Dual-Energy CT Pulmonary Angiography: Quantification of Disease Burden and Impact on Management
Purpose of Review
Computed tomography pulmonary angiography (CTPA) has become the imaging modality of choice for patients with suspected pulmonary embolism (PE). Post-processing techniques currently available for dual-energy CT pulmonary angiography (DE-CTPA) enhance image quality and provide additional value in the diagnosis of PE. The objective of this article is to summarize these recent developments and discuss the appropriate use of DE-CTPA post-processing applications.
DE-CTPA post-processing applications enable reconstruction of virtual monoenergetic images (VMI) and color-coded iodine-perfusion maps to increase contrast conditions and visualize lung perfusion defects in case of embolic occlusion of pulmonary arteries. Both techniques revealed a superior diagnostic performance for the detection of pulmonary emboli and assessment of the pulmonary perfusion compared to the standard image reconstructions.
DE-CTPA is a well-established method for excluding or diagnosing PE. Continued developments in DE-CTPA post-processing techniques improve patient management and allow for a quantification of disease burden.
KeywordsDual-energy computed tomography Computed tomography pulmonary angiography Pulmonary embolism Pulmonary perfusion Diagnostic accuracy
Compliance with Ethical Guidelines
Conflict of interest
Simon S. Martin, Marly van Assen, L. Parkwood Griffith, Maximilian J. Bauer, and Thomas J. Vogl each declare no potential conflicts of interest. Carlo N. De Cecco reports a grant from Siemens. Akos Varga-Szemes reports a grant from Siemens and is a consultant for Guerbet. Julian L. Wichmann reports personal fees from Siemens and GE Healthcare. U. Joseph Schoepf reports receives institutional research support from Astellas, Bayer, General Electric, and Siemens Healthineers. Dr. Schoepf has received honoraria for speaking and consulting from Bayer, Guerbet, HeartFlow Inc., and Siemens Healthineers.
Human and Animal Rights Statement
All reported studies/experiments with human or animal subjects performed by the authors have been previously published and complied with all applicable ethical standards (including the Helsinki declaration and its amendments, institutional/national research committee standards, and international/national/institutional guidelines).
Recently published papers of particular interest have been highlighted as: ∙ Of importance
- 1.Members ATF, Konstantinides SV, Torbicki A, Agnelli G, Danchin N, Fitzmaurice D, et al. 2014 ESC guidelines on the diagnosis and management of acute pulmonary embolism: The Task Force for the Diagnosis and Management of Acute Pulmonary Embolism of the European Society of Cardiology (ESC) Endorsed by the European Respiratory Society (ERS). Eur Heart J. 2014;35(43):3033–73.Google Scholar
- 5.Wittram C, Maher MM, Yoo AJ, Kalra MK, Shepard JA, McLoud TC. CT angiography of pulmonary embolism: diagnostic criteria and causes of misdiagnosis. Radiographics: a review publication of the Radiological Society of North America, Inc. 2004;24(5):1219–38.Google Scholar
- 15.Green J. Pressure-flow relationships of the pulmonary circulation. Mechanical concepts in cardiovascular and pulmonary physiology. Philadelphia: Lea and Febiger; 1977. p. 55–65.Google Scholar
- 20.Szucs-Farkas Z, Schibler F, Cullmann J, Torrente JC, Patak MA, Raible S, et al. Diagnostic accuracy of pulmonary CT angiography at low tube voltage: intraindividual comparison of a normal-dose protocol at 120 kVp and a low-dose protocol at 80 kVp using reduced amount of contrast medium in a simulation study. Am J Roentgenol. 2011;197(5):W852–9.Google Scholar
- 21.Fanous R, Kashani H, Jimenez L, Murphy G, Paul NS. Image quality and radiation dose of pulmonary CT angiography performed using 100 and 120 kVp. Am J Roentgenol. 2012;199(5):990–6.Google Scholar
- 22.Hou DJ, Tso DK, Davison C, Inacio J, Louis LJ, Nicolaou S, et al. Clinical utility of ultra high pitch dual source thoracic CT imaging of acute pulmonary embolism in the emergency department: are we one step closer towards a non-gated triple rule out? Eur J Radiol. 2013;82(10):1793–8.PubMedGoogle Scholar
- 23.Mourits MM, Nijhof WH, van Leuken MH, Jager GJ, Rutten MJ. Reducing contrast medium volume and tube voltage in CT angiography of the pulmonary artery. Clin Radiol. 2016;71(6):615e7–e13.Google Scholar
- 24.Faggioni L, Neri E, Sbragia P, Pascale R, D’Errico L, Caramella D, et al. 80-kV pulmonary CT angiography with 40 mL of iodinated contrast material in lean patients: comparison of vascular enhancement with iodixanol (320 mg I/mL) and iomeprol (400 mg I/mL). Am J Roentgenol. 2012;199(6):1220–5.Google Scholar
