Comparison of standard- and low-radiation-dose CT for quantification of emphysema.

OBJECTIVE This study was performed to compare standard- and low-radiation-dose techniques in the CT quantification of emphysema. MATERIALS AND METHODS The study population consisted of 36 men and 20 women who were current or former heavy smokers and underwent standard-dose (effective tube current, 100-250 mAs) chest CT at our institution within 6 months of having undergone low-dose (effective tube current, 30-60 mAs) chest CT. All CT scans were reconstructed at 5-mm slice thickness with a smooth filter. CT-measured lung volume, mean and median lung attenuation, and percentage of lung volume with attenuation lower than multiple thresholds (emphysema index values) were compared by Pearson correlation, two-tailed and paired Student's t tests, and regression analysis. RESULTS There were no significant differences in mean attenuation (-848 vs -846 H, p > 0.35) for the low dose and the standard dose or in median lung attenuation (-879 vs -878 H, p > 0.66). Low- and standard-dose emphysema indexes were correlated at all attenuation thresholds (r = 0.86-0.97). Mean emphysema indexes were higher on the low-dose scans, but the mean difference at all thresholds was less than 3%. The differences were significant (p < 0.05) only at the lower index thresholds, correlated with differences in lung volume (r < or = 0.86), and increased with greater differences in dose. CONCLUSION Low-dose technique has minimal effect on CT quantification of emphysema.

[1]  H A Vrooman,et al.  A randomized clinical trial of alpha(1)-antitrypsin augmentation therapy. , 1999, American journal of respiratory and critical care medicine.

[2]  B. Siewert,et al.  Missed lesions at abdominal oncologic CT: lessons learned from quality assurance. , 2008, Radiographics : a review publication of the Radiological Society of North America, Inc.

[3]  Jonathan G Goldin,et al.  Emphysema: effect of reconstruction algorithm on CT imaging measures. , 2004, Radiology.

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

[5]  F D Thomas,et al.  Density patterns in the normal lung as determined by computed tomography. , 1980, Radiology.

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

[7]  A. Buecker,et al.  Low-dose MDCT for surveillance of patients with severe homogeneous emphysema after bronchoscopic airway bypass. , 2008, AJR. American journal of roentgenology.

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

[9]  Paul Pinsky,et al.  Baseline findings of a randomized feasibility trial of lung cancer screening with spiral CT scan vs chest radiograph: the Lung Screening Study of the National Cancer Institute. , 2004, Chest.

[10]  Milan Sonka,et al.  Integrated system for CT-based assessment of parenchymal lung disease , 2002, Proceedings IEEE International Symposium on Biomedical Imaging.

[11]  R M Slone,et al.  Pulmonary emphysema: comparison of preoperative quantitative CT and physiologic index values with clinical outcome after lung-volume reduction surgery. , 1997, Radiology.

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

[13]  E. Hoffman,et al.  Characterization of the interstitial lung diseases via density-based and texture-based analysis of computed tomography images of lung structure and function. , 2003, Academic radiology.

[14]  P. Paré,et al.  A quantification of the lung surface area in emphysema using computed tomography. , 1999, American journal of respiratory and critical care medicine.

[15]  L Kreel,et al.  Pulmonary tissue attenuation with computed tomography: comparison of inspiration and expiration scans. , 1979, Journal of computer assisted tomography.

[16]  Michael F McNitt-Gray,et al.  AAPM/RSNA Physics Tutorial for Residents: Topics in CT. Radiation dose in CT. , 2002, Radiographics : a review publication of the Radiological Society of North America, Inc.

[17]  Stefano Diciotti,et al.  Prevalence and correlates of pulmonary emphysema in smokers and former smokers. A densitometric study of participants in the ITALUNG trial , 2008, European Radiology.

[18]  Anne-Marie Sykes,et al.  CT screening for lung cancer: five-year prospective experience. , 2005, Radiology.

[19]  Yoshikazu Inoue,et al.  Quantitative CT in chronic obstructive pulmonary disease: inspiratory and expiratory assessment. , 2009, AJR. American journal of roentgenology.

[20]  J. Best,et al.  DIAGNOSIS OF PULMONARY EMPHYSEMA BY COMPUTERISED TOMOGRAPHY , 1984, The Lancet.

[21]  J. Best,et al.  CT measurements of lung density in life can quantitate distal airspace enlargement--an essential defining feature of human emphysema. , 1988, The American review of respiratory disease.

[22]  W. Heindel,et al.  Screening for early lung cancer with low-dose spiral computed tomography: results of annual follow-up examinations in asymptomatic smokers , 2004, European Radiology.

[23]  Jonathan G Goldin,et al.  A pilot study of all-trans-retinoic acid for the treatment of human emphysema. , 2002, American journal of respiratory and critical care medicine.

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

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

[26]  S. Sone,et al.  Results of three-year mass screening programme for lung cancer using mobile low-dose spiral computed tomography scanner , 2001, British Journal of Cancer.