Archives of Academic Emergency Medicine. 2019; 7 (1): e8 OR I G I N A L RE S E A RC H Comparing Sensitivity of Ultrasonography and Plain Chest Radiography in Detection of Pneumonia; a Diagnos- tic Value Study Ebrahim Karimi1∗ 1. Emergency Department, Be’sat Hospital, AJA University of Medical Sciences, Tehran, Iran. Received: October 2018; Accepted: December 2018; Published online: 22 January 2019 Abstract: Introduction: Rapid detection of pneumonia and early initiation of antibiotic therapy are associated with better prognosis in patients. The present study was designed aiming to evaluate the sensitivity of chest ultrasonog- raphy performed by emergency medicine specialists in detection of pneumonia and comparing it with plain radiography. Methods: In the present diagnostic accuracy study, patients presenting to the emergency depart- ment with clinical symptoms of lung infection underwent plain radiography, ultrasonography, and computed tomography (CT) scan of chest and the screening performance characteristics of plain radiography and ultra- sonography were compared considering CT scan findings as the gold standard. Results: 280 patients with the mean age of 56.47 ± 19.79 (10 – 92) years were studied (57.1% male). The results of chest CT scan were indicative of infection symptoms being present and confirmed pneumonia diagnosis for all the patients. Out of the 280 cases of pneumonia confirmed via chest CT scan, 17 (6.1%) cases were not detected via ultrasonography and 48 (17.1%) cases were missed by chest radiography (false negative cases). No false positive case was reported by ultrasonography or chest x-ray. Since all of the CT scans were positive, no comment can be made regarding the specificity of the evaluated tests, but sensitivity of ultrasonography and plain radiography were 93.92 (90.28 – 96.31) and 82.85 (77.81 – 86.97), respectively (p = 0.583). Conclusion: Based on the findings of the present study, although the sensitivity of ultrasonography in detection of pneumonia was significantly higher than chest x-ray, overall the screening performance characteristics of the 2 tests were not significantly different. Therefore, considering characteristics such as safety, low cost, being portable, and being available, ultrasonography seems to be a reasonable tool for screening and diagnosis of patients with pneumonia. Keywords: Diagnostic imaging; ultrasonography; sensitivity and specificity; radiography, thoracic; tomography, x-ray computed Cite this article as: Karimi E. Comparing Sensitivity of Ultrasonography and Plain Chest Radiography in Detection of Pneumonia; a Diagnos- tic Value Study. Arch Acad Emerg Med. 2019; 7(1): e8. 1. Introduction Pneumonia is a common cause of emergency department (ED) visits and has been reported to be responsible for 1 million hospitalizations annually (1). Patients usually present with cough, tiredness, fever, shortness of breath, and pleuritic chest pain in typical cases. Diagnosis of pneumonia is usually done in ED and if it is not detected it will be asso- ciated with a high risk of complications and mortality. Rapid diagnosis of pneumonia and early treatment with antibiotic ∗Corresponding Author: Ebrahim Karimi; Emergency Department, Be’sat Hospital, Afsariyeh Avenue, Basij Highway, Tehran Iran. Tel: +989124544838 Email: ebrahimkarimi86@gmail.com are factors that have been associated with better prognosis and outcome (2, 3). History taking and clinical examination are the basis of diagnosing this disease and there are positive findings in history and clinical examination of these patients, including rales, rhonchi, wheezing, bronchial respiratory sounds, reduction of respiratory sounds, and dullness to percussion in chest (4). Confirmation of diagnosis for this disease depends on imaging. Sensitivity of plain chest radiography in detection of pneumonia has been reported as 38% to 76% in studies (5-8). Although chest computed tomography (CT) scan is considered the standard in detection of pneumonia, it is associated with disadvantages such as unavailability and high exposure to radiation (9, 10). Currently, chest ultra- sonography is very popular for detection of pulmonary This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem E. Karimi et al. 2 diseases such as pneumothorax, pulmonary edema, pleural effusion and pneumonia as a cheap, available, safe, and portable tool (11). Sensitivity of ultrasonography compared to radiography has been reported to be between 80% and 90% in detection of pneumonia (8, 12, 13). With the intro- duction of emergency medicine discipline in Iran, all the teaching wards have been provided with ultrasound devices and emergency medicine specialists have been trained for using this tool. Therefore, the present study was designed aiming to evaluate the sensitivity of chest ultrasonography performed by emergency medicine specialists in detection of pneumonia and comparing it with plain radiography. 