Radiologic blind spots in hip and pelvic radiographs.

PURPOSE: The purpose of our study was to identify the locations at which hip and pelvic fractures are commonly missed on radiographs. METHODS: A retrospective study was performed at four non-Level 1 trauma center emergency departments. IRB approval was obtained. All emergency department hip or pelvic radiographs with subsequent CT performed within 48 h were identified from 2017 to 2022. Reports for each radiograph and CT were scored for the presence or the absence of fracture in the following locations: ilium, sacrum, superior pubic ramus, inferior pubic ramus, pubis, acetabulum, subcapital femoral, femoral neck, greater trochanter, lesser trochanter, intertrochanteric, and subtrochanteric. The CT report was used as the gold standard. The false-negative radiography cases were reviewed on a PACS workstation to determine whether the case had an "unexpected miss" of a fracture, a subtle fracture, radiographically occult fracture, or exam was limited by artifact. The percentage of missed fractures at each location was calculated. RESULTS: Nine hundred seventy-five radiography cases with subsequent CT were identified. One hundred forty-six cases did not meet entry criteria; therefore, 829 cases were analyzed further. Seventy-four percent of patients were female with age of 74 ± 16 (mean ± standard deviation) years (range 1-103). Three hundred fifty-two cases had at least one fracture, and many cases had multiple fractures. There were 68 false-negative cases. The most commonly missed fractures by percentage were pubis, ilium, and greater trochanter. The most common unexpectedly missed fractures were greater trochanter and femoral subcapital. CONCLUSION: A careful systematic evaluation of hip and pelvic radiographs, with particular attention to the pubis, ilium, greater trochanter, and subcapital region, may improve radiographic fracture detection and decrease delays in diagnosis.

Update on establishing and managing an overnight emergency radiology division.

Emergency department (ED) radiology divisions that serve to provide overnight attending coverage have become an increasingly common feature of radiology departments. The purpose of this article is to review the common ED radiology coverage models, describe desirable traits of emergency radiologists, and discuss workflow in the ED radiology setting. ED radiologists may be trained as ED radiologists or may develop the necessary skills and adopt the subspecialty. Choosing radiologists with the correct traits such as being a "night owl" and remaining calm under pressure and implementing an acceptable work schedule such as shift length of 9-10 h and a "one week on, two weeks off" schedule contribute to sustainability of the position. Strategies to address the unique stressors and workflow challenges of overnight emergency radiology coverage are also presented. Workflow facilitators including trainees, PAs, radiology assistants, and clerks all have roles to play in managing high case volumes and in making sure that the service is well staffed. Usage of artificial intelligence software is the latest technique to streamline workflow by identifying cases which should be prioritized on a busy worklist. Implementing such strategies will maintain quality of care for patients regardless of time of day as well as sustainability and quality of life for overnight emergency radiologists.

Lower-extremity Arterial Thrombosis Associated with COVID-19 Is Characterized by Greater Thrombus Burden and Increased Rate of Amputation and Death.

Background During the peak of the coronavirus disease 2019 (COVID-19) pandemic, the authors noted an increase in positive lower-extremity CT angiography examinations in patients who presented with leg ischemia. The goal of this study was to determine whether lower-extremity arterial thrombosis was associated with COVID-19 and whether it was characterized by greater severity in these patients. Materials and Methods In this retrospective propensity score-matched study approved by the institutional review board, 16 patients who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and who underwent CT angiography of the lower extremities and 32 patients who tested negative for SARS-CoV-2 observed from January to April 2018, January to April 2019, and January to April 2020 were compared using three scoring systems: two systems including all vessels, with weighting in one system given to more proximal vessels and with weighting in the other system given to more distal vessels, and a third system in which only the common iliac through popliteal arteries were considered. Correlation with presenting symptoms and outcomes was computed. Fisher exact tests were used to compare patients who tested positive for COVID-19 with patients who tested negative for COVID-19 regarding the presence of clots and presenting symptoms. A Mantel-Haenszel test was used to associate outcome of death and/or amputation with COVID-19 adjusted according to history of peripheral vascular disease (PVD). Results Sixteen patients with confirmed COVID-19 (70 years ± 14 [standard deviation]; seven women) who underwent CT angiography and 32 propensity score-matched control patients (71 years ± 15; 16 women) were included. All patients with COVID-19 (100%, 95% confidence interval [CI]: 79%, 100%) had at least one thrombus, and only 69% of control patients (95% CI: 50%, 84%) had thrombi (P = .02). Ninety-four percent of patients with COVID-19 (95% CI: 70%, 99.8%) had proximal thrombi compared with 47% of control patients (95% CI: 29%, 65%) (P < .001). The mean thrombus score using any of the three scoring systems yielded greater scores in patients with COVID-19 (P < .001). Adjusted for history of PVD, death or limb amputation was more common in patients with COVID-19 (odds ratio = 25; 95% CI: 4.3, 147; P < .001). Patients with COVID-19 who presented with symptoms of leg ischemia only were more likely to avoid amputation or death than patients who also presented with pulmonary or systemic symptoms (P = .001). Conclusion Coronavirus disease 2019 is associated with lower-extremity arterial thrombosis characterized by a greater clot burden and a more dire prognosis. © RSNA, 2020.

