PET/CT and PET/MR in Soft Tissue Sarcoma: An Update.

Soft tissue sarcomas account for 6%-8% of pediatric cancers. The rhabdomyosarcoma family is the most frequent soft tissue sarcoma in this age group accounting for 3% of pediatric cancers. Rhabdomyosarcomas are high-grade tumors with a high propensity to metastasize. The risk-adapted, multimodal therapeutic approach for rhabdomyosarcomas incorporates a combination of surgery, radiotherapy, and multi-agent cytotoxic chemotherapy. Soft tissue sarcomas other than rhabdomyosarcoma account for 3%-4% of pediatric cancers. The nonrhabdomyosarcoma soft tissue sarcomas include both low-grade and high-grade tumors. While surgery is the mainstay of therapy in most non-rhabdomyosarcoma soft tissue sarcomas, many cases require a multimodal therapeutic approach including radiotherapy and chemotherapy. In North America, most pediatric patients with soft tissue sarcomas are treated in Children's Oncology Group clinical trials. In this article, we will primarily focus on the staging, risk stratification, imaging recommendations, and interpretations in accordance with the Children's Oncology Group trials. We will review the results and recommendations of International Soft Tissue Sarcoma Database Consortium and European trials in relevant sections where they provide complementary guidelines.

Low Pretreatment Bone Mineral Density in Gender Diverse Youth.

Gender diverse adolescents have low pretreatment bone mineral density (BMD), with variable changes in BMD after initiation of gender-affirming treatment. We aimed to assess factors associated with low BMD in gender diverse youth. Sixty-four patients were included in our analysis (73% assigned male at birth). Subtotal whole-body BMD Z-scores were low in 30% of patients, and total lumbar spine BMD Z-scores low in 14%. There was a positive association with body mass index, and no association with vitamin D level. Male sex assigned at birth was associated with lower pretreatment BMD, with lower average BMD Z-scores compared to previous studies.

Emerging Trends in Radionuclide Imaging of Infection and Inflammation in Pediatrics: Focus on FDG PET/CT and Immune Reactivity.

The most common indication for 18F-FDG PET/CT is tumor imaging, which may be performed for initial diagnosis, staging, therapeutic response monitoring, surveillance, or suspected recurrence. In the routine practice of pediatric nuclear medicine, most infectious, inflammatory, and autoimmune processes that are detected on 18F-FDG PET/CT imaging - except for imaging in fever or inflammation of unknown origin - are coincidental and not the main indication for image acquisition. However, interpreting these "coincidental" findings is of utmost importance to avoid erroneously attributing these findings to a neoplastic process. We review the recent literature on fever of unknown origin as well as inflammation of unknown origin in pediatrics and then focus on the 18F FDG PET/CT imaging findings seen in two specific entities with increased immune reactivity: hemophagocytic lymphohistiocytosis syndrome and the immune-related adverse events associated with checkpoint inhibitors. We will subsequently close with two sections highlighting related topics and relevant references for further reading.

Radioiodine treatment of pediatric Graves disease: a multicenter review.

BACKGROUND: There is no standardized approach to iodine-131 (I-131) therapy of hyperthyroidism in pediatric Graves disease. This prevents systematic study of outcomes. OBJECTIVE: To characterize current radioiodine dosing and define therapeutic outcomes at multiple institutions that use ultrasound to measure thyroid size to guide I-131 ablation of Graves disease. MATERIALS AND METHODS: This was a retrospective cohort study conducted at three institutions. The three sites collected demographic data, thyroid volume measured by ultrasound (mL), pre-ablation radioiodine uptake, I-131 activity administered, and outcomes at 6 and 12 months for children younger than 18 years of age treated with I-131 between November 2004 and October 2019. Comparisons of continuous variables were performed using the Mann-Whitney U test. RESULTS: Sixty-nine patients (mean age: 14.5±2.5 years) were included, 59 (85.5%) of whom were female. The mean administered I-131 radioiodine activity was 12.5 mCi (463 MBq) (range: 3.8-29.9 mCi [141-1,106 MBq]). At 6 months post-ablation, 54 (80.5% of 67) patients were hypothyroid, 8 (11.9% of 67) were euthyroid and 5 were hyperthyroid. Two of the five hyperthyroid patients had become euthyroid at 12 months. At 12 months, 1 previously euthyroid patient was hyperthyroid. Administered activity per mL of thyroid tissue adjusted for 24-h uptake was lower (0.18 mCi [6.7 MBq] x %/mL vs. 0.31 mCi [11.5 MBq] x %/mL, P=0.0054) for patients who remained hyperthyroid at 6 months. CONCLUSION: There is substantial variability in administered activity for radioiodine ablation of Graves disease in children. Efforts to standardize practice should start by standardizing administered activity guided by measurement of thyroid size by ultrasound. Our results and those of previous studies suggest the need for administered activities ≥0.25 mCi [9.3 MBq] x %/mL of thyroid tissue.

