Regional Heterogeneity of Air Trapping at Expiratory Thin-Section CT of Patients with Bronchiolitis: Potential Implications for Dose Reduction and CT Protocol Planning

Purpose: To prospectively determine whether the regional distribution of air trapping in patients with suspected or overt bronchiolitis is heterogeneous, and to determine the effect that a simulated reduction of computed tomographic (CT) sections and of scanned anatomic regions would have on the assessment of the extent of air trapping.

Materials and Methods: For this Ethical Committee–approved study, multi–detector row CT (collimation, 4 × 1 mm; rotation time, 0.5 second; 140 kVp; and 80 effective mAs) was performed in 47 lung transplant recipients (23 women, 24 men; mean age, 41 years ± 12 [standard deviation]; 18 without bronchiolitis, 18 with potential bronchiolitis, and 11 with bronchiolitis, as determined by lung function measurements). Images were reconstructed with a thickness of 1 mm at an increment of 10 mm. The extent of air trapping in the upper, middle, and lower lung regions was correlated. Differences between regions and the interaction between patients and regions were tested with an analysis of variance. The extent of air trapping was calculated for six simulated examination protocols.

Results: Correlations between the upper and middle (r = 0.930), the upper and lower (r = 0.756), and the middle and lower lung regions (r = 0.863) were significant (P < .001). The extent of air trapping increased from the upper to the lower lung region, with significant differences between regions (P < .001). There was a significant interaction between patients and lung regions (P < .001). Simulated examination protocols resulted in significantly different extents of air trapping (P < .001).

Conclusion: The regional distribution of the extent of air trapping in suspected or overt bronchiolitis is heterogeneous. Because the extent of air trapping can depend on the examination protocol, identical protocols are needed when air trapping is being compared within and between patients.

