Diagnostics What is the clinical significance of chest CT when the chest x-ray result is normal in patients with blunt trauma?☆ , ☆☆ , ★ Bory Kea MD a, ⁎ , 1 , Ruwan Gamarallage MBBS a , Hemamalini Vairamuthu, MBBS a , Jonathan Fortman BS a , Kevin Lunney MD b , Gregory W. Hendey MD b , Robert M. Rodriguez MD a a Department of Emergency Medicine, UCSF School of Medicine, San Francisco General Hospital, San Francisco, CA b Department of Emergency Medicine, UCSF School of Medicine-Fresno, Community Regional Medical Center, Fresno, CA abstract article info Article history: Received 28 March 2013 Accepted 21 April 2013 Background: Computed tomography (CT) has been shown to detect more injuries than plain radiography in patients with blunt trauma, but it is unclear whether these injuries are clinically significant. Study Objectives: This study aimed to determine the proportion of patients with normal chest x-ray (CXR) result and injury seen on CT and abnormal initial CXR result and no injury on CT and to characterize the clinical significance of injuries seen on CT as determined by a trauma expert panel. Methods: Patients with blunt trauma older than 14 years who received emergency department chest imaging as part of their evaluation at 2 urban level I trauma centers were enrolled. An expert trauma panel a priori classified thoracic injuries and subsequent interventions as major, minor, or no clinical significance. Results: Of 3639 participants, 2848 (78.3%) had CXR alone and 791 (21.7%) had CXR and chest CT. Of 589 patients who had chest CT after a normal CXR result, 483 (82.0% [95% confidence interval [CI], 78.7-84.9%]) had normal CT results, and 106 (18.0% [95% CI, 15.1%-21.3%]) had CTs diagnosing injuries—primarily rib fractures, pulmonary contusion, and incidental pneumothorax. Twelve patients had injuries classified as clinically major (2.0% [95% CI, 1.2%-3.5%]), 78 were clinically minor (13.2% [95% CI, 10.7%-16.2%]), and 16 were clinically insignificant (2.7% (95% CI, 1.7%-4.4%]). Of 202 patients with CXRs suggesting injury, 177 (87.6% [95% CI, 82.4%-91.5%]) had chest CTs confirming injury and 25 (12.4% [95% CI, 8.5%-17.6%]) had no injury on CT. Conclusion: Chest CT after a normal CXR result in patients with blunt trauma detects injuries, but most do not lead to changes in patient management. © 2013 Elsevier Inc. All rights reserved. 1. Introduction The prevalence of life-threatening injury-related conditions has remained relatively constant, yet the use of computed tomography (CT) for trauma evaluation has increased dramatically in the past 15 years [1]. The desire to detect injuries with a near-zero miss rate and the widespread availability of rapid CT have driven this multifold increase in CT use and led many trauma centers to the adoption of complete head-to-pelvis CT scanning protocols for blunt trauma evaluation. Proponents of this “pan-scan” approach cite high sensitivity for radiologic injury diagnosis in blunt trauma of the head and cervical spine, whereas other investigators have shown that this can be a low-yield practice clinically in terms of actual patient care. Few of the injuries detected by CT change patient management and the clinical significance of these injuries may not warrant the risks and costs associated with CT [1,2]. The clinical benefit of CT for blunt trauma, then, remains uncertain. At least 3 major problems may be associated with the incremental use of CT in trauma. First, the exposure of potentially harmful ionizing radiation to a disproportionately young patient population may have a true effect on cancer induction risk. Chest CT is among the top 3 types of imaging in terms of this overall risk [3]. Although few physicians recognize the risks of CT-related radiation, recent investigation has determined that it is real and quantifiable [4-7,3]. As many as 2% of cancers in the United States may be attributed to CT radiation, and 29 000 future cancers may result from CT scans performed in the year 2007 alone [4-6,3]. Second, CT American Journal of Emergency Medicine 31 (2013) 1268–1273 ☆ This manuscript has been presented at the American College of Emergency Physicians Annual Symposium in San Francisco on October 15, 2011. ☆☆ Awards: 2011 American College of Emergency Physicians Resident Research Award. ★ Conflicts of interest and source of funding: This publication was supported by the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health, through UCSF-CTSI Grant Number UL1 RR024131. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH. ⁎ Corresponding author. Department of Emergency Medicine, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Dr, MC:CR114, Portland, OR 97239. Tel.: +1 503 494 4430(w), +1 650 353 6669(c); fax: +1 503 494 4997. E-mail addresses: borykea@gmail.com (B. Kea), ruwangamage@gmail.com (R. Gamarallage), hemavairamuthu@yahoo.com (H. Vairamuthu,), Jonathan.Fortman@emergency.ucsf.edu (J. Fortman), KLunney@fresno.ucsf.edu (K. Lunney), GHendey@fresno.ucsf.edu (G.W. Hendey), Robert.Rodriguez@emergency.ucsf.edu (R.M. Rodriguez). 1 Current affiliation: Department of Emergency Medicine, Oregon Health and Sciences University, Portland, OR. 0735-6757/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajem.2013.04.021 Contents lists available at SciVerse ScienceDirect American Journal of Emergency Medicine journal homepage: www.elsevier.com/locate/ajem