Imaging of Lumen-Apposing Metal Stents in Abdominopelvic Applications.

OBJECTIVE. Lumen-apposing metal stents (LAMS) are increasingly being used for abdominopelvic drainage applications. The purpose of this article is to describe the normal imaging appearance of these stents and the radiologic findings in stent-related complications. CONCLUSION. LAMS facilitate effective drainage, but the complications include bleeding, pseudoaneurysm formation, stent occlusion, and stent migration.

CT of the Neck: Image Analysis and Reporting in the Emergency Setting.

Interpreting findings seen at CT of the neck is challenging owing to the complex and nuanced anatomy of the neck, which contains multiple organ systems in a relatively small area. In the emergency department setting, CT is performed to investigate acute infectious or inflammatory symptoms and chronic processes. With few exceptions, neck CT should be performed with intravenous contrast material, which accentuates abnormally enhancing phlegmonous and neoplastic tissues and can be used to delineate any abscesses or necrotic areas. As part of the evaluation, the vascular structures and aerodigestive tract must be scrutinized, particularly for patency. Furthermore, although the patient may present because of symptoms that suggest non-life-threatening conditions involving structures such as the teeth or salivary glands, there may be serious implications for other areas, such as the orbits, brain, and spinal cord, that also may be revealed at the examination. With a focus on the emergency setting, the authors propose using an approach to interpreting neck CT findings whereby 12 areas are systematically evaluated and reported on: the cutaneous and subcutaneous soft tissues, aerodigestive tract and adjacent soft tissues, teeth and periodontal tissues, thyroid gland, salivary glands, lymph nodes, vascular structures, bony airspaces, cervical spine, orbits and imaged brain, lung apices, and superior mediastinum. The use of a systematic approach to interpreting neck CT findings is essential for identifying all salient findings, recognizing and synthesizing the implications of these findings to formulate the correct diagnosis, and reporting the findings and impressions in a complete, clear, and logical manner.Online supplemental material is available for this article.©RSNA, 2019.

Implantable Electronic Stimulation Devices from Head to Sacrum: Imaging Features and Functions.

Electronic stimulation devices are implanted in various locations in the body to decrease pain, modulate nerve function, or stimulate various end organs. The authors describe these devices using a craniocaudal approach, first describing deep brain stimulation (DBS) devices and ending with sacral nerve stimulation (SNS) devices. The radiology-relevant background information for each device and its imaging appearance are also described. These devices have a common design theme and include the following components: (a) a pulse generator that houses the battery and control electronics, (b) an insulated lead or wire that conveys signals to the last component, which is (c) an electrode that contacts the end organ and senses and/or acts on the end organ. DBS electrodes are inserted into various deep gray nuclei, most commonly to treat the symptoms of movement disorders. Occipital, trigeminal, and spinal nerve stimulation devices are used as second-line therapy to control craniofacial or back pain. For cardiac devices, the authors describe two newer devices, the subcutaneous implantable cardioverter defibrillator and the leadless pacemaker, both of which avoid complications related to having leads threaded through the venous system. Diaphragmatic stimulation devices stimulate the phrenic nerve to restore diaphragmatic movement. Gastric electrical stimulation devices act on various parts of the stomach for the treatment of gastroparesis or obesity. Finally, SNS devices are used to modulate urinary and defecatory functions. Common complications diagnosed at imaging include infection, hematoma, lead migration, and lead breakage. Understanding the components, normal function, and normal imaging appearance of each device allows the radiologist to identify complications. ©RSNA, 2019.

