Comparing Ultrasound, Chest X-Ray, and CT Scan for Pneumonia Detection

Background: The clinical methods of diagnosing pneumonia have been for many years chest X-rays (CXR) and computed tomography (CT) scans. However, a relatively new modality that is promising, efficient, and cheap is the lung ultrasound (LUS). The scope of this systematic review focuses on evaluating the diagnostic performance of LUS, CXR, and CT for diagnosing pneumonia. Objective: The first aim of this review is to assess the diagnostic accuracy of lung ultrasound in comparison with chest X-rays and CT scans. Methods: PubMed, Cochrane, Embase, and Scopus were electronically searched without date and language limitations were set. Inclusion criteria covered only those diagnostic studies that involved comparing lung ultrasound, chest X-ray, and CT scans in human beings with suspected pneumonia. Both abstraction and quality of studies were assessed by two researchers and the quality was assessed using PRISMA and QUADAS-2 checklists. Results: There were 13 empirical studies included in the review which referred to different patients and contexts. Although none of the imaging techniques could achieve both high sensitivity and high specificity, CT scans produced the highest sensitivity, with values higher than 95% on all occasions, and specificities ranging between 80% and 90%. Lung US was most helpful in pediatric and acute care populations, whereas CT was preferred when there was uncertainty regarding the presentation. Conclusion: Lung ultrasound is a very sensitive, specific, practical method of subsequent lung examination; it is useful in environments that need fast bedside assessment and for patients particularly vulnerable to radiation exposure, such as children. Even though chest X-ray remains valuable in excluding pneumonia in outpatient practices, it lacks sensitivity and is therefore less useful in diagnosing early disease. Computed tomography scans are the most accurate type of scans but should only be used in the more severe interventions due to cost and radiation exposure.