A clinically relevant model of acute respiratory distress syndrome in human-size swine.

Despite over 30 years of intensive research for targeted therapies, treatment of acute respiratory distress syndrome (ARDS) remains supportive in nature. With mortality upwards of 30%, a high-fidelity pre-clinical model of ARDS, on which to test novel therapeutics, is urgently needed. We used the Yorkshire breed of swine to induce a reproducible model of ARDS in human-sized swine to allow the study of new therapeutics, from both mechanistic and clinical standpoints. For this, animals were anesthetized, intubated and mechanically ventilated, and pH-standardized gastric contents were delivered bronchoscopically, followed by intravenous infusion of Escherichia coli-derived lipopolysaccharide. Once the ratio of arterial oxygen partial pressure (PaO2) to fractional inspired oxygen (FIO2) had decreased to <150, the animals received standard ARDS treatment for up to 48 h. All swine developed moderate to severe ARDS. Chest radiographs taken at regular intervals showed significantly worse lung edema after induction of ARDS. Quantitative scoring of lung injury demonstrated time-dependent increases in interstitial and alveolar edema, neutrophil infiltration, and mild to moderate alveolar membrane thickening. This pre-clinical model of ARDS in human-sized swine recapitulates the clinical, radiographic and histopathologic manifestations of ARDS, providing a tool to study therapies for this highly morbid lung disease.

Extracardiac imaging findings in COVID-19-associated multisystem inflammatory syndrome in children.

BACKGROUND: Coronavirus disease 2019 (COVID-19)-associated multisystem inflammatory syndrome in children (MIS-C) is an emerging syndrome that presents with a Kawasaki-like disease and multiorgan damage in children previously exposed to COVID-19. OBJECTIVE: To review the extracardiac radiologic findings of MIS-C in a group of children and young adults with a confirmed diagnosis of MIS-C. MATERIALS AND METHODS: In a retrospective study from April 1, 2020, to July 31, 2020, we reviewed the imaging studies of 47 children and adolescents diagnosed with MIS-C, 25 females (53%) and 22 males (47%), with an average age of 8.4 years (range 1.3-20 years). Forty-five had chest radiographs, 8 had abdominal radiographs, 13 had abdominal US or MRI, 2 had neck US, and 4 had brain MRI. RESULTS: Thirty-seven of 45 (82%) patients with chest radiographs had findings, with pulmonary opacities being the most common finding (n=27, 60%), most often bilateral and diffuse, followed by peribronchial thickening (n=26, 58%). Eight patients had normal chest radiographs. On abdominal imaging, small-volume ascites was the most common finding (n=7, 54%). Other findings included right lower quadrant bowel wall thickening (n=3, 23%), gallbladder wall thickening (n=3, 23%), and cervical (n=2) or abdominal (n=2) lymphadenopathy. Of the four patients with brain MRI, one had bilateral parieto-occipital abnormalities and another papilledema. CONCLUSION: The diagnosis of MIS-C and its distinction from other pathologies should be primarily based on clinical presentation and laboratory evidence of inflammation because imaging findings are nonspecific. However, it should be considered in the setting of bilateral diffuse pulmonary opacities, peribronchial thickening, right lower quadrant bowel inflammation or unexplained ascites in a child presenting with Kawasaki-like symptoms and a history of COVID-19 infection or recent COVID-19 exposure.

Is Intussusception a Middle-of-the-Night Emergency?

