The role of an abbreviated ultrasound in the evaluation of necrotizing enterocolitis.

BACKGROUND: Bowel ultrasound is a useful diagnostic tool in the diagnosis and management of necrotizing enterocolitis (NEC) but can be time-consuming and requires technical expertise, particularly for assessing pneumatosis. Previous literature on sonographic evaluation of NEC has focused on a full bowel ultrasound protocol, but the utility of an abbreviated protocol primarily aimed at identifying high-risk sonographic findings without focused bowel assessment has not been well studied. OBJECTIVE: This study aims to describe the diagnostic accuracy of an abbreviated ultrasound protocol for identifying high-risk NEC findings. MATERIALS AND METHODS: This is a retrospective, institutional review board-approved study. We identified all abbreviated NEC ultrasounds performed between January 2014 and August 2022 at our institution. Exams were reviewed for the presence of high-risk findings including pneumoperitoneum, fluid collections, and complex free fluid. Clinical outcome was categorized as poor or good depending on if emergent surgical intervention or death related to NEC occurred. The frequency of follow-up NEC ultrasounds was reviewed to determine if new findings affected outcome. Sensitivity, specificity, and positive and negative predictive values were generated to assess the performance of the abbreviated ultrasounds to identify high-risk findings. RESULTS: A total of 84 abbreviated abdominal ultrasounds were performed on 73 children. Median age at the time of ultrasound was 41 days (interquartile range (IQR) 53 days) and median gestational age was 35 weeks and 3 days (IQR 80 days), and 44/73 (60%) were male. Thirteen ultrasounds had at least one high-risk finding with nine (69%) resulting in a poor outcome, including seven surgical interventions and four deaths. Two patients had surgical intervention and died as a result of necrotizing enterocolitis. Ultrasounds without high-risk findings were not associated with poor clinical outcomes. Sensitivity, specificity, positive predictive value, and negative predictive value of the abbreviated NEC ultrasound were 100% (95% CI 60-100%), 95% (95% CI 86-98%), 69% (95% CI 39-90%), and 100% (95% CI 94-100%), respectively. Twelve abbreviated ultrasounds were followed by a second NEC ultrasound within 5 days. Five follow-up ultrasounds demonstrated new high- or low-risk findings, but the new findings did not correlate with a change in outcome as predicted by the initial ultrasound. CONCLUSION: An abbreviated NEC ultrasound can be of clinical utility in predicting poor outcomes, particularly during non-business hours when resources are limited.

Ultrasound for necrotizing enterocolitis: how can we optimize imaging and what are the most critical findings?

Necrotizing enterocolitis (NEC) is a common condition in the neonatal intensive care unit that continues to present challenges in terms of diagnosis and management. Traditionally NEC has been diagnosed and managed by clinical and radiographic findings, but US has shown promise in characterizing and prognosticating NEC. In this manuscript we review the abdominal US technique for NEC, the clinical significance of individual sonographic findings of NEC, and how US can be integrated in the clinical decision process for diagnosing and managing NEC. We also discuss the potential value-added role of a limited abdominal US protocol that focuses on the sonographic findings most indicative of a poor prognosis to include pneumoperitoneum, complex free fluid and focal fluid collections.

The ductus arteriosus: a review of embryology to intervention.

This article reviews the physiology of the ductus arteriosus, the pathophysiology of the patent ductus arteriosus (PDA), and the role advanced imaging such as computed tomography (CT) and magnetic resonance imaging (MRI) can play in guiding diagnosis and percutaneous or surgical intervention. A PDA can have variable clinical and radiologic presentations and can be important to characterize in patients with vascular rings, aortic maldevelopment and congenital heart disease. An understanding of the PDA and the application of CT and MRI can allow the radiologist to provide key information to physicians who plan to close a PDA or maintain PDA patency in the setting of ductal-dependent congenital heart disease.

Ultrasound imaging of diaphragmatic motion.

The diaphragm is the key muscle of respiration, especially in infants. Diaphragmatic dysfunction and paralysis can have significant implications for medical management and treatment, and they can be challenging to diagnose by clinical parameters alone. Multiple imaging modalities are useful for assessing the diaphragm, but US - specifically M-mode US - offers several distinct advantages and few limitations compared to fluoroscopy, radiography, CT and MRI. The purpose of this manuscript is to discuss the pathophysiology of the diaphragm, review common indications for dynamic diaphragmatic US, describe optimal imaging technique, and discuss how to avoid imaging pitfalls.

Value of emergent pediatric cardiac computed tomographic angiography service: initial experience at a large children's hospital.

