Emergency department imaging: current practice

Early head-to-pelvis computed tomography in out-of-hospital circulatory arrest without obvious etiology

OBJECTIVES

Patients resuscitated from an out-of-hospital circulatory arrest (OHCA) commonly present without an obvious etiology. We assessed the diagnostic capability and safety of early head-to-pelvis computed tomography (CT) imaging in such patients.

METHODS

From November 2015 to February 2018, we enrolled 104 patients resuscitated from OHCA without obvious cause (idiopathic OHCA) to an early sudden-death CT (SDCT) scan protocol within 6 h of hospital arrival. The SDCT protocol included a noncontrast CT head, an electrocardiogram-gated cardiac and thoracic CT angiogram, and a nongated venous-phase abdominopelvic CT angiogram. Patients needing urgent cardiac catheterization or hemodynamically unable to tolerate SDCT were excluded. Cardiac CT analyses were blinded, but other SDCT findings were clinically available. Primary endpoints were the number of OHCA causes identified by SDCT compared to the adjudicated cause and critical diagnoses identified by SDCT, including resuscitation complications. Safety endpoints were acute kidney injury (AKI) and inappropriate treatments based on SDCT findings. Acute coronary syndrome was the presumed etiology if any major coronary artery had a >50% stenosis without another OHCA cause.

RESULTS

SDCT scans occurred within 1.9 ± 1.0 h of hospital arrival and identified 39% (41/104) of all OHCA causes and 95% (39/41) of causes potentially identifiable by SDCT. Critical findings were identified by SDCT in 98% (43/44) of patients that included potentially life-threatening resuscitation complications of liver or spleen laceration (n = 6); pneumothorax or thoracic organ laceration (n = 8); and mediastinal, pericardial, or vascular hemorrhage (n = 3). SDCT exclusively identified 13 (13%) OHCA causes that would otherwise not be identified without SDCT imaging. No inappropriate treatments resulted from SDCT findings. AKI was common (28%) but only one (1%) patient required new dialysis.

CONCLUSIONS

This observational cohort study suggests that early SDCT scanning is safe, can expedite the diagnosis of potential causes, and can meaningfully change clinical management after idiopathic OHCA.

GLASS Clinical Decision Rule Applied to Thoracolumbar Spinal Fractures in Patients Involved in Motor Vehicle Crashes

INTRODUCTION

There are established and validated clinical decision tools for cervical spine clearance. Almost all the rules include spinal tenderness on exam as an indication for imaging. Our goal was to apply GLASS, a previously derived clinical decision tool for cervical spine clearance, to thoracolumbar injuries. GLass intact Assures Safe Spine (GLASS) is a simple, objective method to evaluate those patients involved in motor vehicle collisions and determine which are at low risk for thoracolumbar injuries.

METHODS

We performed a retrospective cohort study using the National Accident Sampling System-Crashworthiness Data System (NASS-CDS) over an 11-year period (1998-2008). Sampled occupant cases selected in this study included patients age 16-60 who were belt-restrained, front- seat occupants involved in a crash with no airbag deployment, and no glass damage prior to the crash.

RESULTS

We evaluated 14,191 occupants involved in motor vehicle collisions in this analysis. GLASS had a sensitivity of 94.4% (95% CI [86.3-98.4%]), specificity of 54.1% (95% CI [53.2-54.9%]), and negative predictive value of 99.9% (95% CI [99.8-99.9%]) for thoracic injuries, and a sensitivity of 90.3% (95% CI [82.8-95.2%]), specificity of 54.2% (95% CI [53.3-54.9%]), and negative predictive value of 99.9% (95% CI [99.7-99.9%]) for lumbar injuries.

CONCLUSION

The GLASS rule represents the possibility of a novel, more-objective thoracolumbar spine clearance tool. Prospective evaluation would be required to further evaluate the validity of this clinical decision rule.

Clinical update. Computed Tomography — an Emerging Tool for Triple Rule-Out in the Emergency Department. A Review

New imaging tools have been developed in recent years to rapidly and accurately diagnose life-threatening diseases associated with high mortality rates, such as acute coronary syndromes, acute aortic dissection, or pulmonary embolism. The concept of using computed tomographic (CT) assessment in emergency settings is based on the possibility of excluding multiple acute pathologies within one scan. It can be used for patients complaining of acute chest pain of unclear etiology with the possible association of acute coronary dissection or pulmonary embolism, but only a low to moderate risk of developing an acute coronary syndrome. One of the benefits of this protocol is the possibility of decreasing the number of patients who are hospitalized for further investigations. The technique also allows the rapid triage of patients and the safe discharge of those who show negative results. The aim of this review is to summarize the current medical literature regarding the potential use of CT for the triple rule-out (TRO) of coronary etiologies.