OBJECTIVES: Intussusception is the most common abdominal emergency in pediatric patients aged 6 months to 3 years. There is often a delay in diagnosis, as the presentation can be confused for viral gastroenteritis. Given this scenario, we questioned the practice of performing emergency reductions in children during the night when minimal support staff are available. Pneumatic reduction is not a benign procedure, with the most significant risk being bowel perforation. We performed this analysis to determine whether it would be safe to delay reduction in these patients until normal working hours when more support staff are available. METHODS: We performed a retrospective review of intussusceptions occurring between January 2010 and May 2015 at 2 tertiary care institutions. The medical record for each patient was evaluated for age at presentation, sex, time of presentation to clinician or the emergency department, and time to reduction. The outcomes of attempted reduction were documented, as well as time to surgery and surgical findings in applicable cases. A Wilcoxon rank test was used to compare the median time with nonsurgical intervention among those who did not undergo surgery to the median time to nonsurgical intervention among those who ultimately underwent surgery for reduction. Multivariable logistic regression was used to test the association between surgical intervention and time to nonsurgical reduction, adjusting for the age of patients. RESULTS: The median time to nonsurgical intervention was higher among patients who ultimately underwent surgery than among those who did not require surgery (17.9 vs 7.0 hours; P < 0.0001). The time to nonsurgical intervention was positively associated with a higher probability of surgical intervention (P = 0.002). CONCLUSIONS: Intussusception should continue to be considered an emergency, with nonsurgical reduction attempted promptly as standard of care.

Estimating Effective Dose of Radiation From Pediatric Cardiac CT Angiography Using a 64-MDCT Scanner: New Conversion Factors Relating Dose-Length Product to Effective Dose.

OBJECTIVE: The purpose of this study is to determine the conversion factors that enable accurate estimation of the effective dose (ED) used for cardiac 64-MDCT angiography performed for children. MATERIALS AND METHODS: Anthropomorphic phantoms representative of 1- and 10-year-old children, with 50 metal oxide semiconductor field-effect transistor dosimeters placed in organs, underwent scanning performed using a 64-MDCT scanner with different routine clinical cardiac scan modes and x-ray tube potentials. Organ doses were used to calculate the ED on the basis of weighting factors published in 1991 in International Commission on Radiological Protection (ICRP) publication 60 and in 2007 in ICRP publication 103. The EDs and the scanner-reported dose-length products were used to determine conversion factors for each scan mode. The effect of infant heart rate on the ED and the conversion factors was also assessed. RESULTS: The mean conversion factors calculated using the current definition of ED that appeared in ICRP publication 103 were as follows: 0.099 mSv · mGy-1 · cm-1, for the 1-year-old phantom, and 0.049 mSv · mGy-1 · cm-1, for the 10-year-old phantom. These conversion factors were a mean of 37% higher than the corresponding conversion factors calculated using the older definition of ED that appeared in ICRP publication 60. Varying the heart rate did not influence the ED or the conversion factors. CONCLUSION: Conversion factors determined using the definition of ED in ICRP publication 103 and cardiac, rather than chest, scan coverage suggest that the radiation doses that children receive from cardiac CT performed using a contemporary 64-MDCT scanner are higher than the radiation doses previously reported when older chest conversion factors were used. Additional up-to-date pediatric cardiac CT conversion factors are required for use with other contemporary CT scanners and patients of different age ranges.

Feed and Wrap MRI Technique in Infants.

The feed and wrap technique refers to the use of feeding and swaddling to induce natural sleep in infants. It can be used prior to an magnetic resonance imaging (MRI) scan, avoiding sedation or anesthesia. We performed a retrospective review of feed and wrap MRI scans in infants 3 months or younger over a 2-year period at our center (279 scans) to evaluate the efficacy of this technique. Of scan results reviewed, 79% addressed the clinical question, 20% partially addressed the clinical question, and 1% were technically inadequate. History of preterm birth (odds ratio [OR] = 2.368; P = .032) and spine MRI (OR = 2.821; P = .001) were associated with a less-successful scan outcome. The feed and wrap technique can be used successfully in infants undergoing MRI; however, it may be less successful in preterm infants and those requiring spinal MRI. A standardized technique performed by experienced personnel may avoid anesthesia and sedation in infants who require MRI.

Value of gadolinium-enhanced MRI in detection of acute appendicitis in children and adolescents.

