Imaging of pediatric hematopoietic stem cell transplant recipients: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper.

Imaging in hematopoietic stem cell transplantation patients is not targeted at evaluating the transplant per se. Rather, imaging is largely confined to evaluating peri-procedural and post-procedural complications. Alternatively, imaging may be performed to establish a baseline study for comparison should the patient develop certain post-procedural complications. This article looks to describe the various imaging modalities available with recommendations for which imaging study should be performed in specific complications. We also provide select imaging protocols for different indications and modalities for the purpose of establishing a set minimal standard for imaging in these complex patients.

Imaging of pediatric cardiac tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper.

Cardiac tumors in children are rare and the majority are benign. The most common cardiac tumor in children is rhabdomyoma, usually associated with tuberous sclerosis complex. Other benign cardiac masses include fibromas, myxomas, hemangiomas, and teratomas. Primary malignant cardiac tumors are exceedingly rare, with the most common pathology being soft tissue sarcomas. This paper provides consensus-based imaging recommendations for the evaluation of patients with cardiac tumors at diagnosis and follow-up, including during and after therapy.

Pediatric Outpatient Noncontrast Brain MRI: A Time-Driven Activity-Based Costing Analysis at Three U.S. Hospitals.

BACKGROUND. MRI utilization and the use of sedation or anesthesia for MRI have increased in children. Emerging alternative payment models (APMs) require a detailed understanding of the health system costs of performing these examinations. OBJECTIVE. The purpose of this study was to use time-driven activity-based costing (TDABC) to assess health system costs for outpatient noncontrast brain MRI examinations across three children's hospitals. METHODS. Direct costs for outpatient noncontrast brain MRI examinations at three academic free-standing pediatric hospitals were calculated using TDABC. Examinations were categorized as sedated MRI (i.e., sedation or anesthesia), nonsedated MRI, or limited MRI. Process maps were created to describe patient workflows based on input from key personnel and direct observation. Time durations for each process activity were determined; time stamps from retrospective EMR review were used when possible. Capacity cost rates were calculated for resource types within three cost categories (labor, equipment, and space); cost was calculated in a fourth category (supplies). Resources were allocated to each activity, and the cost of each process step was determined by multiplying step-specific capacity costs by the time required for each step. The costs of all steps were summed to yield a base-case total examination cost. Sensitivity analysis for sedated MRI was performed using minimum and maximum time duration inputs for each activity to yield minimum and maximum costs by hospital. RESULTS. The mean base-case cost for a sedated brain MRI examination was $842 (range, $775-924 across hospitals), for a nonsedated brain MRI examination was $262 (range, $240-285), and for a limited brain MRI examination was $135 (range, $127-141). For all examination types, the largest cost category as well as the largest source of difference in cost between hospitals was labor. Sensitivity analysis found that the greatest influence on overall cost at each hospital was the duration of the MRI acquisition. CONCLUSION. The health system cost of performing a sedated MRI examination was substantially greater than that of performing a nonsedated MRI examination. However, the cost of each individual examination type did not vary substantially among hospitals. CLINICAL IMPACT. Health systems operating within APMs can use this comparative cost information for purposes of cost reduction efforts and establishment of bundled prices.

Retrospective cohort comparison between fluoroscopic and radiograph-only exams for evaluation of gastrostomy and gastrojejunostomy tubes.

BACKGROUND: Gastrostomy (G) tube or gastrojejunostomy (GJ) tube checks are radiographic procedures that are frequently ordered to confirm tube positioning. OBJECTIVE: To characterize the sensitivity and specificity of radiograph-only examinations and traditional radiologist-performed fluoroscopy exams for G-tube or GJ-tube malposition and other adverse events detectable by imaging. MATERIALS AND METHODS: We performed a retrospective cohort study at a single tertiary pediatric center that included all subjects who underwent G-tube or GJ-tube checks using fluoroscopy or radiograph-only exams between January 1, 2008, and January 1, 2019. Radiograph-only examinations were defined as checks that consist of frontal and lateral abdominal radiographs after injection of contrast through the G-tube or GJ-tube. Fluoroscopy exams were defined as exams performed by a radiologist in the fluoroscopy suite. Radiology reports were evaluated for reported tube malposition and for other adverse events that are detectable by imaging. Clinical notes from the day of the procedure and longer-term clinical follow-up notes were used as a reference standard for adverse events. The sensitivity and specificity of the two procedures were calculated. RESULTS: A total of 212 exams, including 86 (41%) fluoroscopy exams and 126 (59%) radiograph-only exams, were evaluated. The most common correctly identified adverse event was tube malposition (9 true positives). The most commonly missed adverse event was leakage around the tube (8 false negatives). Fluoroscopy exams had a sensitivity of 100% (6/6; 95% CI: 100%, 100%) and a specificity of 100% (80/80; 95% CI: 100%, 100%) for tube malposition, while radiograph-only exams had 75% sensitivity (3/4; 95% CI: 33%,100%) and 100% specificity (112/112; 95% CI: 100%, 100%). CONCLUSIONS: Fluoroscopy and radiograph-only exams have similar sensitivity and specificity for detecting G-tube or GJ-tube malposition.

