Emergency (****); * (*): *-* This open-access article distributed under the terms of the Creative Commons Attribution Noncommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com 184 Emergency (2016); 4 (4): 184-187 ORIGINAL ARTICLE The Accuracy of Plain Radiography in Detection of Traumatic Intrathoracic Injuries Maryam Abedi Khorasgani1, Ali Shahrami1, Majid Shojaee1, Hossein Alimohammadi1, Afshin Amini1, Hamid Reza Hatamabadi2* 1- Emergency Department, Imam Hossein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2- Safety promotion and injury prevention research center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. *Corresponding Author: Hamidreza Hatamabadi, Department of Emergency Medicine, Imam Hossein Hospital, Shahid Madani Avenue, Tehran, Iran. Tel: +989123861683; Email: hhatamabadi@yahoo.com. Received: July 2015; Accepted: September 2015 Abstract Introduction: Rapid diagnosis of traumatic intrathoracic injuries leads to improvement in patient management. This study was designed to evaluate the diagnostic value of chest radiography (CXR) in comparison to chest com- puted tomography (CT) scan in diagnosis of traumatic intrathoracic injuries. Methods: Participants of this pro- spective diagnostic accuracy study included multiple trauma patients over 15 years old with stable vital admitted to emergency department (ED) during one year. The correlation of CXR and CT scan findings in diagnosis of trau- matic intrathoracic injuries was evaluated using SPSS 20. Screening characteristics of CXR were calculated with 95% CI. Results: 353 patients with the mean age of 35.2 ± 15.8 were evaluated (78.8% male). Age 16-30 years with 121 (34.2%), motorcycle riders with 104 (29.5%) cases and ISS < 12 with 185 (52.4%) had the highest frequency among patients. Generally, screening performance characteristics of chest in diagnosis of chest traumatic injuries were as follows: sensitivity 50.3 (95% CI: 44.8 – 55.5), specificity 98.9 (95% CI: 99.5 – 99.8), PPV 97.8 (95% CI: 91.5 – 99.6), NPV 66.4 (95% CI: 60.2 – 72.03), PLR 44.5 (95% CI: 11.3 175.3), and NLR 0.5 (95% CI: 0.4 – 0.6). Accuracy of CXR in diagnosis of traumatic intrathoracic injuries was 74.5 (95% CI: 69.6 – 78.9) and its area under the ROC curve was 74.6 (95% CI: 69.3 – 79.8). Conclusion: The screening performance characteristics of CXR in diagnosis of traumatic intrathoracic injuries were higher than 90% in all pathologies except pneumothorax (50.3%). It seems that this matter has a great impact on the general screening characteristics of the test (74.3% accuracy and 50.3%sensitivity). It seems that, plain CXR should be used as an initial screening tool more carefully. Keywords: X-Rays; radiography, thoracic; tomography, X-ray computed; diagnostic techniques and procedures; thoracic injuries Cite this article as: Abedi Khorasgani M, Shahrami A, Shojaee M, Alimohammadi H, Amini A, Hatamabadi H. The accuracy of plain radiography in detection of traumatic intrathoracic injuries. Emergency. 2016;4(4):184-187 Introduction: rauma is considered one of the major causes of mortality and permanent disability and the 4th cause of death behind cardiovascular diseases, cancer, and stroke (1, 2). Based on the statistics reported by the Iranian legal medicine organization, trauma and its consequences are the most common cause of mortal- ity in Iran, as 75.9% and 74.1% of deaths were trauma related in 2003 and 2004, respectively (3). Among inju- ries due to trauma, chest trauma is responsible for 25% of deaths due to trauma and 50% of trauma-related deaths (4, 5). Diagnostic and treatment approaches may vary depending on the equipment of the center and the physician’s decision. Physical examination and chest ra- diography (CXR) are the first steps in diagnosis and treatment of multiple trauma patients. Accuracy of the diagnoses are widely dependent on the type of injury, time of arrival, and the method of diagnosis used (6). During the past decade, imaging diagnostic methods have improved and therefore, accuracy of pulmonary contusion, hemothorax, and pneumothorax diagnosis has increased. Yet, these methods do not have high spec- ificity in ruling out chest and abdominal injuries (6). Chest computed tomography (CT) scan as the gold stand- ard, can diagnose pulmonary contusion, hemothorax, pneumothorax, and rib fracture with high sensitivity (7). Rapid diagnosis of pneumothorax in patients with trau- matic injuries, has led to improvement in patient man- agement. Sensitivity of CT scan compared to CXR, is 100% compared to 42% in this regard (8-11). Yet, CXR is T This open-access article distributed under the terms of the Creative Commons Attribution Noncommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com 185 Emergency (2016); 4 (4): 184-187 still considered a useful and non-expensive method providing valuable information in the initial evaluation of trauma patients (9, 12). Considering global and na- tional statistics on trauma, especially chest trauma and its high prevalence in the youth population, this study was designed to evaluate the diagnostic value of CXR in comparison to chest CT scan in diagnosis