Hemorrhagic Transformation Following Childhood Cardioembolic Stroke Is Not Increased in Anticoagulated Patients.

OBJECTIVE: To characterize the risk of hemorrhagic transformation following cardioembolic stroke in childhood, and whether anticoagulation impacts that risk. METHODS: Ninety-five children (1 month-18 years) with cardioembolic arterial ischemic stroke between January 1, 2009, and December 31, 2019, at 2 institutions were identified for retrospective chart review. Neuroimaging was reviewed to assess for hemorrhagic transformation. RESULTS: There were 11 cases of hemorrhagic transformation; 8 occurred within 2 days of stroke diagnosis. Risk of hemorrhagic transformation did not differ in patients with and without anticoagulation use (15% vs 9%, estimated risk difference 5%; CI -9%, 19%). Stroke size did not predict hemorrhagic transformation (OR 1.004, 95% CI 0.997, 1.010). Risk of hemorrhagic transformation was higher in strokes that occurred in the inpatient compared with the outpatient setting (16% vs 6%). CONCLUSION: Hemorrhagic transformation occurred in 11% of pediatric cardioembolic ischemic stroke, usually within 2 days of stroke diagnosis, and was not associated with anticoagulation or stroke size.

Management of Pediatric Graves Disease: A Review.

Importance: The incidence of Graves disease (GD) is rising in children, and adequate care of these patients requires a multidisciplinary approach. Whether patients are seen in the context of endocrinology, nuclear medicine, or surgery, it is important to know the nuances of the therapeutic options in children. Observations: Given the rarity of GD in children, it is important to recognize its various clinical presenting signs and symptoms, as well as the tests that may be important for diagnosis. The diagnosis is typically suspected clinically and then confirmed biochemically. Imaging tests, including thyroid ultrasonography and/or nuclear scintigraphy, may also be used as indicated during care. It is important to understand the indications for and interpretation of laboratory and imaging tools so that a diagnosis is made efficiently and unnecessary tests are not ordered. Clinicians should be well-versed in treatment options to appropriately counsel families. There are specific scenarios in which medical therapy, radioactive iodine therapy, or surgery should be offered. Conclusions and Relevance: The diagnosis and treatment of pediatric patients with GD requires a multidisciplinary approach, involving pediatric specialists in the fields of endocrinology, ophthalmology, radiology, nuclear medicine, and surgery/otolaryngology. Antithyroid drugs are typically the first-line treatment, but sustained remission rates with medical management are low in the pediatric population. Consequently, definitive treatment is often necessary, either with radioactive iodine or with surgery, ideally performed by experienced, high-volume pediatric experts. Specific clinical characteristics, such as patients younger than 5 years or the presence of a thyroid nodule, may make surgery the optimal treatment for certain patients.

Cerebral Visual Impairment Characterized by Abnormal Visual Orienting Behavior With Preserved Visual Cortical Activation.