Evolving Practice Patterns in Imaging Pregnant Patients With Acute Abdominal and Pelvic Conditions

OBJECTIVE

The purpose of our study was to determine the current practice patterns of U.S. radiologists in imaging pregnant or potentially pregnant patients with acute abdominal and pelvic conditions.

MATERIALS AND METHODS

After obtaining an Institutional Review Board waiver, all members of the Association of University Radiologists, the Association of Program Directors in Radiology, and the Society of Radiologists in Ultrasound were invited via e-mail to take a 23-question online survey on radiology practices and clinical scenarios about acute abdominal and pelvic imaging of pregnant patients.

RESULTS

Comparisons were made with previously published surveys. A total of 225 responses were received. Areas of high consensus included pregnancy assessment (97%) and obtaining informed consent (87%) before imaging, having a written policy on imaging pregnant patients (79%), modification of computed tomography (CT) protocols (74%), avoiding gadolinium contrast in magnetic resonance imaging (MRI) (74%), using ultrasound for initial imaging in some scenarios, and using CT in trauma cases after inconclusive ultrasound. Areas of emerging consensus compared to 2007 included the use of serum or urine testing to confirm pregnancy status (59.4%; previously 14%) and the use of MRI in suspected appendicitis after an inconclusive ultrasound (73% in first trimester and 67% in third trimester; previously 46% and 29%, respectively). Areas without clear consensus included policy development, additional modifications to MRI protocols, choice of imaging modality, radiation dose, and the use of contrast agents in some scenarios.

CONCLUSION

In conclusion, high or increasing consensus exists in some areas of imaging pregnant patients with acute abdominal and pelvic conditions, but has yet to emerge in other areas.

Calcium Scoring and Cardiac Computed Tomography

Although recent advances in noninvasive imaging technologies have potentially improved diagnostic efficiency and clinical outcomes of patients with acute chest pain, controversy remains regarding much of the accumulated evidence. This article reviews the role of coronary computed tomography (CT) angiography in the assessment of coronary risk, and its usefulness in the emergency department in facilitating appropriate disposition decisions. Also discussed is coronary artery calcification incidentally found on CT scans when done for indications such as evaluation of pulmonary embolism or lung cancer. The evidence base and clinical applications for both techniques are described, together with cost-effectiveness and radiation exposure considerations.

Detecting Facet Joint and Lateral Mass Injuries of the Subaxial Cervical Spine in Major Trauma Patients

STUDY DESIGN

Radiologic imaging measurement study.

PURPOSE

To assess the accuracy of detecting lateral mass and facet joint injuries of the subaxial cervical spine on plain radiographs using computed tomography (CT) scan images as a reference standard; and the integrity of morphological landmarks of the lateral mass and facet joints of the subaxial cervical spine.

OVERVIEW OF LITERATURE

Injuries of lateral mass and facet joints potentially lead to an unstable subaxial cervical spine and concomitant neurological sequelae. However, no study has evaluated the accuracy of detecting specific facet joint injuries.

METHODS

Eight spinal surgeons scored four sets of the same, randomly re-ordered, 30 cases with and without facet joint injuries of the subaxial cervical spine. Two surveys included conventional plain radiographs series (test) and another two surveys included CT scan images (reference). Facet joint injury characteristics were assessed for accuracy and reliability. Raw agreement, Fleiss kappa, Cohen's kappa and intraclass correlation coefficient statistics were used for reliability analysis. Majority rules were used for accuracy analysis.

RESULTS

Of the 21 facet joint injuries discerned on CT scan images, 10 were detected in both plain radiograph surveys (sensitivity, 0.48; 95% confidence interval [CI], 0.26-0.70). There were no false positive facet joint injuries in either of the first two X-ray surveys (specificity, 1.0; 95% CI, 0.63-1.0). Five of the 11 cases with missed injuries had an injury below the lowest visible articulating level on radiographs. CT scan images resulted in superior inter- and intra-rater agreement values for assessing morphologic injury characteristics of facet joint injuries.

CONCLUSIONS

Plain radiographs are not accurate, nor reliable for the assessment of facet joint injuries of the subaxial cervical spine. CT scans offer reliable diagnostic information required for the detection and treatment planning of facet joint injuries.