Diagnostic yield of head CT in pediatric emergency department patients with acute psychosis or hallucinations.

BACKGROUND: Children presenting to the emergency department with acute psychosis or hallucinations sometimes undergo a head CT to evaluate for a causative lesion. The diagnostic yield of head CT in this scenario has not been reported. OBJECTIVE: To determine the yield for head CT in children with acute psychosis or hallucinations. MATERIALS AND METHODS: We retrospectively searched the radiology report database over a 7.5-year period for head CT reports for pediatric emergency department patients using the following keywords: hallucination, psychosis, psychotic or "hearing voices." All reports were categorized as normal or abnormal, and we reviewed and categorized the abnormal cases. We calculated the 95% confidence interval for abnormal CTs using the method of Clopper and Pearson. RESULTS: We identified 397 pediatric emergency department head CTs. We excluded one non-diagnostic exam. We excluded 34 additional cases (which were all normal) because of clinical indications that might have independently triggered a head CT. Of the remaining 362 cases, 12 reports described abnormalities or variants and we reviewed them individually. Based on consensus review, four were normal, four had congenital malformations, three had encephalomalacia versus demyelination and one demonstrated cortical atrophy. There were no cases with actionable findings such as mass, hemorrhage, infection or hydrocephalus. The 95% confidence interval for a CT demonstrating causative findings was calculated at 0-0.82%. CONCLUSION: In the absence of concerning factors such as focal neurological deficits, evidence of central nervous system infection, trauma or headache, routine screening head CT might not be warranted in children presenting with acute psychosis or hallucinations.

New CT-based diagnoses of torso cancer is low in the emergency department setting.

PURPOSE: The incidence of new CT-based torso cancer diagnoses and the most commonly diagnosed cancer types in the emergency department (ED) setting are unknown. The purpose of our study was to determine the incidence and types of new CT-based torso cancer diagnoses in the ED. METHODS: A total of 19,496 CT reports including all or parts of the torso from 2017 were searched for the keywords: "mass", "tumor", "neoplasm", "malignancy", or "cancer". Each report and corresponding medical record was evaluated for presence of a new cancer. Cases were scored as no cancer, subcentimeter lung nodule, known cancer, new cancer, or suspicious, but unconfirmed for new cancer. Each mass was characterized as symptom-related or incidental. RESULTS: At least one keyword was found in 2086 reports. Of these 706, 126 and 905 were known cancer cases, subcentimeter lung nodules, and non-cancerous cases, respectively. There were 251 confirmed new cancers and 98 suspicious cases which lacked adequate diagnostic workup. Depending on whether only definite or definite and suspicious cases were included together, the number of new cancer cases per 100 torso CT exams was 1.3 or 1.8, respectively. Gastrointestinal, lung, pancreaticobiliary, urinary, and gynecologic cancers were most common. Only 58 of the confirmed cases (23%) were deemed as incidental findings. CONCLUSION: CT-diagnosis of new torso cancers was uncommon in our setting. Still, while extensive knowledge of cancer staging may not be necessary for ED radiologists, knowledge of the most common types of cancer including gastrointestinal, lung, pancreaticobiliary, urinary, and gynecologic cancers may improve sensitivity for these diagnoses and may expedite appropriate referrals for the newly diagnosed patients.

Causes of pneumocephalus and when to be concerned about it.

Intracranial gas is commonly detected on neuroimaging. The recognition of this finding can at first blush be unsettling. Being able to localize this gas to a specific compartment: intraarterial, intravenous, intraparenchymal, subdural, epidural, subarachnoid and intraventricular, is the first step in determining the importance of the gas. Determination of the route of entry: through the skull, extension from a paranasal sinus or the mastoid air cells, via the spine, or trans-vascular, is the other important factor in determining potential consequences. Understanding these parameters allows for a confident determination of etiology. More importantly, it generally provides guidance as to what must be done: either to disregard (e.g., subarachnoid gas following lumbar puncture and intravenous gas following IV placement), obtain follow-up (e.g., postoperative gas), or administer emergent treatment (e.g., intraarterial gas and epidural abscess). In this review, we use gas location and route of entry to classify the various causes of pneumocephalus and provide examples of each of these etiologies.

