Eur Radiol (2010) 20: 2882–2889 DOI 10.1007/s00330-010-1866-8 COMPUTED TOMOGRAPHY Sven F. Thieme Sandra Hoegl Konstantin Nikolaou Juergen Fisahn Michael Irlbeck Daniel Maxien Maximilian F. Reiser Christoph R. Becker Thorsten R. C. Johnson Received: 20 January 2010 Revised: 13 May 2010 Accepted: 21 May 2010 Published online: 23 June 2010 # European Society of Radiology 2010 Pulmonary ventilation and perfusion imaging with dual-energy CT Abstract Objective To evaluate the feasibility of dual-energy CT (DECT) ventilation imaging in combination with DE perfusion mapping for a comprehensive assessment of ventilation, perfusion, morphology and structure of the pulmonary parenchyma. Methods Two dual-energy CT acquisitions for xenon-enhanced ventilation and iodine-enhanced perfusion mapping were performed in patients under artificial respiration. Parenchymal xenon and iodine distribution were mapped and correlated with structural or vascular abnormalities. Results In all datasets, image quality was sufficient for a comprehensive image reading of the pulmonary CTA images, lung window images and pulmonary functional parameter maps and led to expedient results in each patient. Conclusion With dual-source CT systems, DECT of the lung with iodine or xenon administration is technically feasible and makes it possible to depict the regional iodine or xenon distribution representing the local perfusion and ventilation. Keywords Dual-energy CT . Lung ventilation CT . Functional lung imaging . Dual-energy functional pulmonary CT . Xenon ventilation CT Introduction Whenever high-resolution morphological information on structural changes of the lung parenchyma is needed, CT is the first-line imaging technique, applying so-called high- resolution (HR) protocols with a narrow reconstructed slice thickness and a high-resolution reconstruction algorithm. In the field of functional lung imaging, dual-energy CT (DECT) using dual-source CT (DSCT) systems with two independent tube–detector units makes improved material differentiation feasible [1]. Previous studies have shown that DECT can map the iodine distribution in the lung parenchyma and detect perfusion changes or defects [2–7]. Thus, DECT is able to combine morphological and func- tional lung imaging. The inert gas xenon (Xe) has X-ray absorption characteristics that resemble those of iodine, so it can serve as an inhalant contrast agent for CT ventilation imaging. Although there have been trials in previous decades using stable xenon gas for CT ventilation imaging, this method had not been used in clinical care. These previous approaches were based on sequential acquisitions, implying an increased patient dose and potential misregistrations due to varying levels of inspira- tion [8–13]. With dual-source CT systems that can acquire two spiral CT datasets with different photon spectra simultaneously, DECT now has the potential to map xenon distribution patterns by directly visualising the inhaled xenon gas. Chae et al. performed xenon-enhanced DECT in 12 subjects at an inspiratory xenon concentration S. F. Thieme : K. Nikolaou : D. Maxien : M. F. Reiser : C. R. Becker : T. R. C. Johnson Department of Clinical Radiology, Ludwig Maximilians University, Klinikum Großhadern, Marchioninistr. 15, 81377, München, Germany S. Hoegl : J. Fisahn : M. Irlbeck Department of Anesthesiology, Ludwig Maximilians University, Klinikum Großhadern, Marchioninistr. 15, 81377, München, Germany S. F. Thieme ()) Institut für Klinische Radiologie der LMU München, Klinikum Großhadern, Marchioninistr. 15, 81377, München, Germany e-mail: sven.thieme@med.lmu.de Tel.: +49-89-70953620