Validation of Computational Fluid Dynamics in CT-based Airway Models with SPECT/CT

Published Online:https://doi.org/10.1148/radiol.10100322

A combination of CT and computational fluid dynamics yields functional information regarding ventilation of the lower airways that is in agreement with the outcome of combined SPECT/CT.

Purpose

To compare the results obtained by using numerical flow simulations with the results of combined single photon emission computed tomography (SPECT) and computed tomography (CT) and to demonstrate the importance of correct boundary conditions for the numerical methods to account for the large amount of interpatient variability in airway geometry.

Materials and Methods

This study was approved by all relevant institutional review boards. All patients gave their signed informed consent. In this study, six patients with mild asthma (three men; three women; overall mean age, 46 years ± 17 [standard deviation]) underwent CT at functional residual capacity and total lung capacity, as well as SPECT/CT. CT data were used for segmentation and computational fluid dynamics (CFD) simulations. A comparison was made between airflow distribution, as derived with (a) SPECT/CT through tracer concentration analysis, (b) CT through lobar expansion measurement, and (c) CFD through flow computer simulation. Also, the heterogeneity of the ventilation was examined.

Results

Good agreement was found between SPECT/CT, CT, and CFD in terms of airflow distribution and hot spot detection. The average difference for the internal airflow distribution was less than 3% for CFD and CT versus SPECT/CT. Heterogeneity in ventilation patterns could be detected with SPECT/CT and CFD.

Conclusion

This results of this study show that patient-specific computer simulations with appropriate boundary conditions yield information that is similar to that obtained with functional imaging tools, such as SPECT/CT.