Purpose: Children with cerebral visual impairment (CVI) often have abnormal visual orienting behaviors due to impaired or damaged visual cortex. Alternatively, visual-cortical function is intact but visual information is not transformed downstream into an appropriate oculomotor output (visuomotor dysfunction). We examined visual, anatomic, and oculomotor assessments to distinguish visuomotor dysfunction from CVI associated with severely reduced visual-cortical response. Methods: We reviewed the medical records from children with CVI having abnormal visual orienting behaviors, normal ocular examinations, and born near term. Relevant data were visual evoked potentials (VEPs), Teller card acuity, eye movements recorded by video-oculography (VOG), and neuroimaging (magnetic resonance imaging [MRI]) including diffusion tensor imaging (DTI) tractography. Results: Thirty subjects had visuomotor dysfunction based on a normal VEP; of these 33% had a normal MRI and 67% had white matter abnormalities associated with metabolic disease and/or decreased volume of brain parenchyma. VOG recordings showed smooth pursuit gains were uniformly reduced and saccades were dysmetric but followed the main sequence. Ten subjects had severe CVI based on VEPs at noise levels; visual acuities and MRI findings overlapped those of the visuomotor dysfunction group. Developmental delay, seizures, microcephaly, and hypotonia were common across all groups. All subjects with an abnormal conventional MRI had abnormal metrics on DTI tractography from the occipital lobe. Conclusions: A subset of patients with CVI have abnormal visual orienting behaviors despite a normal VEP (visuomotor dysfunction). A majority have abnormal white matter metrics on tractography suggesting a downstream defect in sensorimotor transformation. Clinically, visuomotor dysfunction is indistinguishable from severe CVI.

Pediatric hyperparathyroidism: review and imaging update.

Hyperparathyroidism, due to increased secretion of parathyroid hormones, may be primary, secondary or tertiary. Most pediatric patients with sporadic primary hyperparathyroidism will be symptomatic, presenting with either end-organ damage or nonspecific symptoms. In younger patients with primary hyperparathyroidism, there is a higher prevalence of familial hyperparathyroidism including germline inactivating mutations of the calcium-sensing receptor genes that result in either neonatal severe hyperparathyroidism or familial hypocalciuric hypercalcemia. Parathyroid scintigraphy and ultrasound are complementary, first-line imaging modalities for localizing hyperfunctioning parathyroid glands. Second-line imaging modalities are multiphase computed tomography (CT) and magnetic resonance imaging. In pediatrics, multiphase CT protocols should be adjusted to optimize radiation dose. Although, the role of these imaging modalities is better established in preoperative localization of hyperfunctioning parathyroid glands in primary hyperparathyroidism, the same principles apply in secondary and tertiary hyperparathyroidism. In this manuscript, we will review the embryology, anatomy, pathophysiology and preoperative localization of parathyroid glands as well as several subtypes of primary familial hyperparathyroidism. While most of the recent imaging literature centers on adults, we will focus on the issues that are pertinent and applicable to pediatrics.

Deep medullary vein engorgement and superficial medullary vein engorgement: two patterns of perinatal venous stroke.

Perinatal venous stroke has classically been attributed to cerebral sinovenous thrombosis with resultant congestion or thrombosis of the small veins draining the cerebrum. Advances in brain MRI, in particular susceptibility-weighted imaging, have enabled the visualization of the engorged small intracerebral veins, and the spectrum of perinatal venous stroke has expanded to include isolated congestion or thrombosis of the deep medullary veins and the superficial intracerebral veins. Congestion or thrombosis of the deep medullary veins or the superficial intracerebral veins can result in vasogenic edema, cytotoxic edema or hemorrhage in the territory of disrupted venous flow. Deep medullary vein engorgement and superficial medullary vein engorgement have characteristic findings on MRI and should be differentiated from neonatal hemorrhagic stroke.

Dual-energy X-ray absorptiometry bone densitometry in pediatrics: a practical review and update.

The assessment of pediatric bone mineral content and density is an evolving field. In this manuscript we provide a practical review and update on the interpretation of dual-energy X-ray absorptiometry (DXA) in pediatrics including historical perspectives as well as a discussion of the recently published 2019 Official Position Statements of the International Society of Clinical Densitometry (ISCD) that apply to children.

Management of Hydrocephalus in Children: Anatomic Imaging Appearances of CSF Shunts and Their Complications.