MRI usage in a pediatric emergency department: an analysis of usage and usage trends over 5 years.

BACKGROUND: Magnetic resonance imaging (MRI) usage has anecdotally increased due to the principles of ALARA and the desire to Image Gently. Aside from a single abstract in the emergency medicine literature, pediatric emergency department MRI usage has not been described. OBJECIVE: Our objective was to determine whether MRI use is indeed increasing at a high-volume urban pediatric emergency department with 24/7 MRI availability. Also, we sought to determine which exams, time periods and demographics influenced the trend. MATERIALS AND METHODS: Institutional Review Board exemption was obtained. Emergency department patient visit and exam data were obtained from the hospital database for the 2011-2015 time period. MRI usage data were normalized using emergency department patient visit data to determine usage rates. The z-test was used to compare MRI use by gender. The chi-square test was used to test for trends in MRI usage during the study period and in patient age. MRI usage for each hour and each weekday were tabulated to determine peak and trough usage times. RESULTS: MRI usage rate per emergency department patient visit was 0.36%. Headache, pain and rule-out appendicitis were the most common indications for neuroradiology, musculoskeletal and trunk exams, respectively. Usage in female patients was significantly greater than in males (0.42% vs. 0.29%, respectively, P<0.001). Usage significantly increased during the 5-year period (P<0.001). Use significantly increased from age 3 to 17 (0.011% to 1.1%, respectively, P<0.001). Sixty percent of exams were performed after-hours, the highest volume during the 10 p.m. hour and lowest between 4 a.m. and 9 a.m. MRI use was highest on Thursdays and lowest on Sundays (MRI on 0.45% and 0.22% of patients, respectively). CONCLUSION: MRI use in children increased during the study period, most notably in females, on weekdays and after-hours.

A radiologist's guide to the clinical scales used in the 2015 Endovascular Stroke Trials and the Revised American Heart Association/American Stroke Association Guidelines for Endovascular Stroke Treatment.

In 2015, five trials demonstrated the efficacy of endovascular treatment for acute stroke, culminating in the revised American Heart Association/American Stroke Association (AHA/ASA) recommendations for stroke management. The different clinical scales used in these trials may be unfamiliar to emergency and on-call radiologists. The modified Rankin Scale was used to describe patient disability for prestroke assessment in three of the trials and for the 90-day follow up in all five trials. The Barthel index was used in one trial to score prestroke ability to perform activities of daily living. The NIH Stroke Scale was used as part of eligibility criteria in four of the stroke trials to assess pre-existing neurological deficits. Also, the modified Rankin Scale and the NIH Stroke Scale are used in the revised AHA/ASA recommendations. By understanding these scales, emergency and on-call radiologists will better appreciate the stroke patient's condition and will be able to more actively collaborate in the care of acute stroke patients.

Acetabular fractures: what radiologists should know and how 3D CT can aid classification.

Correct recognition, description, and classification of acetabular fractures is essential for efficient patient triage and treatment. Acetabular fractures may result from high-energy trauma or low-energy trauma in the elderly. The most widely used acetabular fracture classification system among radiologists and orthopedic surgeons is the system of Judet and Letournel, which includes five elementary (or elemental) and five associated fractures. The elementary fractures are anterior wall, posterior wall, anterior column, posterior column, and transverse. The associated fractures are all combinations or partial combinations of the elementary fractures and include transverse with posterior wall, T-shaped, associated both column, anterior column or wall with posterior hemitransverse, and posterior column with posterior wall. The most unique fracture is the associated both column fracture, which completely dissociates the acetabular articular surface from the sciatic buttress. Accurate categorization of acetabular fractures is challenging because of the complex three-dimensional (3D) anatomy of the pelvis, the rarity of certain acetabular fracture variants, and confusing nomenclature. Comparing a 3D image of the fractured acetabulum with a standard diagram containing the 10 Judet and Letournel categories of acetabular fracture and using a flowchart algorithm are effective ways of arriving at the correct fracture classification. Online supplemental material is available for this article.

The impact of on-site attending radiologist overnight coverage on radiology resident learning: a preliminary assessment.