© RSNA, 2008


  • 1 Hansell DM, Rubens MB, Padley SP, Wells AU. Obliterative bronchiolitis: individual CT signs of small airways disease and functional correlation. Radiology 1997; 203: 721–726. LinkGoogle Scholar
  • 2 Hansell DM. Small airways diseases: detection and insights with computed tomography. Eur Respir J 2001;17:1294–1313. Crossref, MedlineGoogle Scholar
  • 3 Pipavath SJ, Lynch DA, Cool C, Brown KK, Newell JD. Radiologic and pathologic features of bronchiolitis. AJR Am J Roentgenol 2005;185:354–363. Crossref, MedlineGoogle Scholar
  • 4 Studler U, Gluecker T, Bongartz G, Roth J, Steinbrich W. Image quality from high-resolution CT of the lung: comparison of axial scans and of sections reconstructed from volumetric data acquired using MDCT. AJR Am J Roentgenol 2005;185:602–607. Crossref, MedlineGoogle Scholar
  • 5 Bankier AA, Schaefer-Prokop C, De Maertelaer V, et al. Air trapping: comparison of standard-dose and simulated low-dose thin-section CT techniques. Radiology 2007;242:898–906. LinkGoogle Scholar
  • 6 Lee KW, Chung SY, Yang I, Lee Y, Ko EY, Park MJ. Correlation of aging and smoking with air trapping at thin-section CT of the lung in asymptomatic subjects. Radiology 2000;214:831–836. LinkGoogle Scholar
  • 7 Webb WR, Stern EJ, Kanth N, Gamsu G. Dynamic pulmonary CT: findings in healthy adult men. Radiology 1993;186:117–124. LinkGoogle Scholar
  • 8 Standardization of spirometry, 1994 update: American Thoracic Society. Am J Respir Crit Care Med 1995;152:1107–1136. Crossref, MedlineGoogle Scholar
  • 9 Quanjer PH, Tammeling GJ, Cotes JE, Pedersen OF, Peslin R, Yernault JC. Lung volumes and forced ventilatory flows: report working party standardization of lung function tests, European Community for Steel and Coal—official statement of the European Respiratory Society. Eur Respir J Suppl 1993;16:5–40. Crossref, MedlineGoogle Scholar
  • 10 Estenne M, Maurer JR, Boehler A, et al. Bronchiolitis obliterans syndrome 2001: an update of the diagnostic criteria. J Heart Lung Transplant 2002;21:297–310. Crossref, MedlineGoogle Scholar
  • 11 Hemminger BM. Calibration of CRT monitors according to the DICOM grayscale standard display function [abstr]. Radiology 1999;213(P):583. LinkGoogle Scholar
  • 12 Worthy SA, Muller NL, Hartman TE, Swensen SJ, Padley SP, Hansell DM. Mosaic attenuation pattern on thin-section CT scans of the lung: differentiation among infiltrative lung, airway, and vascular diseases as a cause. Radiology 1997;205:465–470. LinkGoogle Scholar
  • 13 Arakawa H, Webb WR. Air trapping on expiratory high-resolution CT scans in the absence of inspiratory scan abnormalities: correlation with pulmonary function tests and differential diagnosis. AJR Am J Roentgenol 1998;170:1349–1353. Crossref, MedlineGoogle Scholar
  • 14 Leung AN, Fisher K, Valentine V, et al. Bronchiolitis obliterans after lung transplantation: detection using expiratory HRCT. Chest 1998;113:365–370. Crossref, MedlineGoogle Scholar
  • 15 Miller WT Jr, Kotloff RM, Blumenthal NP, Aronchick JM, Gefter WB, Miller WT. Utility of high resolution computed tomography in predicting bronchiolitis obliterans syndrome following lung transplantation: preliminary findings. J Thorac Imaging 2001;16:76–80. Crossref, MedlineGoogle Scholar
  • 16 Gevenois PA, De Vuyst P, Sy M, et al. Pulmonary emphysema: quantitative CT during expiration. Radiology 1996;199:825–829. LinkGoogle Scholar
  • 17 Copley SJ, Wells AU, Muller NL, et al. Thin-section CT in obstructive pulmonary disease: discriminatory value. Radiology 2002;223:812–819. LinkGoogle Scholar
  • 18 Bankier AA, Van Muylem A, Knoop C, Estenne M, Gevenois PA. Bronchiolitis obliterans syndrome in heart-lung transplant recipients: diagnosis with expiratory CT. Radiology 2001;218:533–539. LinkGoogle Scholar
  • 19 Bankier AA, Van Muylem A, Scillia P, De Maertelaer V, Estenne M, Gevenois PA. Air trapping in heart-lung transplant recipients: variability of anatomic distribution and extent at sequential expiratory thin-section CT. Radiology 2003;229:737–742. LinkGoogle Scholar
  • 20 Choi YW, Rossi SE, Palmer SM, DeLong D, Erasmus JJ, McAdams HP. Bronchiolitis obliterans syndrome in lung transplant recipients: correlation of computed tomography findings with bronchiolitis obliterans syndrome stage. J Thorac Imaging 2003;18:72–79. Crossref, MedlineGoogle Scholar
  • 21 Mastora I, Remy-Jardin M, Sobaszek A, Boulenguez C, Remy J, Edme JL. Thin-section CT finding in 250 volunteers: assessment of the relationship of CT findings with smoking history and pulmonary function test results. Radiology 2001;218:695–702. LinkGoogle Scholar
  • 22 Worthy SA, Park CS, Kim JS, Muller NL. Bronchiolitis obliterans after lung transplantation: high-resolution CT findings in 15 patients. AJR Am J Roentgenol 1997;169:673–677. Crossref, MedlineGoogle Scholar
  • 23 Lee ES, Gotway MB, Reddy GP, Golden JA, Keith FM, Webb WR. Early bronchiolitis obliterans following lung transplantation: accuracy of expiratory thin-section CT for diagnosis. Radiology 2000;216:472–477. LinkGoogle Scholar
  • 24 Konen E, Gutierrez C, Chaparro C, et al. Bronchiolitis obliterans syndrome in lung transplant recipients: can thin-section CT findings predict disease before its clinical appearance? Radiology 2004;231:467–473. Google Scholar
  • 25 Knollmann FD, Ewert R, Wundrich T, Hetzer R, Felix R. Bronchiolitis obliterans syndrome in lung transplant recipients: use of spirometrically gated CT. Radiology 2002;225:655–662. LinkGoogle Scholar
  • 26 de Jong PA, Dodd JD, Coxson HO, et al. Bronchiolitis obliterans following lung transplantation: early detection using computed tomographic scanning. Thorax 2006;61:799–804. Crossref, MedlineGoogle Scholar
  • 27 Tanaka N, Matsumoto T, Miura G, et al. Air trapping at CT: high prevalence in asymptomatic subjects with normal pulmonary function. Radiology 2003;227:776–785. LinkGoogle Scholar
  • 28 Berstad AE, Aalokken TM, Kolbenstvedt A, Bjortuft O. Performance of long-term CT monitoring in diagnosing bronchiolitis obliterans after lung transplantation. Eur J Radiol 2006;58:124–131. Crossref, MedlineGoogle Scholar
  • 29 Cohen J. Weighted kappa: nominal scale agreement with provision for scaled disagreement or partial credit. Psychol Bull 1968;70:213–220. Crossref, MedlineGoogle Scholar
  • 30 Liebetrau AM. Measures of association. In: Sage University papers on quantitative applications in the social sciences, series 07-032. Newbury Park, Calif: Sage, 1983; 32–36. Google Scholar
  • 31 Arcasoy SM, Kotloff RM. Lung transplantation. N Engl J Med 1999;340:1081–1091. Crossref, MedlineGoogle Scholar
  • 32 Estenne M, Hertz MI. Bronchiolitis obliterans after human lung transplantation. Am J Respir Crit Care Med 2002;166:440–444. Crossref, MedlineGoogle Scholar

Article History

Published in print: 2008