of traumatic in- trathoracic injuries. Methods: In the present prospective diagnostic accuracy study, the value of CXR for diagnosis of traumatic intrathoracic in- juries was evaluated in comparison to CT scan. The par- ticipants of this study included multiple trauma patients admitted to emergency department (ED) of Imam Hos- sein Hospital, Tehran, Iran, during March 2014 to Febru- ary 2015. Multiple trauma patients over 15 years old with stable vital signs and those who had requests for both plain CXR and CT scan of chest were enrolled. Ex- clusion criteria consisted of unstable vital signs, pene- trating trauma, pregnancy, and not undergoing CXR or chest CT scan. Demographic data of the patients, trauma mechanism and severity of injury based on injury sever- ity score (ISS), and CXR and CT scan findings regarding presence of hemothorax, pneumothorax, pulmonary contusion, and fracture of rib, spine, and sternum were recorded in a checklist. Finally, the correlation of CXR and CT scan findings in diagnosis of chest traumatic in- juries was evaluated. Physical examination, history, and data gathering for all patients was done by an emergency medicine resident in charge of trauma unit. Since the ac- curacy of CXR interpretation has been proved to be high for emergency medicine specialists (13), interpretation of CXR was done by a senior emergency medicine resi- dent who was blind to the patients’ clinical conditions. Chest CT scans were also reported by a radiologist blind to the clinical condition of the patients. Based on the Hel- sinki Declaration, patient data were kept confidential. None of the patients underwent CXR outside the treat- ment process and CT scan indications were determined based on the advanced trauma life support (ATLS) guide- lines or the decision of in charge surgeon. Chest CT scan was considered the gold standard. All CXRs were per- formed as posterior-anterior while the patient was in upright position. Statistical analysis: Sample size was calculated to be 87 cases considering 65% sensitivity of CXR in diagnosis of intrathoracic inju- ries, 10% desired precision, and 95% confidence inter- val (CI). SPSS 20 was used to analyze data. Correlation of two studied imaging was calculated using Spearman's rank correlation coefficient. Quantitative variables were reported as mean and standard deviation (SD) and qual- itative ones as frequency and percentage. Sensitivity, specificity, positive and negative predictive value (PPV and NPV) and positive and negative likelihood ratio (PLR and NLR) of CXR in comparison with CT scan were calcu- lated with 95% CI. Finally, area under the receiver oper- ating characteristic (ROC) curve of CXR was calculated. Results: 353 patients with the mean age of 35.2 ± 15.8 were eval- Table 1: Baseline characteristics of the studied patients Variables Frequency (%) Age (years) 16-30 121 (34.28) 31-45 99 (28.05) 46-60 83 (23.51) > 61 50 (14.16) Sex Male 278 (78.8) Female 75 (21.2) Trauma mechanism Car passenger 102 (28.9) Motorcycle rider 104 (29.5) Pedestrian 90 (25.5) Bicycle rider 3 (0.8) Car rollover 25 (7.1) Crush 5 (1.4) Falling from > 3m 24 (6.8) Injury severity* < 12 185 (52.4) ≥ 12 168 (47.6) * Based on injury severity score (ISS). Table 2: Screening performance characteristics of Chest X-ray in detection of traumatic intra-thoracic injuries Characteristics Type of injury (95% Confidence Interval) Pneumothorax Hemothorax Contusion Sensitivity 45 (32.1-58.4) 99 (97.2-99.8) 98.9 (96.8-99.8) Specificity 98.6 (96.5-99.6) 29.8 (17.3-44.9) 7.59 (2.84-15.8) PPV1 89.8 (85.9-92.8) 90.2 (86.5-93.1) 88.8 (74.1-83) NPV2 87.1 (70.2-96.4) 82.4 (56.6-96.2) 66.7 (29.9-92.5) PLR3 1.7 (1.43-2.26) 1.4 (1.17-1.7) 1.07 (1-1.14) NLR4 0.03 (0.11-0.83) 0.03 (0.009-0.11) 0.14 (0.036-0.56) 1. Positive predictive value; 2. Negative predictive value; 3. Positive likelihood ratio; 4. Negative likelihood ratio. This open-access article distributed under the terms of the Creative Commons Attribution Noncommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com Abedi Khorasgani et al 186 uated (78.8% male). Table 1 shows the baseline charac- teristics of the patients. Age 16-30 years with 121 (34.2%), motorcycle riders with 104 (29.5%) cases and ISS < 12 with 185 (52.4%) had the highest frequency among patients. There was a significant correlation be- tween the findings of two studied modalities (ρ = 0.68; p < 0.001). Screening characteristics of plain CXR in diag- nosis of various traumatic intrathoracic injuries and fractures are presented in tables 2 and 3, respectively. Generally, screening performance characteristics of chest in diagnosis of chest traumatic injuries were as fol- lows: sensitivity 50.3 (95% CI: 44.8 – 55.5), specificity 98.9 (95% CI: 99.5 – 99.8), PPV 97.8 (95% CI: 91.5 – 99.6), NPV 66.4 (95% CI: 60.2 – 72.03), PLR 44.5 (95% CI: 11.3 175.3), and NLR 0.5 (95% CI: 0.4 – 0.6). Accuracy of CXR in diagnosis of traumatic intrathoracic injuries was 74.5 (95% CI: 69.6 – 78.9) and its area under the ROC curve was 74.6 (95% CI: 69.3 – 79.8) (figure 1). Discussion: Based on the findings of the present study, CXR has low