Feasibility of and experience using a portable MRI scanner in the neonatal intensive care unit.

OBJECTIVE: A portable, low-field MRI system is now Food and Drug Administration cleared and has been shown to be safe and useful in adult intensive care unit settings. No neonatal studies have been performed. The objective is to assess our preliminary experience and assess feasibility of using the portable MRI system at the bedside in a neonatal intensive care unit (NICU) at a quaternary children's hospital. STUDY DESIGN: This was a single-site prospective cohort study in neonates ≥2 kg conducted between October and December 2020. All parents provided informed consent. Neonates underwent portable MRI examination in the NICU with support equipment powered on and attached to the neonate during the examination. A paediatric radiologist interpreted each portable MRI examination. The study outcome variable was percentage of portable MRI examinations completed without artefacts that would hinder diagnosis. Findings were compared between portable MRI examinations and standard of care examinations. RESULTS: Eighteen portable, low-field MRI examinations were performed on 14 neonates with an average age of 29.7 days (range 1-122 days). 94% (17 of 18) of portable MRI examinations were acquired without significant artefact. Significant intracranial pathology was visible on portable MRI, but subtle abnormalities were missed. The examination reads were concordant in 59% (10 of 17) of cases and significant pathology was missed in 12% (2 of 17) of cases. CONCLUSION: This single-centre series demonstrated portable MRI examinations can be performed safely with standard patient support equipment present in the NICU. These findings demonstrate that portable MRI could be used in the future to guide care in the NICU setting. TRIAL REGISTRATION NUMBER: NCT04629469.

Feasibility and acceptability of a diagnostic randomized clinical trial of bowel ultrasound in infants with suspected necrotizing enterocolitis.

We conducted a pilot diagnostic randomized clinical trial (RCT) to examine the feasibility, acceptability, and preliminary outcomes of adding bowel ultrasound (BUS) to the diagnostic evaluation for necrotizing enterocolitis (NEC). Infants ≤ 32 weeks' gestational age with NEC concern were randomized to undergo abdominal X-ray (AXR) or AXR + BUS. The primary outcome was study feasibility. Secondary outcomes included rates of NEC diagnosis and duration of treatment with bowel rest and antibiotics. A total of 56 infants were enrolled; 16 developed NEC concern and were randomized. Rates of recruitment (56/82 = 68%), retention (16/16 = 100%), and protocol compliance (126/127 = 99%) met pre-specified thresholds for feasibility. No significant differences in rates of NEC diagnosis were found between the two groups. Durations of bowel rest and antibiotic treatment were also similar.   Conclusion: Our study supports the feasibility of conducting a definitive diagnostic RCT to establish safety and efficacy of BUS for NEC.   Clinical trial registration: The study was registered at https://clinicaltrials.gov (NCT03963011). What is Known: • Bowel ultrasound (BUS) is increasingly being utilized as an adjunct to abdominal radiographs in evaluating for necrotizing enterocolitis (NEC). • The impact of BUS on patient outcomes is unknown. What is New: • A diagnostic randomized controlled trial study design to determine safety and effectiveness of adding BUS to NEC evaluation is feasible and acceptable.

Are body surface area based estimates of liver volume applicable to children with overweight or obesity? An in vivo validation study.

The liver is the primary organ responsible for clearing most drugs from the body and thus determines systemic drug concentrations over time. Drug clearance by the liver appears to be directly related to organ size. In children, organ size changes as children age and grow. Liver volume has been correlated with body surface area (BSA) in healthy children and adults and has been estimated by functions of BSA. However, these relationships were derived from "typical" populations and it is unknown whether they extend to estimations of liver volumes for population "outliers," such as children with overweight or obesity, who today represent one-third of the pediatric population. Using computerized tomography or magnetic resonance imaging, this study measured liver volumes in 99 children (2-21 years) with normal weight, overweight, or obesity and compared organ measurements with estimates calculated using an established liver volume equation. A previously developed equation relating BSA to liver volume adequately estimates liver volumes in children, regardless of weight status.

Pediatric Esophageal Foreign Body: Possible Role for Digital Tomosynthesis.

