 HU. Differences in ES showed weak to moderate correlation with variation in level of inspiration (r=0.20-0.49, P<.05). Scanner calibration could be excluded as a factor contributing to variation in ES. CONCLUSION Increase in ES required to detect increased extent of smoking-related emphysema with 95% probability varies between 1.1% of total lung volume at -950 HU and 12.6% at -910 HU for low-dose multi-detector row CT. Clinical trial registration no. ISRCTN63545820.

[1]  J. Habbema,et al.  [Screening for lung cancer in the Netherlands: the role of spiral CT scan]. , 2001, Nederlands tijdschrift voor geneeskunde.

[2]  Michelle Hilts,et al.  Image filtering for improved dose resolution in CT polymer gel dosimetry. , 2003, Medical physics.

[3]  T. Church.  Chest radiography as the comparison for spiral CT in the National Lung Screening Trial. , 2003, Academic radiology.

[4]  J. Habbema,et al.  Risk‐based selection from the general population in a screening trial: Selection criteria, recruitment and power for the Dutch‐Belgian randomised lung cancer multi‐slice CT screening trial (NELSON) , 2007, International journal of cancer.

[5]  Feng Li,et al.  Mass screening for lung cancer with mobile spiral computed tomography scanner , 1998, The Lancet.

[6]  R. Nakashima,et al.  Emphysema detected by lung cancer screening with low‐dose spiral CT: Prevalence, and correlation with smoking habits and pulmonary function in Japanese male subjects , 2006, Respirology.

[7]  Y. Nakano,et al.  Optimized scanning conditions of high resolution CT in the follow-up of pulmonary emphysema. , 1999, Journal of computer assisted tomography.

[8]  T Isomura,et al.  Lung cancer screening: minimum tube current required for helical CT. , 2000, Radiology.

[9]  Lene Theil Skovgaard,et al.  Progress of emphysema in severe α1-Antitrypsin Deficiency as Assessed by Annual CT , 1997 .

[10]  P De Vuyst,et al.  Comparison of computed density and macroscopic morphometry in pulmonary emphysema. , 1995, American journal of respiratory and critical care medicine.

[11]  N H Holstein-Rathlou,et al.  Volume adjustment of lung density by computed tomography scans in patients with emphysema , 2004, Acta radiologica.

[12]  P. Gevenois,et al.  Quantitative computed tomography assessment of lung structure and function in pulmonary emphysema. , 2001, The European respiratory journal.

[13]  A. Dirksen,et al.  Short‐term reproducibility of computed tomography‐based lung density measurements in alpha‐1 antitrypsin deficiency and smokers with emphysema , 2004, Acta radiologica.

[14]  P. Gevenois,et al.  Pulmonary emphysema: objective quantification at multi-detector row CT--comparison with macroscopic and microscopic morphometry. , 2006, Radiology.

[15]  J. V. van Engelshoven,et al.  Chronic obstructive pulmonary disease: evaluation with spirometrically controlled CT lung densitometry. , 1994, Radiology.

[16]  W A Kalender,et al.  Measurement of pulmonary parenchymal attenuation: use of spirometric gating with quantitative CT. , 1990, Radiology.

[17]  Jan Stolk,et al.  Optimization and Standardization of Lung Densitometry in the Assessment of Pulmonary Emphysema , 2004, Investigative radiology.

[18]  G J Kemerink,et al.  CT lung densitometry: dependence of CT number histograms on sample volume and consequences for scan protocol comparability. , 1997, Journal of computer assisted tomography.

[19]  J. Clausen,et al.  Quantitation of emphysema with three-dimensional CT densitometry: comparison with two-dimensional analysis, visual emphysema scores, and pulmonary function test results. , 1999, Radiology.

[20]  J. Golden,et al.  Low-Dose, Dynamic, Expiratory Thin-Section CT of the Lungs Using a Spiral CT Scanner , 2000, Journal of thoracic imaging.

[21]  G. Chatellier,et al.  Pulmonary nodules: preliminary experience with three-dimensional evaluation. , 2004, Radiology.

[22]  D. Altman,et al.  STATISTICAL METHODS FOR ASSESSING AGREEMENT BETWEEN TWO METHODS OF CLINICAL MEASUREMENT , 1986, The Lancet.

[23]  N J Morrison,et al.  Quantitation of emphysema by computed tomography using a "density mask" program and correlation with pulmonary function tests. , 1990, Chest.

[24]  O. Miettinen,et al.  Early Lung Cancer Action Project: overall design and findings from baseline screening , 1999, The Lancet.

[25]  Eric A. Hoffman,et al.  Automatic lung segmentation for accurate quantitation of volumetric X-ray CT images , 2001, IEEE Transactions on Medical Imaging.

[26]  Y. Yamashita,et al.  Assessment of lung volumes in pulmonary emphysema using multidetector helical CT: comparison with pulmonary function tests. , 2001, Computerized medical imaging and graphics : the official journal of the Computerized Medical Imaging Society.

[27]  Bram van Ginneken,et al.  Local noise weighted filtering for emphysema scoring of low-dose CT images , 2006, IEEE Transactions on Medical Imaging.

[28]  Jan Stolk,et al.  Influence of calibration on densitometric studies of emphysema progression using computed tomography. , 2004, American journal of respiratory and critical care medicine.

[29]  R M Slone,et al.  Repeatability of quantitative CT indexes of emphysema in patients evaluated for lung volume reduction surgery. , 2001, Radiology.

[30]  N. Müller,et al.  "Density mask". An objective method to quantitate emphysema using computed tomography. , 1988, Chest.

[31]  B C Stoel,et al.  Validation of computed tomographic lung densitometry for monitoring emphysema in α1-antitrypsin deficiency , 2006, Thorax.