SAN DIEGO— Although the use of X-rays as a diagnostic tool has been around since 1895, being able to rapidly and accurately read radiographic images remains a mainstay tool in the emergency physician’s diagnostic toolbox, said Daniel Kim, MD, FRCPC, ultrasound fellowship director at the University of British Columbia and attending emergency physician at Vancouver General Hospital, both in Vancouver. During his morning presentation at ACEP18, Dr. Kim framed the use of X-rays as a way to not only be the basis of an initial differential suspicion, but as a gateway to definitive imaging procedures such as ultrasound and CT.
Dr. Kim used a series of case studies to provide five tips for interpreting X-rays. To begin, the emergency physician should always read their own films. A radiologist’s interpretation can be significantly delayed when time is critical to patient outcome. Moreover, integrating patient history and physical findings with the X-ray can better situate the diagnosis. A case of pneumomediastinum in a young male complaining of pleuritic chest pain was used to illuminate this point. The initial impression by the radiologist revealed an unremarkable assessment. However, a closer inspection revealed the presence of the free air along the left heart border.
Emergency physicians should compare the new film to old X-rays whenever possible. A 56-year-old female with shortness of breath had clear breath sounds, which seemed inconsistent with her past history of asthma. A comparison of a previous recent X-ray indicated a new onset of cardiomegaly. Follow up with ultrasound indicated a pericardial effusion.
Next, it’s essential to know normal X-ray anatomy. Dr. Kim used a case of a middle-aged male experiencing chest pain, with a widened mediastinum found on X-ray to suspect an aortic dissection that was confirmed with ultrasound. A widened mediastinum is a radiographic finding that can be caused by a myriad of conditions, including aortic aneurysm, aortic dissection, esophageal rupture, cardiac tamponade, and pericardial effusion.
As common as X-rays are, it’s essential to know their limitations. A case study in necrotizing fasciitis illuminated the fact that a CT scan is more sensitive (89 percent) in detecting this potentially life-threatening condition as compared to an X-ray (49 percent).
Finally, acquiring at least two views of the area in question is vital. Dr. Kim showed a single, fairly unremarkable anterior view of the shoulder joint for a patient who woke up with pain in the area. However, the second image revealed a posterior dislocation, which is rare compared to anterior dislocations. If the diagnosis is uncertain, ordering a CT will be needed to confirm the suspicion.
“At the end of the day, practice, practice, practice is really the best way” to hone one’s skill in reading X-ray film, concluded Dr. Kim. There are many resources on the web and in print to help refine this valuable skill.