The objective of this study is to assess the impact of on-site attending radiologist overnight coverage on resident education during transition to 24/7 attending coverage. The study was exempted from IRB review. An anonymous survey was sent to 9 second year radiology residents who completed their first night call rotation (NC) with an attending radiologist (group 1) and 18 residents who completed their first NC prior to overnight attending coverage (group 2). This addressed anxiety level prior to NC, work pace, autonomy and confidence, and attending feedback, with responses graded on a five-point scale. Statistical analysis was performed using Spearman's rho correlation coefficient. Diagnostic Radiology In-Training (DXIT(TM)) exam scores were collected prior to and following completion of the NC rotation, and results were compared. Case volume before and after the transition was recorded. p value <0.05 indicated statistical significance. Eight out of nine residents in group 1 and 16 out of/18 residents in group 2 completed the survey. Group 1 was more likely to report working at a comfortable pace (p = 0.008) and receiving attending feedback (p = 0.004) than group 2. A non-significant trend towards reduced anxiety prior to NC was present in group 1 (p = 0.077). No difference in independence (p = 0.918), autonomy (p = 0.635), or confidence during (p = 0.431) or after NC (p = 1.00) was identified. DXIT(TM) scores were not significantly different between the two groups (p = 0.396). While overall case volume dictated by residents increased, fewer plain radiographs were dictated. Overnight attending coverage provides a more comfortable pace of study interpretation and increased attending feedback without decreasing resident independence or DXIT(TM) scores. Plain radiograph interpretation may need to be further emphasized.

Significance of post-traumatic maxillary sinus fluid, or lack of fluid, in a level II trauma population.

Our goal was to test the predictive value of high-attenuation material within the maxillary sinus for adjacent facial bone fracture. After IRB approval, all blunt trauma facial CTs performed over a 5-month period at a level II trauma center were reviewed in consensus by three radiologists for the presence of facial fractures or high attenuation maxillary sinus opacity (≥30HU, ≥40HU, or ≥50HU). Three classes of fractures were analyzed: any fracture, any fracture contiguous with the maxillary sinus, and only fractures not contiguous with the maxillary sinus. Statistics were calculated using two-by-two tables. A total of 844 cases were reviewed with 273 patients having any fracture. There were 402 hemi-faces with any fracture and 62 hemi-faces with fracture contiguous with the maxillary sinus. Sensitivity, specificity, positive predictive value, and negative predictive value for any fracture (using the ≥40HU threshold) were 13, 99, 85, and 78 % respectively; for fracture contiguous with the sinus, these were 71, 99, 72, and 99 % respectively; and for only non-contiguous fractures, these were 2.3, 96, 13, and 80 %, respectively. We conclude that in this level II trauma population, lack of high attenuation maxillary sinus material nearly ruled out fractures in contiguity with the sinus. High-attenuation sinus material is only moderately predictive of a fracture contiguous with the maxillary sinus. Therefore, if after careful review a fracture is not identified, the radiologist should not be overly concerned that a fracture is being missed. High-attenuation sinus material is a poor marker for fractures not contiguous with the maxillary sinus.

Beyond ultrasound: CT and MRI of ectopic pregnancy.

OBJECTIVE: Although ultrasound is the primary modality used in the diagnosis of ectopic pregnancy, various forms of this condition and their complications may occasionally be further evaluated with MRI or may be incidentally detected on CT or MRI when an alternative diagnosis is suspected. CONCLUSION: Various types of ectopic pregnancy have characteristic imaging features. Radiologists should be familiar with these features and should always consider the possibility of ectopic pregnancy in the setting of hemoperitoneum or a pelvic mass in a woman of child-bearing age. Familiarity with the typical CT and MRI appearances of various forms of ectopic pregnancy facilitates prompt and accurate diagnosis and treatment.

Gastric pneumatosis: Laboratory and imaging findings associated with mortality in adults.