OBJECTIVES: Foreign body (FB) ingestion is a common reason for emergency department visits, affecting more than 80,000 children in the United States annually. Whereas most ingested FBs are coins or other radiopaque objects, some are radiolucent FBs such as food. Digital tomosynthesis (DTS) is a radiographic technique that produces cross-sectional images with in-plane resolution similar to that of traditional radiographs. Our pilot study evaluated the sensitivity and specificity of DTS to detect FB in comparison to esophagram and clinical impression. METHODS: This was a retrospective review on patients aged 0 to 18 years with suspected esophageal FB who received an esophagram with DTS at our institution between January 2014 and June 2016. Digital tomosynthesis images were analyzed by 3 readers for identification of FB impaction and compared with esophagram and discharge diagnosis. This study was approved by our local institutional review board. RESULTS: A total of 17 patients underwent an esophagography with DTS for suspected esophageal FB, of which 9 (53%) were suspected of having an FB on esophagram. Compared with esophagram, DTS had a sensitivity of 44%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 62%. Compared with clinical impression, DTS had a sensitivity of 33%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 38%. CONCLUSIONS: This pilot study showed that chest DTS has a very high positive predictive value, compared with esophagram and clinical impression, in detecting radiolucent esophageal FBs in children. Chest DTS is a promising modality for ruling in the presence of a radiolucent esophageal FB.

Using liver elastography to diagnose sinusoidal obstruction syndrome in pediatric patients undergoing hematopoetic stem cell transplant.

Sinusoidal obstruction syndrome (SOS) is a potentially fatal complication of hematopoietic stem cell transplantation (HSCT). Traditional ultrasound (US) has poor sensitivity and specificity. US shear wave elastography (SWE) is a newer technology that measures liver stiffness. This is a single-institution, prospective cohort study evaluating SWE in patients younger than 21 years who received HSCT from December 2015 through June 2017. SOS was defined using the modified Seattle criteria. Subjects had US with SWE at three scheduled time points. t-tests were used to assess for difference between the groups and ROC curves were generated. Twenty-five patients were included. Five subjects developed SOS. At day +5 HSCT, SOS patients had SWE velocities that increased by 0.25 ± 0.21 m/s compared to 0.02 ± 0.18 in patients without SOS (p = 0.020). At day +14, SOS patients had SWE velocities that significantly increased by 0.91 m/s ± 1.14 m/s compared to 0.03 m/s ± 0.23 m/s in patients without SOS (p = 0.010). SWE SOS diagnosis occurred on average 9 and 11 days before clinical and conventional US diagnosis, respectively. Patients who develop SOS have increased liver stiffness compared to patients who do not develop SOS. SWE changes occur before other imaging and clinical findings of SOS.

Spectral Doppler Ultrasound Can Help Diagnose Children With Hepatic Sinusoidal Obstructive Syndrome After Hematopoietic Stem Cell Transplantation.

BACKGROUND: Hepatic sinusoidal obstruction syndrome (SOS) is a potentially fatal complication after hematopoietic stem cell transplantation (HSCT). Current clinical guidelines state that spectral Doppler changes occur late in the disease, and imaging is only useful for confirming SOS diagnosis. OBJECTIVE: Our primary objective was to examine abdominal ultrasound variables as predictors of development of SOS in pediatric HSCT patients. MATERIALS AND METHODS: A single-center cohort retrospective study was conducted on patients aged 0 to 21 years who underwent HSCT between September 2001 and May 2017 at our institution. Patients were excluded if they did not have abdominal ultrasounds after HSCT. Clinical, demographic, grayscale, and spectral Doppler liver ultrasound findings were evaluated. We modeled the odds of SOS diagnosis within 100 days after HSCT as a function of each of the 15 ultrasound variables. RESULTS: A total of 333 patients received an HSCT. One hundred forty subjects had ultrasound data available. Thirty-two patients developed SOS, and 9 of these patients died. Sinusoidal obstruction syndrome odds more than double per 1-SD increase in peak systolic velocity in common hepatic artery or left hepatic artery and more than triple per 1-SD decrease in main portal vein velocity or change in ascites severity. Several ultrasound variables were statistically significant predictors in the Cox models for time to SOS diagnosis. CONCLUSION: Several ultrasound variables can be used as predictors for a patient's risk of developing SOS. The strongest predictors are ascites severity, main portal vein velocity, common hepatic artery peak systolic velocity, and left hepatic artery peak systolic velocity.

Identification of aspirated radiolucent foreign bodies in the pediatric airway using digital tomosynthesis: a multireader phantom study.