BACKGROUND: Demand for pediatric cardiac computed tomography (CT) angiography is increasing due to recent advances that reduce the need for sedation and radiation exposure while enhancing diagnostic accuracy. This has resulted in the increasing use of cardiac CT angiography emergently during weekends and after hours. The unexpected demand for these services can be challenging, as most hospitals are not staffed to provide 24/7 pediatric cardiovascular imaging. OBJECTIVE: To describe a large single-center experience of providing emergent cardiac CT angiography services in children. MATERIALS AND METHODS: We identified all patients who underwent after--hours weekday and weekend emergent cardiac CT angiography between January 2017 and August 2018. Cardiac CT angiography in the settings of congenital heart disease and coronary imaging were included. Data collected included day and time of cardiac CT angiography, patient age, referral unit, indication, surgical history, need for sedation, need for surgery, intervention and/or change in medical management based on the cardiac CT angiography. RESULTS: Forty-seven studies were identified, 26 (55%) of which were performed on a weekend or holiday and 21 (45%) after 5 p.m. on a weekday. Based on cardiac CT angiography findings, 20 (43%) patients underwent either surgery or an interventional procedure, and 9 (19%) had a change in medical management. The time between cardiac CT angiography and the related surgery/intervention ranged from 0 to 29 days with a median of 3.5 days. CONCLUSION: Emergent pediatric cardiac CT angiography is a valuable service. Larger multi-institutional studies with standardized referral and utilization patterns are needed to determine if outcomes are affected by this service, which in turn will influence hospital staffing patterns for emergent imaging.

A novel approach using volumetric dynamic airway computed tomography to determine positive end-expiratory pressure (PEEP) settings to maintain airway patency in ventilated infants with bronchopulmonary dysplasia.

BACKGROUND: Positive end-expiratory pressure (PEEP) is a key mechanical ventilator setting in infants with bronchopulmonary dysplasia (BPD). Excessive PEEP can result in insufficient carbon dioxide elimination and lung damage, while insufficient PEEP can result in impaired gas exchange secondary to airway and alveolar collapse. Determining PEEP settings based on clinical parameters alone is challenging and variable. OBJECTIVE: The purpose of this study was to describe our experience using dynamic airway CT to determine the lowest PEEP setting sufficient to maintain expiratory central airway patency of at least 50% of the inspiratory cross-sectional area in children with BPD requiring long-term ventilator support. MATERIALS AND METHODS: We retrospectively identified all infants with BPD who underwent volumetric CT with a dynamic airway protocol for PEEP optimization from December 2014 through April 2019. Sixteen infants with BPD underwent 17 CT exams. Each CT exam consisted of acquisitions spanning the trachea and mainstem bronchi. We measured cross-sectional area of the trachea and mainstem bronchi and qualitatively assessed the amount of atelectasis. We documented changes in management as a result of the CT exam. RESULTS: The average effective dose was 0.1-0.8 mSv/scan. Of 17 CT exams, PEEP was increased in 9, decreased in 3 and unchanged after 5 exams. CONCLUSION: Dynamic airway CT shows promise to assist the clinician in determining PEEP settings to maintain airway patency in infants with BPD requiring long-term ventilator support. Further evaluation of the impact of this maneuver on gas exchange, cardiac output and other physiological measures is needed.

MRI for Pediatric Appendicitis in an Adult-Focused General Hospital: A Clinical Effectiveness Study-Challenges and Lessons Learned.

OBJECTIVE: The objective of our study was to determine the feasibility and accuracy of MRI for pediatric appendicitis in an adult-predominant general hospital setting where non-pediatric-trained radiologists routinely interpret the studies. MATERIALS AND METHODS: MRI was performed in pediatric patients with equivocal ultrasound (US) findings and persistent clinical concern for appendicitis. Neither IV contrast material nor a sedative was administered. Our MRI protocol evolved early during the study period, quickly settling on three sequences (total scanning time, 11 minutes). The clinical reference standard for statistical analysis was appendicitis diagnosed on operative or pathology report; 95% Clopper-Pearson CIs were calculated. RESULTS: Between 2012 and 2016, 528 pediatric patients (mean age, 9.9 years; age range, 1-17 years) underwent MRI after US evaluation yielded equivocal findings: 10.4% (55/528) of patients were found to have surgically proven or pathologically proven appendicitis. Sensitivity and specificity of MRI for appendicitis were 96.4% and 98.9%, respectively. Positive and negative predictive values were 91.2% and 99.6%. A normal appendix and abnormalities not involving the appendix were identified on MRI in 21.6% (114/528) of patients. CONCLUSION: Our data show that unenhanced MRI for suspected appendicitis in pediatric patients is clinically effective when performed in a nonpediatric hospital setting with nonpediatric radiologists, emergency physicians, and surgeons.

Unfounded conclusions of equivalence in diagnostic accuracy studies: a pervasive fallacy of inference in pediatric radiology scientific abstracts.