Coronary computed tomographic angiography in the emergency room: state of the art

Chest pain is a common complaint in the emergency department often necessitating testing to exclude underlying obstructive coronary artery disease. While the traditional evaluation of patients with suspected acute coronary syndrome often consists of serial electrocardiograms and cardiac biomarkers, followed by selective use of stress testing for further risk stratification, this approach is costly and inefficient. Recently, coronary computed tomographic angiography (CTA) has offered an alternative approach with a high sensitivity and negative predictive value to exclude obstructive coronary artery disease that can rapidly identify patients with low rates of downstream major adverse cardiac events. In this review, the authors provide an overview of available data on the use of CTA for evaluating acute chest pain, while emphasizing its advantages and disadvantages compared to existing strategies. In addition, we provide a suggested algorithm to identify how CTA can be incorporated into the evaluation of acute chest pain and discuss tips for successful implementation of CTA in the emergency department.

The role of computed tomography in musculoskeletal trauma

Computed tomography is the undisputed gold standard in the imaging of acute trauma, despite the introduction of focused assessment with sonography for trauma and magnetic resonance imaging. However, the role of computed tomography is far wider than just polytrauma imaging: its high spatial resolution, short scan times and very high sensitivity and specificities make computed tomography useful in the diagnosis of subtle injuries, as well as providing a general overview of other compartmental injuries. Three-dimensional reconstructions illustrates complex injury patterns clearly, aiding surgical planning and permitting accurate orthopaedic hardware follow-up. This article outlines some of the basic properties of computed tomography using examples from musculoskeletal trauma, to illustrate to clinicians what computed tomography can and cannot do for their practice.

[Triple rule-out computed tomography in emergency departments]

In the emergency department patients with chest pain play an important role because the underlying and concealed diseases can be life-threatening. The complaints are often nonspecific and patients also have different risk profiles. In patients in the emergency department with nonspecific chest pain a"1-stop strategy" for elucidation of the three main organs lung, hear and aorta with the 4 main differential diagnoses (aortic dissection, ruptured aortic aneurysm, pulmonary embolism and coronary heart disease) is desirable. Technical advances in computed tomography (CT) in recent years make this approach technically possible. In modern emergency departments CT equipment is becoming more and more common in order to rapidly examine trauma patients. A meaningful patient selection and preparation are, however, necessary to avoid unnecessary exposure of patients to contrast media and radiation. In this way it is possible to reduce the rate of overlooked diseases or false diagnoses.

Comparison of radiation dose and image quality of triple-rule-out computed tomography angiography between conventional helical scanning and a strategy incorporating sequential scanning

Triple-rule-out computed tomographic angiography (TRO CTA), performed to evaluate the coronary arteries, pulmonary arteries, and thoracic aorta, has been associated with high radiation exposure. The use of sequential scanning for coronary computed tomographic angiography reduces the radiation dose. The application of sequential scanning to TRO CTA is much less well defined. We analyzed the radiation dose and image quality from TRO CTA performed at a single outpatient center, comparing the scans from a period during which helical scanning with electrocardiographically controlled tube current modulation was used for all patients (n = 35) and after adoption of a strategy incorporating sequential scanning whenever appropriate (n = 35). Sequential scanning was able to be used for 86% of the cases. The sequential-if-appropriate strategy, compared to the helical-only strategy, was associated with a 61.6% dose decrease (mean dose-length product of 439 mGy × cm vs 1,144 mGy × cm and mean effective dose of 7.5 mSv vs 19.4 mSv, respectively, p <0.0001). Similarly, a 71.5% dose reduction occurred among the 30 patients scanned with the sequential protocol compared to the 40 patients scanned with the helical protocol using either strategy (326 mGy × cm vs 1,141 mGy × cm and 5.5 mSv vs 19.4 mSv, respectively, p <0.0001). Although the image quality did not differ between the strategies, a nonstatistically significant trend was seen toward better quality in the sequential protocol than in the helical protocol. In conclusion, approaching TRO CTA with a diagnostic strategy of sequential scanning, as appropriate, can offer a marked reduction in the radiation dose while maintaining the image quality.