Pediatric magnetic resonance angiography: to contrast or not to contrast.

Magnetic resonance (MR) angiography and MR venography imaging with contrast and non-contrast techniques are widely used for pediatric vascular imaging. However, as with any MRI examination, imaging the pediatric population can be challenging because of patient motion, which sometimes requires sedation. There are multiple benefits of non-contrast MR angiographic techniques, including the ability to repeat sequences if motion is present, the decreased need for sedation, and avoidance of potential risks associated with gadolinium administration and radiation exposure. Thus, MR angiography is an attractive alternative to CT or conventional catheter-based angiography in pediatric populations. Contrast-enhanced MR angiographic techniques have the advantage of increased signal to noise. Blood pool imaging allows long imaging times that result in high-spatial-resolution imaging, and thus high-quality diagnostic images. This article outlines the technique details, indications, benefits and downsides of non-contrast-enhanced and contrast-enhanced MR angiographic techniques to assist in protocol decision-making.

Turnaround time and efficiency of pediatric outpatient brain magnetic resonance imaging: a multi-institutional cross-sectional study.

BACKGROUND: Aside from single-center reports, few data exist across pediatric institutions that examine overall MRI turnaround time (TAT) and the determinants of variability. OBJECTIVE: To determine average duration and determinants of a brain MRI examination at academic pediatric institutions and compare the duration to those used in practice expense relative value units (RVUs). MATERIALS AND METHODS: This multi-institutional cross-sectional investigation comprised four academic pediatric hospitals. We included children ages 0 to < 18 years who underwent an outpatient MRI of the brain without contrast agent in 2019. Our outcome of interest was the overall MRI TAT derived by time stamps. We estimated determinants of overall TAT using an adjusted log-transformed multivariable linear regression model with robust standard errors. RESULTS: The average overall TAT significantly varied among the four hospitals. A sedated brain MRI ranged from 158 min to 224 min, a non-sedated MRI from 70 min to 112 min, and a limited MRI from 44 min to 70 min. The most significant predictor of a longer overall TAT was having a sedated MRI (coefficient = 0.71, 95% confidence interval [CI]: 0.66-0.75; P < 0.001). The median MRI scan time for a non-sedated exam was 38 min and for a sedated exam, 37 min, approximately double the duration used by the Relative Value Scale (RVS) Update Committee (RUC). CONCLUSION: We found considerable differences in the overall TAT across four pediatric academic institutions. Overall, the significant predictors of turnaround times were hospital site and MRI pathway (non-sedated versus sedated versus limited MRI).

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.

Non-contrast magnetic resonance angiography/venography techniques: what are my options?

Non-contrast magnetic resonance (MR) angiography and MR venography techniques are gaining popularity for vascular imaging because they are faster, more forgiving and less costly compared with contrast-enhanced MR angiography. Non-contrast MR angiography also avoids gadolinium deposition, which is especially important in imaging children. Non-contrast MR angiography has an array of specific applications for numerous clinical indications. This review summarizes the non-contrast MR angiography methods and their relative advantages and disadvantages. The paper also guides the reader on which technique to consider when determining the optimal imaging modality for each individual patient.

Components of a magnetic resonance imaging system and their relationship to safety and image quality.

Magnetic resonance imaging (MRI) is a powerful diagnostic tool that can be optimized to display a wide range of clinical conditions. An MRI system consists of four major components: a main magnet formed by superconducting coils, gradient coils, radiofrequency (RF) coils, and computer systems. Each component has safety considerations. Unless carefully controlled, the MRI machine's strong static magnetic field could turn a ferromagnetic object into a harmful projectile or cause vertigo and headache. Switching magnetic fields in the gradients evokes loud noises in the scanner, which can be mitigated by ear protection. Gradients also generate varying magnetic fields that can cause peripheral nerve stimulation and muscle twitching. Magnetic fields produced by RF coils deposit energy in the body and can cause tissue heating (with the potential to cause skin burns). In this review, we provide an overview of the components of a typical clinical MRI scanner and its associated safety issues. We also discuss how the relationship between the scanning parameters can be manipulated to improve image quality while ensuring a safe operational environment for the patients and staff. Understanding the strengths and limitations of these parameters can enable users to choose optimal techniques for image acquisition, apply them in clinical practice, and improve the diagnostic accuracy of an MRI examination.