Purpose: Foreign body aspiration is difficult to diagnose because many aspirated foreign bodies are low density or radiolucent. Digital radiographs (DR) are poor at detecting radiolucent foreign bodies. Digital tomosynthesis (DTS) has been shown to be ideally suited for applications where DR is insensitive and the increased dose from computed tomography (CT) is not justified. Our objective was to determine if DTS can be a practical alternative to DR and CT in the diagnosis of foreign body aspiration. Approach: A phantom approximating the densities of a pediatric chest was constructed. Radiolucent foreign bodies were placed in the airways. Seven pediatric radiologists assessed DTS and DR images with and without simulated breathing motion. Two rounds were performed with fixed exposure techniques and then automatic exposure control techniques. Interobserver agreement was evaluated using Fleiss' kappa. Results: DTS and DR images using fixed exposure techniques performed very poorly with accuracies of 42% to 60%. DTS with automatic exposure control techniques increased accuracy to 84% for a stationary phantom, but the accuracy dropped to 70% in a phantom with simulated motion. DTS outperformed DR, with DR accuracies of 60% and 63% for stationary simulations and motion, respectively. Interobserver agreement was poor with Fleiss' kappa of 0.476. Conclusion: DTS is superior to DR for radiolucent foreign body detection. However, the overall accuracy and interobserver agreement are likely too low for this modality to be clinically useful.

Effects of an MRI Try Without program on patient access.

BACKGROUND: Pediatric patients are often sedated for magnetic resonance imaging (MRI) scans to ensure images are of diagnostic quality. However, access time for MRIs requiring sedation is often long due to high patient volumes and limited sedation resources. OBJECTIVE: This study examined the effectiveness of an MRI Try Without sedation program to decrease the wait time for obtaining an MRI while simultaneously ensuring diagnostic-quality images. MATERIALS AND METHODS: A retrospective chart review was performed on subjects who utilized the MRI Try Without program from April 2014 through June 2015 at a dedicated pediatric institution. Child life specialist preparations and access time (i.e. time from exam ordered to exam completed) were recorded in each patient's electronic medical record. MRI images were evaluated for image quality by a pediatric neuroradiologist. RESULTS: A total of 134 patients participated in the MRI Try Without program (mean age: 6.9±1.7 years), all of whom received interventions from a child life specialist. The average number of days between when the order was placed and when the MRI was completed using the MRI Try Without program was 15.4±18.5 days, while the third-available appointment for sedation/anesthesia was 46.2 days (standard deviation [SD]±15.7 days). Nearly all patients received a "good" or "very good" image quality determination (87.3%) and only 5 (3.8%) patients were recommended for repeat examination for diagnostic-quality images. CONCLUSION: Utilization of an MRI Try Without sedation program, with child life specialist interventions, decreased the wait time for obtaining an MRI while still providing diagnostic-quality images.

Ultrasound Elastography Applications in Pediatrics.

Ultrasound is one of the most important imaging modalities in pediatric imaging because of its accessibility, portability, lack of ionizing radiation, and ability to generally perform examinations without need for sedation. Ultrasound elastography can measure the stiffness of various tissues. This review article aims to discuss how ultrasound elastography has performed in evaluating multiple pathologies in the pediatric population. The best studied pediatric applications are in liver diseases such as fibrosis, biliary atresia, and hepatic vascular congestion. Measuring muscle stiffness in cerebral palsy is the most promising pediatric musculoskeletal application, but many other applications are in the early stages of research. Other applications in pediatric small organ imaging have been explored and still need more study before gaining clinical relevance.

Construction of an Anthropomorphic Phantom for Use in Evaluating Pediatric Airway Digital Tomosynthesis Protocols.

Interpretation of radiolucent foreign bodies (FBs) is a common task charged to pediatric radiologists. The use of a motion compensated technique to decrease breathing motion on images would greatly decrease overall exposure to ionizing radiation and increase access to treatment yielding a great impact on clinical care. This study reports on the methodology and materials used to construct an in-house anthropomorphic phantom for investigating image quality in digital tomosynthesis protocols for volumetric imaging of the pediatric airway. Availability and cost of possible substitute materials were considered and simplifying assumptions were made. Two different modular phantoms were assembled in coronal slab layers using materials designed to approximate a one- and three-year-old thorax at diagnostic photon energies for use with digital tomosynthesis protocols such as those offered on GE's VolumeRAD application. Exposures were made using both phantoms with inserted food particles inside an oscillating airway. The goal of the phantom is to help evaluate (1) whether the currently used protocol is sufficient to image the airway despite breathing motion and (2) whether it is not, to find the optimal protocol by testing various commercially available protocols using this phantom. The affordable construction of the pediatric sized phantom aimed at optimizing GE's VolumeRAD protocol for airway foreign body imaging is demonstrated in this study which can be used to test VolumeRAD's ability to image the airways with and without a low-density foreign body within the airways.