OBJECTIVE: The aim of this study was to determine both the value of gadolinium-enhanced MRI in children with suspected acute appendicitis and the best sequences for detecting acute appendicitis, to thereby decrease imaging time. MATERIALS AND METHODS: This was a retrospective review of pediatric patients with suspected appendicitis who had undergone MRI at our institution between 2010 and 2011 after an indeterminate ultrasound examination. MRI examinations included T1-weighted unenhanced and contrast-enhanced, T2-weighted, and balanced steady-state free precession (SSFP) sequences in axial and coronal planes. Sequences were reviewed together and individually by five radiologists who were blinded to the final diagnosis. Radiologists were asked to score their confidence of appendicitis diagnosis using a 5-point scale. The diagnostic performance of each MR sequence was obtained by comparing the mean area under the curve (AUC) using receiver operating characteristic (ROC) analysis. RESULTS: A total of 49 patients with clinically suspected appendicitis were included, of whom 16 received a diagnosis of appendicitis. The mean AUCs for reviewing all sequences together, contrast-enhanced sequences alone, T2-weighted sequences alone, and balanced SSFP alone were 0.984, 0.979, 0.944, and 0.910, respectively. No significant difference was observed between reviewing all sequences together versus contrast-enhanced sequences alone (p = 0.90) and T2-weighted sequences alone (p = 0.23). A significant difference was observed between contrast-enhanced sequences and balanced SSFP (p < 0.03). CONCLUSION: Gadolinium-enhanced images and T2-weighted images are most helpful in the assessment of acute appendicitis in the pediatric population. These findings have led to protocol modifications that have reduced imaging time.

Accuracy of plain radiographs to exclude the diagnosis of intussusception.

OBJECTIVES: To prospectively determine the test characteristics of the 3-view abdominal radiograph to decrease the likelihood of ileocolic intussusception. METHODS: We conducted a prospective cross-sectional study of children aged 3 months to 3 years suspected of having intussusception at a children's hospital emergency department. Clinicians obtained supine, prone, and left lateral decubitus radiographs. We determined the presence or absence of intussusception by air enema, ultrasound, operative report, or clinical follow-up. A masked pediatric radiologist reviewed all radiographs. The criteria evaluated were whether air was visualized in the ascending colon on each view and in the transverse colon on the supine view. RESULTS: Nineteen (14.8%) of 128 patients had intussusception. Using air in the ascending colon on all 3 views as the diagnostic criteria, the test characteristics of the 3-view radiograph were sensitivity, 100% (95% confidence interval [CI], 79.1-100); specificity, 17.4% (95% CI, 11.1-26.1); negative predictive value, 100% (95% CI, 79.1-100); and likelihood ratio of a negative test, 0. When 2 or more of 3 views had air in the ascending colon, sensitivity decreased to 89.5% (95% CI, 75.7-100) and specificity improved to 45.0% (95% CI, 35.6-54.3). Air in the transverse colon had moderate sensitivity, 84.2% (95% CI, 67.8-100), but further improved specificity, 63.3% (95% CI, 54.2-72.4). CONCLUSIONS: The presence of air in the ascending colon on the 3-view abdominal radiograph can decrease the likelihood of or exclude intussusception. When clinical suspicion is low, the presence of specific criterion on a 3-view abdominal radiograph series may obviate the need for further studies.

Test characteristics of the 3-view abdominal radiograph series in the diagnosis of intussusception.

OBJECTIVES: To determine the test characteristics of the 3-view abdominal radiograph series to exclude intussusception in children presenting to the pediatric emergency department. METHODS: We performed a single-center retrospective review of children for whom supine, prone, and lateral decubitus abdominal radiographs were performed as part of our standard diagnostic evaluation for intussusception. A pediatric radiologist masked to the patient's clinical data and outcome reviewed all radiographs. The criterion evaluated was whether air was visualized in the ascending colon on each of the 3 radiograph views. We determined the presence or absence of intussusception hierarchically by definitive radiological study report, surgical operative note, or clinical outcome. RESULTS: We analyzed 179 patients, of whom 27 (15.1%) were diagnosed with intussusception. The test characteristics of the 3-view radiograph series in the diagnosis of intussusception when all 3 views had air in the ascending colon were sensitivity of 100% (95% confidence interval [CI] 87-100), specificity of 18.4% (95% CI, 12.3-24.6), likelihood ratio for a negative test of 0 (95% CI, 0.01-1.53), and negative predictive value (NPV) of 100% (lower bound 95% CI, 98%). When at least 2 views had air in the ascending colon, the test characteristics were sensitivity of 96.3% (95% CI, 89.2-100), specificity of 41.4% (95% CI, 33.6-49.3), likelihood ratio for a negative test of 0.09 (0.01-0.62), and NPV of 98.4 (95% CI, 95.2-100). CONCLUSIONS: Using specific criteria, the presence of air in the ascending colon on 2 or 3 abdominal radiograph views has the potential to substantially decrease the likelihood of or exclude intussusception.