What should an ideal spinal injury classification system consist of? A methodological review and conceptual proposal for future classifications

Since Böhler published the first categorization of spinal injuries based on plain radiographic examinations in 1929, numerous classifications have been proposed. Despite all these efforts, however, only a few have been tested for reliability and validity. This methodological, conceptual review summarizes that a spinal injury classification system should be clinically relevant, reliable and accurate. The clinical relevance of a classification is directly related to its content validity. The ideal content of a spinal injury classification should only include injury characteristics of the vertebral column, is primarily based on the increasingly routinely performed CT imaging, and is clearly distinctive from severity scales and treatment algorithms. Clearly defined observation and conversion criteria are crucial determinants of classification systems' reliability and accuracy. Ideally, two principle spinal injury characteristics should be easy to discern on diagnostic images: the specific location and morphology of the injured spinal structure. Given the current evidence and diagnostic imaging technology, descriptions of the mechanisms of injury and ligamentous injury should not be included in a spinal injury classification. The presence of concomitant neurologic deficits can be integrated in a spinal injury severity scale, which in turn can be considered in a spinal injury treatment algorithm. Ideally, a validation pathway of a spinal injury classification system should be completed prior to its clinical and scientific implementation. This review provides a methodological concept which might be considered prior to the synthesis of new or modified spinal injury classifications.

Triple-rule-out CT angiography for evaluation of acute chest pain and possible acute coronary syndrome

Triple-rule-out (TRO) computed tomographic (CT) angiography can provide a cost-effective evaluation of the coronary arteries, aorta, pulmonary arteries, and adjacent intrathoracic structures for the patient with acute chest pain. TRO CT is most appropriate for the patient who is judged to be at low to intermediate risk for acute coronary syndrome (ACS) and whose symptoms may also be attributed to acute pathologic conditions of the aorta or pulmonary arteries. Although a regular cardiac rhythm remains an important factor in coronary CT image quality, newer CT scanners with 64 or more detector rows afford rapid electrocardiographically (ECG) gated imaging to provide high-quality TRO CT studies in patients with a heart rate of up to 80 beats per minute. Injection of iodinated contrast material (< or = 100 mL) is tailored to provide simultaneous high levels of arterial enhancement in the coronary arteries and aorta (> 300 HU) and in the pulmonary arteries (> 200 HU). To limit radiation exposure, the TRO CT examination does not include the entire chest but is constrained to incorporate the aortic arch down through the heart. Scanning parameters, including prospective ECG tube current modulation and prospective ECG gating with the "step-and-shoot" technique, are tailored to reduce radiation exposure (optimally, 5-9 mSv). When performed with appropriate attention to timing and technique, TRO CT provides coronary image quality equal to that of dedicated coronary CT angiography and pulmonary arterial images that are free of motion artifact related to cardiac pulsation. In an appropriately selected emergency department patient population, TRO CT can safely eliminate the need for further diagnostic testing in over 75% of patients.

Comparison of image quality and arterial enhancement with a dedicated coronary CTA protocol versus a triple rule-out coronary CTA protocol

RATIONALE AND OBJECTIVES

To compare the image quality of dedicated coronary computed tomography angiography (cCTA) to that of triple rule-out (TRO) CTA designed to evaluate the coronary arteries, thoracic aorta, and pulmonary arteries.

MATERIALS AND METHODS

Consecutive cCTA examinations performed by a single radiologist over 1 year were reviewed. Biphasic injection protocols were employed: 70 mL of optiray-350 followed by 40 mL of saline injected at 5.5 mL/second for dedicated cCTA; 70 mL of optiray-350 followed by 25 mL of the contrast diluted with 25 mL of saline injected at 5.0 mL/second for TRO-CTA. Two independent cardiovascular radiologists reviewed the coronary vessels in each case and rated diagnostic image quality on a 5 point scale (1, suboptimal; 3, adequate; 5, excellent). Vascular enhancement was measured in the coronary arteries, aorta, and pulmonary arteries.

RESULTS

There was excellent interobserver agreement between the cardiovascular radiologists (kappa = 0.91). Coronary image quality score were similar among 260 dedicated cCTA studies and 168 TRO-CTA studies (mean: 3.8-3.9. P > .18). At least one coronary segment demonstrated suboptimal image quality in 8% of examinations, including 18 dedicated cCTA studies and 16 TRO studies (P = .94). Enhancement was greater in the distal thoracic aorta of TRO patients (336 vs. 311 Hounsfield units; P = .01); no other significant differences in enhancement were identified in the aorta and coronary arteries of dedicated cCTA and TRO studies. Vascular enhancement was adequate for diagnostic evaluation of the pulmonary arteries in all TRO studies.

CONCLUSIONS

A TRO-CTA protocol using 95 mL of contrast can provide comparable coronary image quality and coronary vascular enhancement as compared to dedicated cCTA with 70 mL of contrast.