Bowel Ultrasound for the Diagnosis of Necrotizing Enterocolitis: A Meta-analysis.

Radiographic evaluation for necrotizing enterocolitis (NEC) often yields nonspecific findings. Bowel ultrasound (BUS) provides additional information beyond that of abdominal radiographs and may be helpful in the diagnosis of NEC in neonates. We systematically reviewed and aggregated existing literature to get a better estimate of diagnostic accuracy of BUS in the diagnosis of NEC. A literature search was performed using PubMed, Embase, and Cumulative Index to Nursing and Allied Health Literature to identify studies in which infants with clinically suspected NEC were evaluated using BUS. Studies that used modified Bell staging criteria as the reference standard were included. Study quality was assessed, and pooled sensitivity and specificity of various BUS findings for diagnosing NEC were determined. Six articles with a total of 462 patients met eligibility and inclusion criteria. There was heterogeneity in BUS findings evaluated across studies. Ultrasound detection of classic signs of NEC (portal venous gas, pneumatosis, and free air) had pooled sensitivities ranging from 0.27 to 0.48 and pooled specificities ranging from 0.91 to 0.99. Bowel wall thinning and absent peristalsis had overall low sensitivity (0.22 and 0.30) but high specificity (0.96 and 0.96) for NEC. Assessment of abdominal fluid, which included ascites and focal fluid collection, also had overall low sensitivity and high specificity (simple ascites: 0.45 and 0.92; focal fluid collection: 0.19 and 0.98). In summary, individual BUS findings have low sensitivity and high specificity for diagnosis of NEC. Bowel ultrasound may be a useful adjunct to plain abdominal radiographs in the evaluation of infants with clinical suspicion of NEC.

Bowel ultrasound for predicting surgical management of necrotizing enterocolitis: a systematic review and meta-analysis.

BACKGROUND: Necrotizing enterocolitis (NEC) is a devastating inflammatory disease of the intestinal tract that represents a significant source of morbidity and mortality in preterm infants. Imaging of the abdomen is valuable for timely diagnosis and close monitoring of disease progression in NEC. Bowel ultrasound (US) is increasingly being recognized as an important imaging tool for evaluating NEC that provides additional detail than plain abdominal radiographs. OBJECTIVE: To identify bowel US findings associated with surgical management or death in infants with NEC. MATERIALS AND METHODS: We searched Embase, PubMed, and the Cumulative Index to Nursing and Allied Health Literature for studies investigating the association between bowel US findings and surgical management or death in NEC. Selected articles were evaluated for quality of study methodology using the Newcastle-Ottawa Scale, and aggregate statistics for odds ratio (OR) and 95% confidence interval were calculated. RESULTS: Of 521 articles reviewed, 11 articles comprising 748 infants were evaluated for quality. Nine of the studies were retrospective and from single-center experiences. Pooled analysis showed that focal fluid collections (OR 17.9, 3.1-103.3), complex ascites (OR 11.3, 4.2-30.0), absent peristalsis (OR 10.7, 1.7-69.0), pneumoperitoneum (OR 9.6, 1.7-56.3), bowel wall echogenicity (OR 8.6, 3.4-21.5), bowel wall thinning (OR 7.11.6-32.3), absent perfusion (OR 7.0, 2.1-23.8), bowel wall thickening (OR 3.9, 2.4-6.1) and dilated bowel (OR 3.5, 1.8-6.8) were associated with surgery or death in NEC. In contrast, portal venous gas (OR 3.0, 0.8-10.6), pneumatosis intestinalis (OR 2.1, 0.9-5.1), increased bowel perfusion (OR 2.6, 0.6-11.1) and simple ascites (OR 0.54, 0.1-2.5) were not associated with surgery or death. CONCLUSION: This meta-analysis identified several bowel US findings that are associated and not associated with surgery or death in NEC. Bowel US may be useful for early identification of high-risk infants with NEC who may benefit from more aggressive treatment, including surgery. Future studies are needed to determine whether the addition of bowel US in NEC evaluation would improve outcomes.