Hee Mang Yoon

Sacrococcygeal teratomas in newborns: a comprehensive review for the radiologists

Sacrococcygeal teratomas are the most common solid tumor in newborn infants. The diagnosis is not difficult in many cases; however, there should be additional information on imaging studies in order to manage those infants properly. Details include histology, morphologic classification, complications such as rupture, bleeding, and mass effects on the adjacent structures. Although imaging features cannot accurately predict the histologic subtypes of the tumors, thorough evaluation of the imaging features can help distinguish malignant tumors from benign tumors. In this article, pathogenesis, histological characteristics, clinical considerations, and morphologic characteristics will be discussed.

Diagnostic Performance of Magnetic Resonance Enterography for Detection of Active Inflammation in Children and Adolescents With Inflammatory Bowel Disease: A Systematic Review and Diagnostic Meta-analysis

Importance Magnetic resonance (MR) enterography has the advantage over other techniques of being noninvasive, lacking ionizing radiation, and demonstrating excellent soft-tissue contrast to evaluate pediatric patients with inflammatory bowel disease (IBD). Objective To evaluate the diagnostic performance of MR enterography for detection of active inflammation in children and adolescents with known or suspected IBD. Data Sources A search of MEDLINE and EMBASE up to January 2, 2017, was performed to identify studies. Search terms included child, pediatric, adolescent, Crohn disease, inflammatory bowel disease, and magnetic resonance enterography. The search was limited to English-language publications. Study Selection Studies evaluating the diagnostic performance of MR enterography for detection of active inflammation in pediatric patients with known or suspected IBD were selected. Two reviewers independently assessed the eligibility of the selected articles. Data Extraction and Synthesis The study was performed and reported in accordance with the PRISMA guidelines. Pooled summary estimates of sensitivity and specificity were calculated using hierarchical logistic regression modeling. Main Outcomes and Measures The diagnostic performance of MR enterography for detection of active inflammation in pediatric patients with known or suspected IBD was the primary outcome. Subgroup analyses and meta-regression were performed. Results Eighteen original articles involving a total of 687 patients were included. The summary sensitivity was 83% (95% CI, 75%-89%), the summary specificity was 93% (95% CI, 90%-95%), and the area under the hierarchical summary receiver operating characteristic curve was 0.95 (95% CI, 0.93-0.97). The Higgins I2 statistics demonstrated substantial heterogeneity in terms of sensitivity (I2 = 84.1%) and specificity (I2 = 68.8%). Based on per-patient analysis, the summary sensitivity was 86% (95% CI, 78%-91%) and specificity was 91% (95% CI, 82%-96%). In meta-regression, among the various potential covariates, scanner manufacturer was associated with study heterogeneity. Conclusions and Relevance Magnetic resonance enterography, which is a noninvasive, radiation-free modality, demonstrates high diagnostic performance in the diagnosis of active inflammation in pediatric patients with IBD, especially at the per-patient level.

Computerized Bone Age Estimation Using Deep Learning Based Program: Evaluation of the Accuracy and Efficiency

OBJECTIVE The purpose of this study is to evaluate the accuracy and efficiency of a new automatic software system for bone age assessment and to validate its feasibility in clinical practice. MATERIALS AND METHODS A Greulich-Pyle method-based deep-learning technique was used to develop the automatic software system for bone age determination. Using this software, bone age was estimated from left-hand radiographs of 200 patients (3-17 years old) using first-rank bone age (software only), computer-assisted bone age (two radiologists with software assistance), and Greulich-Pyle atlas-assisted bone age (two radiologists with Greulich-Pyle atlas assistance only). The reference bone age was determined by the consensus of two experienced radiologists. RESULTS First-rank bone ages determined by the automatic software system showed a 69.5% concordance rate and significant correlations with the reference bone age (r = 0.992; p < 0.001). Concordance rates increased with the use of the automatic software system for both reviewer 1 (63.0% for Greulich-Pyle atlas-assisted bone age vs 72.5% for computer-assisted bone age) and reviewer 2 (49.5% for Greulich-Pyle atlas-assisted bone age vs 57.5% for computer-assisted bone age). Reading times were reduced by 18.0% and 40.0% for reviewers 1 and 2, respectively. CONCLUSION Automatic software system showed reliably accurate bone age estimations and appeared to enhance efficiency by reducing reading times without compromising the diagnostic accuracy.