New automated fluoroscopic systems for pediatric applications.

Pediatric patients are at higher risk to the adverse effects from exposure to ionizing radiation than adults. The smaller sizes of the anatomy and the reduced X-ray attenuation of the tissues provide special challenges. The goal of this effort is to investigate strategies for pediatric fluoroscopy in order to minimize the radiation exposure to these individuals, while maintaining effective diagnostic image quality. Modern fluoroscopy systems are often entirely automated and computer controlled. In this paper, various selectable and automated modes are examined to determine the influence of the fluoroscopy parameters upon the patient radiation exposures and image quality. These parameters include variable X-ray beam filters, automatic brightness control programs, starting kilovolt peak levels, fluoroscopic pulse rates, and other factors. Typical values of radiation exposure rates have been measured for a range of phantom thicknesses from 5 cm to 20 cm of acrylic. Other factors that have been assessed include spatial resolution, low contrast discrimination, and temporal resolution. The selection menu for various procedures is based upon the examination type, anatomical region, and patient size. For pediatric patients, the automated system can employ additional filtration, special automatic brightness control curves, pulsed fluoroscopy, and other features to reduce the patient radiation exposures without significantly compromising the image quality. The benefits gained from an optimal selection of automated programs and settings for fluoroscopy include ease of operation, better image quality, and lower patient radiation exposures.

Non-immune hydrops and superior vena cava syndrome due to diaphragmatic hernia in one twin.

BACKGROUND: In a monochorionic twin gestation, hydrops in one fetus often results from placental transfusion, accompanied by intrauterine growth restriction (IUGR) of the non-hydropic fetus. CASE: A 35-year-old G11P9 presented with hydrops and IUGR of one of a monochorionic-diamniotic gestation. Extensive testing failed to reveal etiology for hydrops. The patient was delivered at 30 weeks gestation after non-reassuring fetal monitoring. The hydropic baby could not be adequately ventilated and expired in the early post-partum period. A diagnosis of superior vena cava syndrome and pulmonary hypoplasia secondary to right-sided congenital diaphragmatic hernia (CDH) was made neonatally. CONCLUSION: Right-sided CDH can be difficult to diagnose by sonography at times because of the echogenic similarity of liver and lung, and may be suspected from signs of pericardial effusion and ascites.

Pediatric high KV/filtered airway radiographs: comparison of CR and film-screen systems.

The imaging of pediatric airways presents a challenge because of the superimposition of the airway over the bone of the spine on the AP view. In recent years, some radiology departments have replaced conventional X-ray films by computed radiography (CR). The effect of the various changes upon image quality and radiation doses has not been clearly demonstrated. The goal of this paper was to investigate and identify potential improvements and/or degradations to pediatric airways imaging from the application of new technology, in particular to high KV/filtered radiographs; a new filter was designed. Two modern film-screen combinations and a CR system were evaluated for a range of tube potentials from 60 to 140 kVp. The spatial resolutions were measured for different geometrical magnifications. Relative radiation doses were also determined. Clinical airway images of children taken with the different imaging methods were subjectively compared. Our study confirmed that the visualization of the pediatric airways is enhanced by using high X-ray tube potentials with proper X-ray beam filtration. For CR systems, the selection of the cassette size, cassette type, focal spot, and geometrical magnification impact upon the image quality. Despite the increased dynamic range and image processing advantage with CR systems, CR techniques need to be improved to be more comparable with high kVp filtered magnification radiographs using film screens and small X-ray tube focal spots. With appropriate X-ray beam filtration and high kVp's, CR image receptors can provide adequate image quality for pediatric airway imaging. However, the transition to digital radiography involves certain caveats. In general, radiation doses with CR systems are greater than typical doses with film-screen systems.