2. Methods 2.1. Study design and setting The present diagnostic accuracy study has been performed on patients presenting to the emergency department of Be’sat Hospital, Tehran, Iran, with symptoms of pulmonary infection in the time interval between October 2015 and March 2017. Methodology of the present study was approved by the ethics committee of AJA University of Medical Sci- ences and the researchers adhered to the ethical principles presented in Helsinki declaration and keeping patient data confidential. All the probable costs inflicted on the patients were provided by the research team. 2.2. Participants Adult patients (over 18 years of age) presenting to the men- tioned emergency department with clinical symptoms of pneumonia such as cough, phlegm, shortness of breath, hemoptysis, and temperature higher than 38◦C were studied using non-probability convenience sampling. Pregnant pa- tients, those with immunodeficiency, those consuming corti- costeroids or any other immunosuppressant, those affected with chronic kidney or liver failure, and hemodynamically unstable patients were excluded from the study. No sex limi- tation was applied in the present study. 2.3. Imaging After history taking, accurate clinical examination, evalua- tion of vital signs, dismissing cardiac causes for shortness of breath including heart attack, and providing primary health- care, explanations regarding the aims of the study were given to the patients or their relatives. Then chest ultra- sonography was performed on participants by trained emer- gency medicine residents under supervision of the in charge attending emergency medicine specialist. All ultrasounds were performed with Samsung HM70A device using a curved probe with 3.5 – 5 MHz frequency for observing the pul- monary and pleural parenchyma and 7.5 – 10 MHz frequency for observing more superficial lesions of the chest. For ultra- sonographic examination of the lungs, each half of the chest was divided into anterior (from the parasternal line to the an- terior auxiliary line), lateral (between the posterior and mid- dle auxiliary lines), and posterior (from the posterior aux- iliary line to the paravertebral line) sections and evaluated separately. The depth of ultrasound field in this study was adjusted between 16 and 18 centimeters. Ultrasonographic symptoms evaluated in this study included air bronchogram, fluid bronchogram, pleural effusion, b lines (comet tail sign), and subpleural consolidation. After the performance of ultrasonography, patients were sent to the imaging unit to undergo plain radiography and chest CT scan. Chest radiographies were performed in standing position from both anterior-posterior and lateral views for all the patients. Helical CT scan was performed on patients without injection of a contrast agent. Interpretation of the chest radiographies and CT scans was done by an emergency medicine specialist and a radiologist, separately, both of whom were blind to the clinical and ultra- sonography findings of the patients. 2.4. Data gathering An emergency medicine specialist was responsible for recording patients’ data. For this purpose, a checklist was filled out for each patient, which consisted of age, sex, chest ultrasound findings, plain chest radiography findings, and chest CT scan findings. 2.5. Statistical Analysis To analyze data, SPSS 20 statistical software was used. Find- ings were reported using mean and standard deviation or fre- quency and percentage indices summarized in tables. To cal- culate screening performance characteristics of ultrasonog- raphy and plain chest x-ray, a medical calculator was used and sensitivity, specificity, positive and negative predictive values (PPV and NPV ), and positive and negative likelihood ratios (PLR and NLR) were reported with 95% confidence in- terval (CI). P values less than 0.05 were considered statisti- cally significant. Table 1: Chest ultrasonography findings of studied patients Signs Frequency (%) Air bronchogram 160(57.1) Fluid bronchogram 118 (42.1) Pleural effusion 143 (51.1) B lines (comet tail sign) 126 (45.0) Subpleural consolidation 62 (22.1) This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem 3 Archives of Academic Emergency Medicine. 2019; 7 (1): e8 Table 2: Screening performance characteristics of chest ultrasonography and radiography in diagnosis of pneumonia Characteristics Ultrasonography Radiography Sensitivity 93.92 (90.28-96.31) 82.85 (77.81-86.97) Specificity NaN NaN PPV 100.00 (98.20- 100.00) 100.00 (97.96- 100.00) NPV 0.00 (0.00-22.92) 0.00 (0.00-20.30) PLR Infinite Infinite NLR Infinite Infinite NaN: the calculation cannot be performed because the values entered include one or more instances of zero. PPV: positive predictive value; NPV: negative predictive value; PLR: positive likelihood ratio; NLR: negative likelihood ratio. 