sensitivity in diagnosing traumatic intrathoracic injuries compared to CT scan. While its specificity and PLR is high and close to that of CT scan. Carrying out physical examination and plain CXR are considered as the first step in diagnosing traumatic chest injuries. El Wakeel et al. in the study of 100 blunt chest trauma patients showed the higher sensitivity of CT scan compared to CXR in detection of intrathoracic injuries (7). As shown in table 2 and 3, the screening characteris- tics of CXR are higher than 90% in all pathologies except pneumothorax. It seems that this matter has a great im- pact on the general screening characteristics of the test. The pneumothorax cases, which were missed with CXR and diagnosed by CT scan are frequent and named occult pneumothorax, which usually are benign in nature. In a study, Eckstein et al. estimated the sensitivity of CXR to be 42% in diagnosis of pneumothorax (10). Diagnosis of hemothorax in CXR is difficult due to different reasons such as: the patient not being able to sit up, poor quality of the radiography, and improper preparation before ra- diography (being in sitting or upright position for at least 15 minutes before radiography performance). In the present study, sensitivity and specificity of CXR in diag- nosis of pulmonary contusion were estimated to be 98.9 and 7.59%, respectively. These measures were 40 and 100%, respectively in the Eckstein study (10). Chest CT scan as the gold standard can diagnose pulmo- nary contusion, hemothorax, pneumothorax, and rib fracture with high sensitivity (8-12). Despite the effi- ciency and high diagnostic value of CT scan in trauma pa- tients, few evidence based indications exist for using this method for all patients. Therefore, using it as a routine screening method is still a matter of debate (10). Char- doli et al. believed that use of chest CT scan as an initial screening tool in trauma patients with stable hemody- namics can change the patient management and out- come (14). Although CT scan can be very useful for eval- uation of chest trauma patients, especially those with lung parenchyma injuries, hemothorax, and pneumotho- rax, the nephrotoxicity due to contrast material, cumula- tive dose of radiation, and the high cost of CT scan are problems that cannot be overlooked (6). On the other hand, performing plain CXR and then CT scan to confirm the results doubles the problem. Therefore, a decision on whether all chest trauma patients with stable hemody- namics should undergo CT scan from the start cannot be made yet. It seems that making a decision based on a combination of physical examination, history, trauma mechanism, as well as imaging can be very helpful in this Table 3: Screening performance characteristics of Chest X-ray in detection of traumatic thoracic fractures Characteristics Type of fracture (95% confidence interval) Rib Sternal Vertebral Sensitivity 98.9 (3.3-20.7) 99.7 (98.4-100) 100 (98.9-100) Specificity 57 (45.3-68.1) 40 (5.2-85.3) 22.7 (7.8-45.4) PPV1 88.9 (84.8-92.2) 99.1 (97.5-99.8) 95.1 (92.3-97.1) NPV2 93.8 (82.8-98.7) 66.7 (9.4-99.2) 100 (47.8-100) PLR3 2.3 (1.78-2.26) 1.6 (0.8-3.4) 1.29 (1.03-1.62) NLR4 0.019 (0.006-0.06) 0.007 (0-0.06) 0 (0-0) 1. Positive predictive value; 2. Negative predictive value; 3. Positive likelihood ratio; 4. Negative likelihood ratio. Figure 1: Receiver operating characteristics (ROC) curve of chest X-ray in comparison with computed tomography scan 0 .0 0 0 .2 5 0 .5 0 0 .7 5 1 .0 0 S e n s it iv it y 0.00 0.25 0.50 0.75 1.00 1 - Specificity Area under ROC curve = 0.7457 This open-access article distributed under the terms of the Creative Commons Attribution Noncommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com 187 Emergency (2016); 4 (4): 184-187 regard. The new methods suggested for chest trauma evaluation, tend to use scoring systems and clinical deci- sion rules to some extent (15, 16). It seems that routine use of CXR based on ATLS protocol for all multiple trauma patients is questionable. In this regard, new clin- ical decision rules similar to NEXUS (16) and TIRC (15) that have been designed for clinical triage of patients in need for chest imaging, can be implemented after valida- tion studies. Conclusion: Based on the findings of the present study, the screening performance characteristics of CXR in diagnosis of trau- matic intrathoracic injuries were higher than 90% in all pathologies except pneumothorax. It seems that this matter has a great impact on the general screening char- acteristics of the test (74.3% accuracy and 50.3%sensi- tivity). It seems that, plain CXR should be used as an ini- tial screening tool for all the chest trauma patients more carefully. Acknowledgment: The authors would like to thank all the staff of Trauma Unit of Imam Hossein Hospital that helped carry out this study. This article is extracted from the thesis of Dr. Abedi Khorasgani to earn her specialist degree in emer- gency medicine, registered under the number 312 in the research and technology department of Shahid Beheshti University of Medical Sciences. 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