© RSNA, 2010

Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100322/-/DC1

References

  • 1 Boiselle PM. Imaging of the large airways. Clin Chest Med 2008;29(1):181–193, vii. Crossref, MedlineGoogle Scholar
  • 2 Coxson HO, Rogers RM. New concepts in the radiological assessment of COPD. Semin Respir Crit Care Med 2005;26(2):211–220. Crossref, MedlineGoogle Scholar
  • 3 Litmanovich D, Boiselle PM, Bankier AA. CT of pulmonary emphysema: current status, challenges, and future directions. Eur Radiol 2009;19(3):537–551. Crossref, MedlineGoogle Scholar
  • 4 Matsuoka S, Kurihara Y, Yagihashi K, Hoshino M, Nakajima Y. Airway dimensions at inspiratory and expiratory multisection CT in chronic obstructive pulmonary disease: correlation with airflow limitation. Radiology 2008;248(3):1042–1049. LinkGoogle Scholar
  • 5 Corren J. Small airways disease in asthma. Curr Allergy Asthma Rep 2008;8(6):533–539. Crossref, MedlineGoogle Scholar
  • 6 de Blic J, Scheinmann P. The use of imaging techniques for assessing severe childhood asthma. J Allergy Clin Immunol 2007;119(4):808–810. Crossref, MedlineGoogle Scholar
  • 7 Nakano Y, Van Tho N, Yamada H, Osawa M, Nagao T. Radiological approach to asthma and COPD: the role of computed tomography. Allergol Int 2009;58(3):323–331. Crossref, MedlineGoogle Scholar
  • 8 Brody AS. Scoring systems for CT in cystic fibrosis: who cares? Radiology 2004;231(2):296–298. LinkGoogle Scholar
  • 9 Loeve M, Lequin MH, de Bruijne Met al.. Cystic fibrosis: are volumetric ultra-low-dose expiratory CT scans sufficient for monitoring related lung disease? Radiology 2009;253(1):223–229. LinkGoogle Scholar
  • 10 Saavedra MT, Lynch DA. Emerging roles for CT imaging in cystic fibrosis. Radiology 2009;252(2):327–329. LinkGoogle Scholar
  • 11 De Backer JW, Vos WG, Devolder Aet al.. Computational fluid dynamics can detect changes in airway resistance in asthmatics after acute bronchodilation. J Biomech 2008;41(1):106–113. Crossref, MedlineGoogle Scholar
  • 12 De Backer JW, Vos WG, Verhulst SL, De Backer W. Novel imaging techniques using computer methods for the evaluation of the upper airway in patients with sleep-disordered breathing: a comprehensive review. Sleep Med Rev 2008;12(6):437–447. Crossref, MedlineGoogle Scholar
  • 13 Lin CL, Tawhai M, McLennan G, Hoffman E. Computational fluid dynamics. IEEE Eng Med Biol Mag 2009;28(3):25–33. Crossref, MedlineGoogle Scholar
  • 14 Anderson J. Computational fluid dynamics. New York, NY: McGraw-Hill, 2001. Google Scholar
  • 15 Nowak N, Kakade PP, Annapragada AV. Computational fluid dynamics simulation of airflow and aerosol deposition in human lungs. Ann Biomed Eng 2003;31(4):374–390. Crossref, MedlineGoogle Scholar
  • 16 Isaacs KK, Schlesinger RB, Martonen TB. Three-dimensional computational fluid dynamics simulations of particle deposition in the tracheobronchial tree. J Aerosol Med 2006;19(3):344–352. Crossref, MedlineGoogle Scholar
  • 17 Longest PW, Vinchurkar S. Effects of mesh style and grid convergence on particle deposition in bifurcating airway models with comparisons to experimental data. Med Eng Phys 2007;29(3):350–366. Crossref, MedlineGoogle Scholar
  • 18 Luo HY, Liu Y, Yang XL. Particle deposition in obstructed airways. J Biomech 2007;40(14):3096–3104. Crossref, MedlineGoogle Scholar
  • 19 Brook BS, Murphy CM, Breen D, Miles AW, Tilley DG, Wilson AJ. Quantification of lung injury using ventilation and perfusion distributions obtained from gamma scintigraphy. Physiol Meas 2007;28(12):1451–1464. Crossref, MedlineGoogle Scholar
  • 20 Newman SP, Pitcairn GR, Hirst PH. A brief history of gamma scintigraphy. J Aerosol Med 2001;14(2):139–145. Crossref, MedlineGoogle Scholar
  • 21 Fleming JS, Epps BP, Conway JH, Martonen TB. Comparison of SPECT aerosol deposition data with a human respiratory tract model. J Aerosol Med 2006;19(3):268–278. Crossref, MedlineGoogle Scholar
  • 22 Suga K, Kawakami Y, Iwanaga H, Tokuda O, Matsunaga N. Automated breath-hold perfusion SPECT/CT fusion images of the lungs. AJR Am J Roentgenol 2007;189(2):455–463. Crossref, MedlineGoogle Scholar
  • 23 Suga K, Yasuhiko K, Iwanaga H, Tokuda O, Matsunaga N. Functional mechanism of lung mosaic CT attenuation: assessment with deep-inspiration breath-hold perfusion SPECT-CT fusion imaging and non-breath-hold Technegas SPECT. Acta Radiol 2009;50(1):34–41. Crossref, MedlineGoogle Scholar
  • 24 Nagao M, Murase K, Ichiki T, Sakai S, Yasuhara Y, Ikezoe J. Quantitative analysis of technegas SPECT: evaluation of regional severity of emphysema. J Nucl Med 2000;41(4):590–595. MedlineGoogle Scholar
  • 25 Xu J, Moonen M, Johansson A, Gustafsson A, Bake B. Quantitative analysis of inhomogeneity in ventilation SPET. Eur J Nucl Med 2001;28(12):1795–1800. Crossref, MedlineGoogle Scholar
  • 26 de Rochefort L, Vial L, Fodil Ret al.. In vitro validation of computational fluid dynamic simulation in human proximal airways with hyperpolarized 3He magnetic resonance phase-contrast velocimetry. J Appl Physiol 2007;102(5):2012–2023. Crossref, MedlineGoogle Scholar
  • 27 Mylavarapu G, Murugappan S, Mihaescu M, Kalra M, Khosla S, Gutmark E. Validation of computational fluid dynamics methodology used for human upper airway flow simulations. J Biomech 2009;42(10):1553–1559. Crossref, MedlineGoogle Scholar
  • 28 De Backer JW, Vos WG, Gorlé CDet al.. Flow analyses in the lower airways: patient-specific model and boundary conditions. Med Eng Phys 2008;30(7):872–879. Crossref, MedlineGoogle Scholar
  • 29 Wilcox DC. Turbulence modeling for CFD. 2nd ed. La Cañada, Calif: DCW Industries, 1998. Google Scholar
  • 30 Usmani OS, Biddiscombe MF, Barnes PJ. Regional lung deposition and bronchodilator response as a function of beta2-agonist particle size. Am J Respir Crit Care Med 2005;172(12):1497–1504. Crossref, MedlineGoogle Scholar
  • 31 Campana L, Kenyon J, Zhalehdoust-Sani Set al.. Probing airway conditions governing ventilation defects in asthma via hyperpolarized MRI image functional modeling. J Appl Physiol 2009;106(4):1293–1300. Crossref, MedlineGoogle Scholar
  • 32 Venegas JG, Winkler T, Musch Get al.. Self-organized patchiness in asthma as a prelude to catastrophic shifts. Nature 2005;434(7034):777–782. Crossref, MedlineGoogle Scholar
  • 33 Gattinoni L, Caironi P, Cressoni Met al.. Lung recruitment in patients with the acute respiratory distress syndrome. N Engl J Med 2006;354(17):1775–1786. Crossref, MedlineGoogle Scholar
  • 34 Verbanck S, Schuermans D, Vincken W. Small airways ventilation heterogeneity and hyperinflation in COPD: response to tiotropium bromide. Int J Chron Obstruct Pulmon Dis 2007;2(4):625–634. MedlineGoogle Scholar
  • 35 Bayat S, Porra L, Suhonen Het al.. Imaging of lung function using synchrotron radiation computed tomography: what’s new? Eur J Radiol 2008;68(3 suppl):S78–S83. Crossref, MedlineGoogle Scholar

Article History

Received February 9, 2010; revision requested April 2; revision received June 21; accepted July 28; final version accepted August 18.
Published online: Dec 2010
Published in print: Dec 2010