3. Results 280 patients with the mean age of 56.47 ± 19.79 (10 – 92) years were studied (57.1% male). Table 1 shows the chest ultrasonography findings of these patients. In 118 (42.1%) cases, positive ultrasonography findings were on the right, 96 (34.3%) were on the left, and 48 (17.1%) were bilateral. The results of chest CT scan were indicative of infection symptoms being present and pneumonia diagnosis was confirmed for all the patients. Out of the 280 cases of pneu- monia confirmed via chest CT scan, 17 (6.1%) cases were not detected via ultrasonography and 48 (17.1%) cases were missed by chest radiography (false negative cases). No false positive case was reported by ultrasonography or chest x-ray. Table 2 depicts the screening performance characteristics of ultrasonography and plain chest radiography in detection of pneumonia considering chest CT scan as the gold standard. Since all of the CT scans were positive, no comment can be made regarding the specificity of the evaluated tests, but as shown in table 2, sensitivity of ultrasonography in detection of pneumonia was higher than plain radiography, yet this difference was not clinically significant (p = 0.583). 4. Discussion Based on the findings of the present study, although the sen- sitivity of ultrasonography in detection of pneumonia was significantly higher than chest x-ray, overall the screening performance characteristics of the 2 tests were not signifi- cantly different. Therefore, considering characteristics such as safety, low cost, being portable, and being available, ultra- sonography seems to be a reasonable tool for screening and diagnosis of patients with pneumonia. Using lung ultrasonography in evaluation of patients is be- coming more popular in emergency department (14). Al- though old methods are still used for diagnosis, lung ultra- sonography can reduce the diagnostic errors of plain radio- graphy as a helping tool. In addition, ultrasound is a useful device for follow-up of patients with pneumonia. Decrease in air broncogram and the volume of pleural effusion com- pared to the primary ultrasounds can be considered signs of improvement in the patient (15). In children, due to the high risk of cancer in the early years of life in case of being exposed to radiation, ultrasonography can be a better method than CT scan and plain chest radiography for detection of pneu- monia. In children, due to the small body size and small pul- monary mass, echo penetration is higher and a higher vol- ume of the lung can be seen (15). By studying 144 adults, Bourcier et al. reported 95% sensitivity for ultrasonography in detection of pneumonia and introduced it as the first line of diagnosis for these patients (5). In 2012, by studying 362 patients with suspected pneumonia acquired from the society, Reissig et al. reported 93% sensi- tivity for detection of pneumonia and expressed that about 8% of the lesions related with pneumonia are not detectable via ultrasonography and negative results in ultrasonography are not enough for ruling out pneumonia (15). In a brief re- port, Taghizadieh et al. reported the high accuracy of ultra- sonography compared to plain chest radiography in detec- tion of pneumonia (7). Of course, ultrasonography is depen- dent on the individual performing it and emergency physi- cians need to be familiar with the ultrasonographic appear- ance of other differential diagnoses that can lead to consol- idation such as lymphoma and bronchoalveolar carcinoma (16, 17). Overall, like many other diagnostic methods, if ul- trasonography is performed for a suitable person, in proper conditions and by a skillful person, it can play an important role in screening and detection of pneumonia, which lead to rapid initiation of treatment, improving the outcome of pa- tients with pneumonia as a result. Therefore, including ul- trasonography training in detection of pneumonia in emer- gency resident’s course syllabus seems important more than ever. 5. Limitation The present study was done on patients with suspected pneumonia in one center and this limits the generalization of its findings. On the other hand, the dependence of ultra- sonography on the individual performing it should be con- sidered in interpretation and generalization of the data. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem E. Karimi et al. 4 6. Conclusion Based on the findings of the present study, although the sen- sitivity of ultrasonography in detection of pneumonia was significantly higher than chest x-ray, overall the screening performance characteristics of the 2 tests were not signifi- cantly different. Therefore, considering characteristics such as safety, low cost, being portable, and being available, ultra- sonography seems to be a reasonable tool for screening and diagnosis of patients with pneumonia. 7. Appendix 7.1. Acknowledgements All the emergency department staff members who cooper- ated throughout the study are thanked. 7.2. Author contribution The author met the standard criteria for authorship based on the recommendations of the international committee of medical journal editors. Authors’ ORCIDs Ebrahim Karimi: 0000-0002-3542-9099 7.3. Funding/Support No fund has been received. 7.4. Conflict of interest There is none. References 1. Halm EA, Teirstein AS. Management of community- acquired pneumonia. 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