As EDs have evolved to handle the increasing volume and complexity of patients requiring immediate care, so too, has the field of emergency radiology. Many EDs across the country now have multiple advanced imaging modalities available 24 hours a day, including Xray, computed tomography (CT), ultrasound, and magnetic resonance imaging (MRI). While many emergency medicine physicians are now trained in performing and evaluating ultrasound images—similar to X-rays in the past—most are less comfortable with CT and MRI.
Emergency radiology, now a recognized subspecialty of diagnostic imaging, has proliferated to meet the demands for immediate interpretation of these images. This combination of around-the-clock access to equipment and expertise has brought cutting-edge, advanced imaging to the front lines of emergency care. In this special feature, we invited a group of emergency radiologists and an expert in cardiovascular imaging to discuss the applicability and utility of several of these techniques in the ED setting.
As illustrated by this panel, advanced imaging has become increasingly valuable and available in providing care to ED patients. In this presentation, however, you will notice the conspicuous absence of specific techniques that are utilized in diagnosis and evaluation of stroke, head/spine trauma, and other neurologic conditions that are commonplace in the ED. Advanced imaging has become critical in these instances and will be discussed in a future article.
Dr Hentel is an associate professor of clinical radiology at Weill Cornell Medical College in New York City. He is also chief of emergency/musculoskeletal imaging and the executive vice-chairman for the department of radiology at New York-Presbyterian Hospital/Weill Cornell Medical Center. He is a member of the EMER GENCY MEDICINE editorial board.
Faster than FAST: Single Pass Whole-Body Computed Tomography for Rapid Evaluation of Trauma Patients
Ashwin Asrani, MD
Dr Asrani is an assistant professor of radiology at Weill Cornell Medical College in New York City and an
assistant attending radiologist at New York-Presbyterian Hospital/Weill Cornell Medical Center in New York City.
Case. A 48-year-old construction worker presented to the ED after he was struck in the right lower chest by a spinning metal drill at a pressure of 1000 psi (torque). Although a focused abdominal sonography for trauma scan was negative, contrast-enhanced computed tomography revealed a large complex liver laceration (red oval, Figure) in the right lobe and a right adrenal hematoma (yellow arrow, Figure).
As part of initial assessment and resuscitation in the ED, severely injured trauma patients frequently undergo a bedside focused abdominal sonography for trauma (FAST) scan to assess for intraperitoneal hemorrhage from an underlying major abdominal visceral injury, as well as the presence of pleural and/or pericardial effusion. However, the use and role of a FAST scan in hemodynamically stable patients has recently been questioned since, based on its relatively low sensitivity for visceral injury, many of these cases eventually require computed tomography (CT) (See Case). In addition, patients in this subset with a positive FAST scan frequently have subsequent CT to further assist clinicians in understanding the nature of injury and to guide management recommendations (eg, operative versus nonoperative options).1
Advances in the speed of CT have made it possible to obtain images of the entire body with only a single dose of contrast injection. The elimination of segmental acquisition of torso images (eg, head, neck, chest, abdomen) eliminates the need to reposition the patient, repeat scout images, and postpone the reconstruction of reformats and other special views until the end of the examination. Depending on the original protocol, this in turn minimizes patient time in the CT-scan room by approximately 31% to 42%,2,3 and significantly reduces radiation exposure by 17% compared to conventional segmental acquisition of different body parts.2
Evidence suggests that direct single-pass whole-body CT improves outcomes in both hemodynamically stable and unstable patients and can reveal significant findings not apparent on initial clinical examination.4,5 Whole-body CT increases injury severity by detecting lesions that would not otherwise have been detected by conventional methods. While this information does not affect treatment options, it does artificially lower the ratio of observed-to-expected deaths.6 The Randomized Study of Early Assessment by CT Scanning in Trauma Patients (REACT-2), a recent international multicenter randomized clinical trial, is expected to provide evidence supporting the value of immediate total-body CT scanning during the primary evaluation of severely injured trauma patients; the results of this trial should become available in 2014.7
As EDs install and upgrade to newer multidetector CT scanners, single-pass whole-body scanning has the potential to save time in situations when it really matters.
References
1. Natarajan B, Gupta PK, Cemaj S, Sorensen M, Hatzoudis GI, Forse RA. FAST scan: Is it worth doing in hemodynamically stable blunt trauma patients? Surgery. 2010;148(4):695-700; discussion 700-701.