Safety issues related to intravenous contrast agent use in magnetic resonance imaging.

Gadolinium-based contrast agents (GBCAs) have been used to improve image quality of MRI examinations for decades and have an excellent overall safety record. However, there are well-documented risks associated with GBCAs and our understanding and management of these risks continue to evolve. The purpose of this review is to discuss the safety of GBCAs used in MRI in adult and pediatric populations. We focus particular attention on acute adverse reactions, nephrogenic systemic fibrosis and gadolinium deposition. We also discuss the non-GBCA MRI contrast agent ferumoxytol, which is increasing in use and has its own risk profile. Finally, we identify special populations at higher risk of harm from GBCA administration.

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.

Imaging in Hepatic Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome.

Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a potentially life-threatening complication of hematopoietic cell transplantation. Early diagnosis and, subsequently, earlier intervention have been shown to be beneficial to clinical outcomes. Diagnostic criteria from the European Society for Blood and Marrow Transplantation include recommendations on the use of imaging for diagnosis. This review discusses evidence on the use of imaging in the management of VOD/SOS and how imaging biomarkers can contribute to earlier diagnosis/treatment.

Atrophy of skin-draining lymph nodes predisposes for impaired immune responses to secondary infection in mice with chronic intestinal nematode infection.

Intestinal nematodes suppress immune responses in the context of allergy, gut inflammation, secondary infection and vaccination. Several mechanisms have been proposed for this suppression including alterations in Th2 cell differentiation and increased Treg cell suppressive function. In this study, we show that chronic nematode infection leads to reduced peripheral responses to vaccination because of a generalized reduction in the available responsive lymphocyte pool. We found that superficial skin-draining lymph nodes (LNs) in mice that are chronically infected with the intestinal nematode Heligmosomides polygyrus, do not reach the same cellularity as worm-free mice upon subsequent BCG infection in the skin. B cells and T cells, all declined in skin-draining LN of H. polygyrus-infected mice, resulting in LNs atrophy and altered lymphocyte composition. Importantly, anti-helminthic treatment improved lymphocyte numbers in skin-draining LN, indicating that time after de-worming is critical to regain full-scale LN cellularity. De-worming, and time for the skin LN to recover cellularity, also mended responses to Bacille Calmette-Guerin (BCG) in the LN draining the footpad injection site. Thus, our findings show that chronic nematode infection leads to a paucity of lymphocytes in peripheral lymph nodes, which acts to reduce the efficacy of immune responses at these sites.

Inter-rater Reliability of Sacral Ratio Measurements in Patients with Anorectal Malformations.

BACKGROUND: Anorectal malformations (ARMs) are a spectrum of congenital anomalies with varying prognosis for fecal continence. The sacral ratio (SR) is a measure of sacral development that has been proposed as a method to predict future fecal continence in children with ARM. The aim of this study was to quantify the inter-rater reliability (IRR) of SR calculations by radiologists at different institutions. MATERIALS AND METHODS: x-Rays in the anteroposterior (AP) and lateral planes were reviewed by a pediatric radiologist at each of six different institutions. Subsequently, images were reviewed by a single, central radiologist. The IRR was assessed by calculating Pearson correlation coefficients and intraclass correlation coefficients from linear mixed models with patient and rater-level random intercepts. RESULTS: Imaging from 263 patients was included in the study. The mean inter-rater absolute difference in the AP SR was 0.05 (interquartile range, 0.02-0.10), and in the lateral SR was 0.16 (interquartile range, 0.06-0.25). Overall, the IRR was excellent for AP SRs (intraclass correlation coefficient [ICC], 81.5%; 95% confidence interval, 75.1%-86.0%) and poor for lateral SRs (ICC, 44.0%; 95% CI, 29.5%-59.2%). For both AP and lateral SRs, ICCs were similar when examined by the type of radiograph used for calculation, severity of the ARM, presence of sacral or spinal anomalies, and age at imaging. CONCLUSIONS: Across radiologists, the reliability of SR calculations was excellent for the AP plane but poor for the lateral plane. These results suggest that better standardization of lateral SR measurements is needed if they are going to be used to counsel families of children with ARM.

Clinical decision support: practical implementation at two pediatric hospitals.

Clinical decision support has been identified by the United States government as a method to decrease inappropriate imaging exams and promote judicious use of imaging resources. The adoption of this method will be incentivized by requiring appropriate use criteria to qualify for Medicare reimbursement starting in January 2020. While Medicare reimbursement is unlikely to directly impact pediatric imaging because of largely disparate patient populations, insurance providers typically use Medicare to benchmark their reimbursement guidelines. Therefore soon after their adoption these guidelines could become relevant to pediatric imaging. In this article we discuss how pediatric imaging was initially underrepresented in the clinical decision support realm, and how this was addressed by a subcommittee involving both American College of Radiology and Society for Pediatric Radiology members. We also present the experience of implementing clinical decision support software at two standalone pediatric hospitals and summarize the lessons learned from these deployments.