- 29.Schuhbaeck A, Achenbach S, Layritz C, Eisentopf J, Hecker F, Pflederer T, et al. Image quality of ultra-low radiation exposure coronary CT angiography with an effective dose < 0.1 mSv using high-pitch spiral acquisition and raw data-based iterative reconstruction. Eur Radiol. 2013;23(3):597–606.PubMedGoogle Scholar
- 36.Eusemann C, Holmes DR, Schmidt B, Flohr TG, Robb R, McCollough C, et al., editors. Dual energy CT: How to best blend both energies in one fused image? Medical Imaging 2008: Visualization, Image-guided Procedures, and Modeling; 2008: International Society for Optics and Photonics.Google Scholar
- 44.Wildberger JE, Schoepf UJ, Mahnken AH, Herzog P, Ditt H, Niethammer MU, et al., editors. Approaches to CT perfusion imaging in pulmonary embolism. Seminars in roentgenology; 2005: Elsevier.Google Scholar
- 49.Kang M-J, Park CM, Lee C-H, Goo JM, Lee HJ. Dual-energy CT: clinical applications in various pulmonary diseases. Radiographics: a review publication of the Radiological Society of North America, Inc. 2010;30(3):685–98.Google Scholar
- 55.Grant KL, Flohr TG, Krauss B, Sedlmair M, Thomas C, Schmidt B. Assessment of an advanced image-based technique to calculate virtual monoenergetic computed tomographic images from a dual-energy examination to improve contrast-to-noise ratio in examinations using iodinated contrast media. Invest Radiol. 2014;49(9):586–92.PubMedGoogle Scholar
- 57.Wichmann JL, Gillott MR, De Cecco CN, Mangold S, Varga-Szemes A, Yamada R, et al. Dual-energy computed tomography angiography of the lower extremity runoff: impact of noise-optimized virtual monochromatic imaging on image quality and diagnostic accuracy. Invest Radiol. 2016;51(2):139–46.PubMedGoogle Scholar
- 60.∙ Weiss J, Notohamiprodjo M, Bongers M, Schabel C, Mangold S, Nikolaou K, et al. Effect of noise-optimized monoenergetic postprocessing on diagnostic accuracy for detecting incidental pulmonary embolism in portal-venous phase dual-energy computed tomography. Investig Radiol. 2017;52(3):142–7. This study evaluated diagnostic accuracy of virtual monoenergetic images at low keV levels for the detection of incidental PE in oncological follow-up DECT staging examinations. The authors revealed that these reconstructions improved diagnostic accuracy with the highest subjective diagnostic confidence at 55 keV. Google Scholar
- 61.∙ Leithner D, Wichmann JL, Vogl TJ, Trommer J, Martin SS, Scholtz JE, et al. Virtual monoenergetic imaging and iodine perfusion maps improve diagnostic accuracy of dual-energy computed tomography pulmonary angiography with suboptimal contrast attenuation. Investig Radiol. 2017;52(11):659–65. This study showed that DECT noise-optimized virtual monoenergetic image reconstructions and iodine perfusion maps improve reader confidence and diagnostic accuracy for segmental PE detection. Google Scholar
- 65.Meinel FG, Nance JW, Jr., Schoepf UJ, Hoffmann VS, Thierfelder KM, Costello P, et al. Predictive value of computed tomography in acute pulmonary embolism: systematic review and meta-analysis. Am J Med. 2015;128(7):747–59e2.Google Scholar
- 69.van der Meer RW, Pattynama PM, van Strijen MJ, van den Berg-Huijsmans AA, Hartmann IJ, Putter H, et al. Right ventricular dysfunction and pulmonary obstruction index at helical CT: prediction of clinical outcome during 3-month follow-up in patients with acute pulmonary embolism. Radiology. 2005;235(3):798–803.PubMedGoogle Scholar
- 70.Chae EJ, Seo JB, Jang YM, Krauss B, Lee CW, Lee HJ, et al. Dual-energy CT for assessment of the severity of acute pulmonary embolism: pulmonary perfusion defect score compared with CT angiographic obstruction score and right ventricular/left ventricular diameter ratio. AJR Am J Roentgenol. 2010;194(3):604–10.PubMedGoogle Scholar
- 72.Apfaltrer P, Bachmann V, Meyer M, Henzler T, Barraza JM, Gruettner J, et al. Prognostic value of perfusion defect volume at dual energy CTA in patients with pulmonary embolism: correlation with CTA obstruction scores, CT parameters of right ventricular dysfunction and adverse clinical outcome. Eur J Radiol. 2012;81(11):3592–7.PubMedGoogle Scholar
- 73.∙ Im DJ, Hur J, Han KH, Lee HJ, Kim YJ, Kwon W, et al. Acute pulmonary embolism: retrospective cohort study of the predictive value of perfusion defect volume measured with dual-energy CT. AJR Am J Roentgenol. 2017;209(5):1015–22. The authors of this study investigated the incremental risk stratification benefit of DECT findings compared with the RV/LV ventricular diameter ratio in patients with acute PE. However, lung perfusion defect volumes had no statistically significant added benefit for prediction of death among patients with acute PE. Google Scholar