OBJECTIVE. This article addresses the management of hydrocephalus and the CSF shunts used to treat this entity. CONCLUSION. CSF shunts have a high failure rate. Imaging plays a pivotal role in assessing CSF shunt failure and determining the need for surgical revision. An in-depth knowledge of CSF shunt components, their failure modes, and the corresponding findings on anatomic imaging studies is necessary to ensure timely diagnosis and prevent permanent neurologic damage.

Imaging of Horner syndrome in pediatrics: association with neuroblastoma.

Neuroblastoma is the most common neoplasm associated with pediatric Horner syndrome. The laboratory and imaging evaluation of isolated pediatric Horner syndrome is controversial. We review the literature published in the last several decades and present the rationale for the imaging work-up in this patient cohort.

Complications of CSF Shunts in Pediatrics: Functional Assessment With CSF Shunt Scintigraphy-Performance and Interpretation.

OBJECTIVE. The purpose of this article is to review the performance method and criteria for interpretation of CSF shunt scintigraphy studies. CONCLUSION. Interpretation of CSF shunt scintigraphy studies requires an in-depth understanding of hydrocephalus, the functioning of CSF shunts and their components, and the mechanisms of failure of such devices. Application of strict interpretive criteria when evaluating CSF shunt scintigraphy studies improves diagnostic yield, providing valuable functional information to the neurosurgical team who manages patients with shunted hydrocephalus.

Rapid Magnetic Resonance Imaging of the Spine in Neonates with Spinal Dysraphism.

BACKGROUND: The use of nonsedated T2-weighted Half-Fourier Acquisition Single-shot Turbo spin Echo magnetic resonance imaging (MRI) sequences in screening for spinal cord syrinx in neonates with spinal dysraphism has not been reported in the literature. We sought to review our experience using T2-weighted Half-Fourier Acquisition Single-shot Turbo spin Echo imaging of the spine (i.e., rapid spine MRI) in nonsedated neonates for detecting spinal cord syrinx in neonates with spinal dysraphism. METHODS: We performed a retrospective search of our radiology database for neonates with spinal dysraphism who had rapid spine MRI between May 2017 and February 2020. The images were reviewed in conjunction with clinical findings and standard spine imaging, when available. RESULTS: Thirty studies (in 29 neonates) fulfilled our inclusion criteria. Of the 26 neonates with myelomeningocele, 5 of them (19%) had spinal cord syrinx identified on neonatal rapid spine MRI. An additional 2 patients developed syrinx by 2 years of age. Potential pitfalls identified in interpreting rapid spine MRI include motion artifacts and distinguishing a severe holocord syrinx from a truncated spinal cord. CONCLUSIONS: Rapid spine MRI acquired without sedation or anesthesia may be used as a screening technique to detect spinal cord syrinx in neonates with spinal dysraphism.

Clarifying radiology's role in safety events: a 5-year retrospective common cause analysis of safety events at a pediatric hospital.

BACKGROUND: Common cause analysis of hospital safety events that involve radiology can identify opportunities to improve quality of care and patient safety. OBJECTIVE: To study the most frequent system failures as well as key activities and processes identified in safety events in an academic children's hospital that underwent root cause analysis and in which radiology was determined to play a contributing role. MATERIALS AND METHODS: All safety events involving diagnostic or interventional radiology from April 2013 to November 2018, for which the hospital patient safety department conducted root cause analysis, were retrospectively analyzed. Pareto charts were constructed to identify the most frequent modalities, system failure modes, key processes and key activities. RESULTS: In 19 safety events, 64 sequential interactions were attributed to the radiology department by the patient safety department. Five of these safety events were secondary to diagnostic errors. Interventional radiology, radiography and diagnostic fluoroscopy accounted for 89.5% of the modalities in these safety events. Culture and process accounted for 55% of the system failure modes. The three most common key processes involved in these sequential interactions were diagnostic (39.1%) and procedural services (25%), followed by coordinating care and services (18.8%). The two most common key activities were interpreting/analyzing (21.9%) and coordinating activities (15.6%). CONCLUSION: Proposing and implementing solutions based on the analysis of a single safety event may not be a robust strategy for process improvement. Common cause analyses of safety events allow for a more robust understanding of system failures and have the potential to generate more specific process improvement strategies to prevent the reoccurrence of similar errors. Our analysis demonstrated that the most common system failure modes in safety events attributed to radiology were culture and process. However, the generalizability of these findings is limited given our small sample size. Aligning with other children's hospitals to use standard safety event terminology and shared databases will likely lead to greater clarity on radiology's direct and indirect contributions to patient harm.

