Advertisement
Improving CT Safety

Improving CT Safety

CT is a powerful diagnostic technology, but it is also associated with risks. Ionizing radiation can damage cells and act as a weak carcinogen. The challenge is to find the optimal x-ray dose for each CT exam. “About 80 million CTs are performed each year in the United States,” says John M. Boone, PhD. “The higher the dose, the better the images, but we also want the lowest possible dose so that patients are protected from unnecessary radiation exposure. The key is to find the balance between acceptable image quality and acceptable doses.” New Strategies The Journal of the American College of Radiology (JACR) recently devoted an entire issue to CT safety. Dr. Boone and other specialists from the University of California, Davis contributed three studies to the special issue. In one of the JACR papers, the need to improve dose calculations was discussed. Manufacturers use phantoms along with instruments to measure radiation, but different companies use phantoms of different sizes, making comparisons problematic in some cases. To prevent these problems, a new metric, the size-specific dose estimate (SSDE), is recommended. “SSDEs can provide a better way to estimate patient doses and can help compare scanners from different companies,” says Dr. Boone. SSDEs may also address the need to more accurately estimate CT doses from a range of patient sizes, especially in pediatric patients. The second JACR paper addressed the challenges of optimizing different CT machines. Automatic exposure protocols must be set up, but this can vary doses based on tissue thickness. “Transferring these settings between machines can be difficult and time consuming,” Dr. Boone says. To overcome this...
Safety of Contrast Agents in the Critically Ill

Safety of Contrast Agents in the Critically Ill

Ultrasound contrast agent safety in critically ill patients undergoing echocardiography has been questioned by the FDA. This controversy was the result of rare reports showing that deaths or life-threatening adverse reactions occurred in close proximity to the administration of ultrasound contrast agents. “Since these reports surfaced around 2007, many studies have been conducted to better define the safety profile of these agents,” says Michael L. Main, MD. An Observational Analysis In a large observational study published in JACC: Cardiovascular Imaging, Dr. Main and colleagues compared 48-hour all-cause mortalities and hospital stay mortalities among critically ill patients who underwent echocardiography either with or without an ultrasound contrast agent. Data were collected on more than a million participants through discharge information from a database that included information on primary and secondary diagnoses, procedure billing codes, and demographic and baseline patient information in addition to hospital characteristics. At discharge, more than 990,000 patients underwent echocardiography without a contrast agent, whereas 16,222 received a contrast agent for their exam. According to the results, ultrasound contrast agent use was associated with a 28% lower mortality rate at 48 hours among critically ill patients undergoing echocardiography when compared with no ultrasound contrast agent use. Recipients of ultrasound contrast agents also had significantly lower mortality rates over their entire hospital stay when compared with those who did not receive one (14.85% vs 15.66%). “Importantly, our findings were consistent across a wide variety of major comorbidities and important demographic subgroups, such as age and gender,” says Dr. Main. Overall, there were no groups with significantly greater odds for mortality after receiving a contrast agent. Impactful Findings Data...
Managing Children With Low-Risk Blunt Abdominal Trauma

Managing Children With Low-Risk Blunt Abdominal Trauma

Intra-abdominal injuries resulting from blunt torso trauma are a leading cause of morbidity in children and account for a significant number of ED admissions each year. Identifying these injuries early is critical to reducing morbidity and mortality from delayed or missed diagnoses. In recent years, CT has become standard for diagnosing many traumatic injuries, including those within the abdomen. At the same time, however, CT use in trauma and emergency care has expanded much faster than evidence for its use. “CT provides detailed and useful information about injuries and helps clinicians make informed management decisions,” explains James F. Holmes, MD, MPH, “but it also has its drawbacks. It exposes patients to relatively large radiation dosages, putting them at risk for radiation-induced malignancies.” Testing a Prediction Rule on Blunt Torso Trauma Recently, several smaller investigations have suggested that children with blunt torso trauma can be stratified by risk for intra-abdominal injury using a combination of readily accessible clinical factors. These studies, however, have been limited by their retrospective or single-center study designs and small samples. In an effort to overcome these limitations, Dr. Holmes and colleagues had a study published in Annals of Emergency Medicine that aimed to derive a prediction rule that identifies children with blunt torso trauma for whom CT would generally not be indicated. More than 12,000 children (average age, 11.1 years) from 20 EDs with blunt torso trauma were enrolled in the prospective analysis by Dr. Holmes’s study team. A prediction rule was created using a seven-item checklist that included patient history and physical examination variables readily available without the need for using laboratory or ultrasound...

Imaging Use & Atraumatic Headache in the ED

Atraumatic headache is one of the most common complaints in EDs, but only a small subset of patients who present to the ED with this complaint are found to have life-threatening intracranial pathology (ICP) upon imaging. Additionally, imaging guidelines for these patients remain unclear. As a result, emergency physicians face a serious diagnostic dilemma when managing atraumatic headache, says John W. Gilbert, MD. “Imaging infrequently reveals significant findings, but results from these tests nevertheless have the potential to detect life-threatening pathology.” [polldaddy poll=6862787] Several studies have demonstrated that overall use of diagnostic imaging in the ED is increasing. The causes are thought to be multifactorial, ranging from medicolegal concerns and patient demand to the availability of diagnostic scanners that operate at ever-faster rates. This has the potential to lead to imaging overutilization with little benefit and may potentially harm patients. In clinical studies, increased use of imaging has been associated with higher costs, longer patient wait times, greater exposure to ionizing radiation, and decreased ED flow and efficiency. “In the absence of clear evidence-based guidelines and given the potential consequences of misdiagnosis, many physicians understandably struggle when deciding whether to pursue further workup,” explains Dr. Gilbert. “In some cases, they may err on the side of increased testing. It’s important for physicians to be aware of recent trends in imaging utilization, particularly when there’s a sharp increase without obvious corresponding evidence of benefit. This information can help guide efforts toward better defining imaging criteria so that diagnostics are used appropriately.” Imaging & Diagnostics in Atraumatic Headache In the July 2012 Emergency Medicine Journal, Dr. Gilbert and colleagues had a...
[ HIDE/SHOW ]