BACKGROUND: In studies of diagnostic performance that fail to detect a statistically significant difference between compared techniques, investigators often declare evidence of equivalence or similarity without having actually tested that assertion due to incorrect methodology or insufficient statistical power. OBJECTIVE: The purpose of our investigation is to measure the prevalence of unfounded assertions of equivalence or similarity in comparison studies presented at the International Pediatric Radiology (IPR) meeting of 2016 and promote awareness of this fallacy of inference to the pediatric radiology community. MATERIALS AND METHODS: Two pediatric radiologists independently reviewed the methodology and reporting quality of the 194 scientific paper abstracts from the 2016 IPR meeting. All comparison studies were identified and those failing to detect a statistically significance difference and making a claim of equivalence or similarity in the results or conclusion were assessed for a description of the study design type, statistical power and sample size estimator calculation. RESULTS: Of 194 scientific paper abstracts, 112 (58%) were comparison studies. Of these, 36/112 (32%) made unfounded inferences of equivalence or similarity in diagnostic imaging performance. No study had an equivalence or non-inferiority design. No abstract specified the statistical power of the study, and only one abstract acknowledged a small sample size as a limitation in detecting a statistically significant difference. CONCLUSION: Inadequate reporting and unfounded inferences of equivalence or similarity were common in diagnostic performance comparison studies presented at IPR 2016. Failure to recognize these limitations could have adverse consequences by leading to the adoption of unvalidated imaging techniques.

Rapid Magnetic Resonance Imaging Evaluation of Femoral Neck Stress Fractures in a U.S. Active Duty Military Population.

OBJECTIVES: Timely diagnosis of femoral neck stress fractures is important to prevent fracture completion and displacement. We hypothesize that an abbreviated magnetic resonance imaging (MRI) hip examination can diagnose femoral neck stress fractures and that femoral neck stress fractures are common in U.S. military recruits. METHODS: We retrospectively reviewed abbreviated hip MRI examinations performed on active duty patients from November 1, 2013, to August 5, 2014. Patients were referred by primary care providers on the basis of high clinical suspicion. Study variables included presence and grade of femoral neck stress fractures. RESULTS: 229 patients were evaluated with an abbreviated hip MRI. 43 patients (18.8%) were diagnosed with femoral neck stress fractures and 12 patients (5.2%) had bilateral femoral neck stress fractures. All femoral neck stress fractures were on the compressive side. Grading of stress fractures was as follows: 0 Grade I (0%), 8 Grade II (14.5%), 32 Grade III (58.2%), and 15 Grade IV (27.2%). CONCLUSIONS: An abbreviated MR hip examination can diagnose femoral neck stress fractures as well as additional pathologies that explain the patient's symptoms. Femoral neck stress fractures are common in U.S. military personnel.

Acute Atrazine Exposure has Lasting Effects on Chemosensory Responses to Food Odors in Crayfish (Orconectes virilis).

The herbicide atrazine is known to impact negatively olfactory-mediated behaviors in aquatic animals. We have shown that atrazine exposure has deleterious effects on olfactory-mediated behavioral responses to food odors in crayfish; however, recovery of chemosensory abilities post-atrazine exposure has not been investigated. We examined whether crayfish (Orconectes virilis) recovered chemosensory abilities after a 96-h exposure to sublethal, environmentally relevant concentrations of 80 ppb (µg/L) atrazine. Following treatment, we analyzed the ability of the crayfish to locate a food source using a Y-maze with one arm containing fish-flavored gelatin and the other containing unflavored gelatin. We compared the time spent in the food arm of the Y-maze, near the food source, as well as moving and walking speed of control and atrazine-treated crayfish. We also compared the number of crayfish that handled the food source and the amount of food consumed. Following 24-, 48-, and 72-h recovery periods in fresh water, behavioral trials were repeated to determine if there was any observable recovery of chemosensory-mediated behaviors. Atrazine-treated crayfish spent less time in the food arm, at the odor source, and were less successful at finding the food odor source than control crayfish for all times tested. Additionally, atrazine-treated crayfish consumed less fish-flavored than control crayfish; however, treatment did not affect locomotion. Overall, we found that crayfish are not able to recover chemosensory abilities 72 h post-atrazine exposure. Because crayfish rely heavily on their chemosensory abilities to acquire food, the negative impacts of atrazine exposure could affect population size in areas where atrazine is heavily applied.

Gadoxetic acid: pearls and pitfalls.

Gadoxetic acid is a hepatocyte-specific magnetic resonance imaging contrast agent with the ability to detect and characterize focal liver lesions and provide structural and functional information about the hepatobiliary system. Knowledge of the pharmacokinetics of gadoxetic acid is paramount to understanding imaging protocol and lesion appearance and facilitates identification and avoidance of undesired effects with use of this intravenous contrast agent. This article reviews the utility of gadoxetic acid in liver and biliary imaging, with emphasis on the hepatobiliary phase.