Clinical decision support: the role of ACR Appropriateness Criteria.

Clinical decision support is a way to decrease inappropriate imaging exams and promote judicious use of imaging resources. The adoption of clinical decision support will be incentivized by requiring the use of approved mechanisms to qualify for Medicare reimbursement starting in January 2020. Insurance providers base their reimbursement policies on Medicare, so clinical decision support could soon become relevant to pediatric imaging. We present the process behind the American College of Radiology (ACR) Appropriateness Criteria (a set of appropriate use criteria developed by the ACR) that will form the basis for software that can be used to fulfill the criteria for clinical decision support. For most organizations, this software is expected to be the easiest way to implement clinical decision support. Clinical decision support will affect how providers order imaging exams. This article should help readers understand how clinical decision support is expected to change the practice of the ordering providers, how the ACR Appropriateness Criteria are related to clinical decision support and how the ACR Appropriateness Criteria are developed. This will help the interpreting radiologist better communicate with the referring clinician, including informing the latter about how the clinical decision support software is making decisions.

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.

Digital Tomosynthesis Applications in Pediatric Orthopedic Imaging: A Case Series.

Digital tomosynthesis (DTS) is an emerging technology that provides cross-sectional, three-dimensional imaging similar to computed tomography (CT) at a fraction of the radiation dose and cost. In this article, we describe multiple cases where our pediatric orthopedic surgeons have used DTS imaging to help in clinical management of fracture healing.

The Sonographic Stenosis Index: A New Specific Quantitative Measure of Transplant Hepatic Arterial Stenosis.

OBJECTIVES: This study evaluates the sensitivity and specificity of stenosis index (SI), which accounts for the entire spectral Doppler waveform, to detect significant transplant hepatic arterial stenosis. MATERIALS AND METHODS: In this institutional review board-approved, HIPAA compliant study, we retrospectively analyzed 69 patients who had catheter angiography for suspected transplant hepatic arterial stenosis (THAS) between January 2006 and December 2010; all patients had Doppler ultrasound within 30 days before angiography. Patients with angiographic stenosis requiring intervention were considered positive for THAS. Stenosis index was calculated from each patient's spectral Doppler ultrasound images by obtaining the ratio of the area under the high-frequency signal to low-frequency signal in the spectral Doppler. Resistive index (RI) and pulsatility index (PI) were also calculated. Receiver operator curve analysis was performed and the area under the curve (AUC) was compared among the three metrics. RESULTS: Forty-eight of 69 patients had THAS by angiography requiring intervention; 21patients had no angiographic evidence of THAS. SI was significantly different (P < .001) between patients with THAS (SI = 1.04 ± 0.20) and those without THAS (SI = 1.39 ± 0.30). Stenosis index had an AUC of 0.86 for detecting THAS, which was significantly higher than that from RI (AUC = 0.68, P = .038 for the comparison) and PI (AUC = 0.70, P = .029). For SI < 1.35, the sensitivity for THAS was 94% and specificity was 52%. For RI < 0.5, the sensitivity was 96% and the specificity was 29%. CONCLUSIONS: Stenosis index is more accurate than the resistive index and the pulsatility index for detecting transplant hepatic artery stenosis.

Role of magnetic resonance urography in pediatric renal fusion anomalies.

Renal fusion is on a spectrum of congenital abnormalities that occur due to disruption of the migration process of the embryonic kidneys from the pelvis to the retroperitoneal renal fossae. Clinically, renal fusion anomalies are often found incidentally and associated with increased risk for complications, such as urinary tract obstruction, infection and urolithiasis. These anomalies are most commonly imaged using ultrasound for anatomical definition and less frequently using renal scintigraphy to quantify differential renal function and assess urinary tract drainage. Functional magnetic resonance urography (fMRU) is an advanced imaging technique that combines the excellent soft-tissue contrast of conventional magnetic resonance (MR) images with the quantitative assessment based on contrast medium uptake and excretion kinetics to provide information on renal function and drainage. fMRU has been shown to be clinically useful in evaluating a number of urological conditions. A highly sensitive and radiation-free imaging modality, fMRU can provide detailed morphological and functional information that can facilitate conservative and/or surgical management of children with renal fusion anomalies. This paper reviews the embryological basis of the different types of renal fusion anomalies, their imaging appearances at fMRU, complications associated with fusion anomalies, and the important role of fMRU in diagnosing and managing children with these anomalies.