AIM: To describe laboratory and imaging findings associated with mortality in patients with gastric pneumatosis. MATERIALS AND METHODS: Institution review board approval was obtained for this retrospective study. Using radiology report databases, all patients with "gastric pneumatosis" or "emphysematous gastritis" in their CT reports were identified from two institutions during 12 or 9 year periods. Clinical parameters and laboratory values [lactic acid, white blood cell (WBC) count, and serum creatinine] were obtained from medical records and images were reviewed in consensus by two readers. Bivariate associations between continuous variables were tested by Mann-Whitney tests. Fisher's exact test was used to evaluate bivariate associations between categorical variables. RESULTS: Of the 24 patients identified, there were five (21%) deaths. Median serum lactic acid and creatinine levels were significantly higher in patients who died compared to surviving patients [median (interquartile range, IQR): 1.95 (1.45-4.15) versus 1.5 (1.3-2.6), p = 0.001; 1.2 (1-2.8) versus 1 (0.8-1.4), p = 0.005, respectively). There was no significant difference in WBC levels between the groups. Coexistent small bowel pneumatosis and colonic pneumatosis were significantly more common in patients who died compared to surviving patients (80% versus 0%, p < 0.001; 40% versus 0%, p = 0.04, respectively). There was no significant difference for portal or mesenteric venous gas, free intraperitoneal gas, or dilated bowel. CONCLUSIONS: When the imaging finding of gastric pneumatosis was associated with elevated serum lactic acid, elevated serum creatinine, or concomitant small bowel or colonic pneumatosis, an association with mortality was observed. These findings suggest that more aggressive treatment may be warranted in patients with these laboratory or imaging abnormalities.

Renal stones on portal venous phase contrast-enhanced CT: does intravenous contrast interfere with detection?

PURPOSE: To determine the sensitivity of portal venous phase contrast-enhanced CT for the detection of renal stones. METHODS: This retrospective study included 97 CT examinations of the abdomen without and with intravenous contrast, including 85 (87.6%) examinations with at least one renal stone on the "gold standard" noncontrast images, as scored by a single radiologist. Three other radiologists each independently reviewed only the contrast-enhanced images from all 97 examinations and recorded all renal stones. Reviewer sensitivity for stones was categorized by stone diameter. Reviewer sensitivity and specificity for stone disease were also calculated on a per-kidney basis. RESULTS: The 97 cases included a total of 238 stones ≥1 mm, with a mean (±SD) of 1.2 ± 1.9 stones per kidney and a stone diameter of 3.5 ± 3.0 mm. Pooling data for the three reviewers, sensitivity for all stones was 81%; sensitivity for stones ≥2, ≥3, ≥4, and ≥5 mm was 88%, 95%, 99%, and 98%, respectively. Sensitivity for stone disease on a per-kidney basis was 94% when considering all stones; when considering only stones ≥2, ≥3, and ≥4 mm, sensitivity was 96%, 99%, and 100%, respectively. Specificity for stone disease on a per-kidney basis was 98% overall, 99% when considering only stones ≥2 mm, and 100% when considering only stones ≥3 mm. CONCLUSION: Contrast-enhanced CT is highly sensitive for the detection of renal stones ≥3 mm in diameter and less sensitive for smaller stones. In cases where the clinical diagnosis is uncertain and performance of a CT examination is being contemplated, intravenous contrast utilization would allow assessment for stone disease while also optimizing evaluation for other conditions.

High attenuation pericardial fluid on CT following cardiac catheterization.

High-density pericardial fluid may be seen on noncontrast CT performed following cardiac catheterization (CC), raising the possibility of hemopericardium. Our goal was to determine the clinical course and associations of incidentally discovered high-attenuation pericardial fluid on noncontrast CT performed soon after CC. Hospital database search over a 7.5-year period identified 211 patients who underwent CT of the chest and/or abdomen within 60 h before or after CC, 150 having CC first. Pericardial fluid volume and attenuation as well as relevant laboratory and clinical parameters were recorded. Bivariate associations with average pericardial fluid attenuation (HUavg) were assessed. Using the 61 patients with CT before CC as controls, 44 of the patients with CC first had attenuation values greater than the mean + 2SD of 22.6 Hounsfield unit (HU) and 19 had attenuation values greater than the maximum control patient value of 39.8 HU. All patients with incidental finding of high-density pericardial fluid followed a benign course. Bivariate correlations showed time gap between CC and CT (rho = -0.50, p < 0.001), estimated glomerular filtration rate (eGFR) (rho = -0.24, p = 0.004), and female gender (median (IQR) 17.4 (13.6, 29.6) vs. 15.8 (9.9, 23.7), p = 0.02) to be associated with HUavg. In multiple linear regression analysis, only time gap and female gender were independently significantly associated with average attenuation (both p < 0.001). The finding that patients with incidentally discovered high-density pericardial fluid followed an uneventful course suggests a benign etiology such as vicarious excretion, and in patients who are otherwise stable, observation rather than immediate intervention should be considered.