PET with 18F-Fluorodeoxyglucose/Computed Tomography in the Management of Pediatric Sarcoma.

The role for PET with fludeoxyglucose F 18 (18F-FDG PET)/computed tomography (CT) in the management of pediatric sarcomas continues to be controversial. The literature supports a role for PET/CT in the staging and surveillance of certain specific pediatric sarcoma subtypes; however, the data are less clear regarding whether PET/CT can be used as a biomarker for prognostication. Despite the interest in using this imaging modality in the management of pediatric sarcomas, most studies are limited by retrospective design and small sample size. Additional data are necessary to fully understand how best to use 18F-FDG PET/CT in pediatric sarcoma management.

Reliability of Measuring Insertion Depth in Cochlear Implanted Infants and Children Using Cochlear View Radiography.

OBJECTIVES: Cochlear implant depth of insertion affects audiologic outcomes and can be measured in adults using plain films obtained in the "cochlear view." The objective of this study was to assess interrater and intrarater reliability of measuring depth of insertion using cochlear view radiography. STUDY DESIGN: Prospective, observational. SETTING: Tertiary referral pediatric hospital. SUBJECTS AND METHODS: Patients aged 11 months to 20 years (median, 4 years; interquartile range [IQR], 1-8 years) undergoing cochlear implantation at our institution were studied over 1 year. Children underwent cochlear view imaging on postoperative day 1. Films were deidentified and 1 image per ear was selected. Two cochlear implant surgeons and 2 radiologists evaluated each image and determined angular depth of insertion. Images were re-reviewed 6 weeks later by all raters. Inter- and intrarater reliability were calculated with intraclass correlation coefficients (ICCs). RESULTS: Fifty-seven ears were imaged from 42 children. Forty-nine ears (86%) had successful cochlear view x-rays. Median angular depth of insertion was 381° (minimum, 272°; maximum, 450°; IQR, 360°-395°) during the first round of measurement. Measurements of the same images reviewed 6 weeks later showed median depth of insertion of 382° (minimum, 272°; maximum, 449°; IQR, 360°-397°). Interrater and intrarater reliability ICCs ranged between 0.81 and 0.96, indicating excellent reliability. CONCLUSIONS: Postoperative cochlear view radiography is a reliable tool for measurement of cochlear implant depth of insertion in infants and children. Further studies are needed to determine reliability of intraoperatively obtained cochlear view radiographs in this population.

Initial treatment of pediatric differentiated thyroid cancer: a review of the current risk-adaptive approach.

Differentiated thyroid cancer in children is a rare disease, accounting for only 1.4% of all pediatric malignancies. The diagnosis, biological behavior and treatment of differentiated thyroid cancer in children is different from that in adults. While there are many unresolved issues regarding approaches to management of differentiated thyroid cancer in the pediatric population, there is near universal consensus that treatment of this disease, which includes total thyroidectomy, central lymph node dissection at the time of initial surgery in those with nodal metastases, and the possible use of iodine-131 radiotherapy, is best performed by specialists including high-volume endocrine surgeons and experts with experience in calculating and administering radioactive iodine in children, when deemed appropriate.

Utility of 18F-FDG PET/CT in Infantile Myofibromatosis.

Infantile myofibromatosis, a rare, nonmalignant disease seen almost exclusively in the pediatric population, can involve skin, muscle, soft tissues, bone, or viscera in either solitary or multicentric pattern. Although nonmalignant, visceral involvement in infantile myofibromatosis is a key prognostic indicator, which is associated with mortality in 75% of patients. Those with pulmonary involvement have a particularly poor outcome. This case illustrates the diagnostic utility of F-FDG PET/CT in defining disease extent in this unusual entity and compares it to other commonly used imaging modalities.