Cranial Nerve Disorders in Children: MR Imaging Findings.

Cranial nerve disorders are uncommon disease conditions encountered in pediatric patients, and can be categorized as congenital, inflammatory, traumatic, or tumorous conditions that involve the cranial nerve itself or propagation of the disorder from adjacent organs. However, determination of the normal course, as well as abnormalities, of cranial nerves in pediatric patients is challenging because of the small caliber of the cranial nerve, as well as the small intracranial and skull base structures. With the help of recently developed magnetic resonance (MR) imaging techniques that provide higher spatial resolution and fast imaging techniques including three-dimensional MR images with or without the use of gadolinium contrast agent, radiologists can more easily diagnose disease conditions that involve the small cranial nerves, such as the oculomotor, abducens, facial, and hypoglossal nerves, as well as normal radiologic anatomy, even in very young children. If cranial nerve involvement is suspected, careful evaluation of the cranial nerves should include specific MR imaging protocols. Localization is an important consideration in cranial nerve imaging, and should cover entire pathways and target organs as much as possible. Therefore, radiologists should be familiar not only with the various diseases that cause cranial nerve dysfunction, and the entire course of each cranial nerve including the intra-axial nuclei and fibers, but also the technical considerations for optimal imaging of pediatric cranial nerves. In this article, we briefly review normal cranial nerve anatomy and imaging findings of various pediatric cranial nerve dysfunctions, as well as the technical considerations of pediatric cranial nerve imaging. Online supplemental material is available for this article. (©)RSNA, 2016.

Performance of MRI for suspected appendicitis in pediatric patients and negative appendectomy rate: A systematic review and meta‐analysis

To evaluate in pediatric patients the diagnostic performance of magnetic resonance imaging (MRI) for suspected appendicitis and its negative appendectomy rate.

The diagnostic performance of reduced-dose CT for suspected appendicitis in paediatric and adult patients: A systematic review and diagnostic meta-analysis

ObjectiveTo evaluate the diagnostic performance of reduced-dose CT for suspected appendicitis.MethodsA systematic search of the MEDLINE and EMBASE databases was carried out through to 10 January 2017. Studies evaluating the diagnostic performance of reduced-dose CT for suspected appendicitis in paediatric and adult patients were selected. Pooled summary estimates of sensitivity and specificity were calculated using hierarchical logistic regression modelling. Meta-regression was performed.ResultsFourteen original articles with a total of 3,262 patients were included. For all studies using reduced-dose CT, the summary sensitivity was 96 % (95 % CI 93–98) with a summary specificity of 94 % (95 % CI 92–95). For the 11 studies providing a head-to-head comparison between reduced-dose CT and standard-dose CT, reduced-dose CT demonstrated a comparable summary sensitivity of 96 % (95 % CI 91–98) and specificity of 94 % (95 % CI 93–96) without any significant differences (p=.41). In meta-regression, there were no significant factors affecting the heterogeneity. The median effective radiation dose of the reduced-dose CT was 1.8 mSv (1.46–4.16 mSv), which was a 78 % reduction in effective radiation dose compared to the standard-dose CT.ConclusionReduced-dose CT shows excellent diagnostic performance for suspected appendicitis.Key Points• Reduced-dose CT shows excellent diagnostic performance for evaluating suspected appendicitis.• Reduced-dose CT has a comparable diagnostic performance to standard-dose CT.• Median effective radiation dose of reduced-dose CT was 1.8 mSv (1.46–4.16).• Reduced-dose CT achieved a 78 % dose reduction compared to standard-dose CT.

The diagnostic performance of shear-wave elastography for liver fibrosis in children and adolescents: A systematic review and diagnostic meta-analysis

AbstractObjectiveTo assess the diagnostic performance of shear-wave elastography for determining the severity of liver fibrosis in children and adolescents.MethodsAn electronic literature search of PubMed and EMBASE was conducted. Bivariate modelling and hierarchical summary receiver-operating-characteristic modelling were performed to evaluate the diagnostic performance of shear-wave elastography. Meta-regression and subgroup analyses according to the modality of shear-wave imaging and the degree of liver fibrosis were also performed.ResultsTwelve eligible studies with 550 patients were included. Shear-wave elastography showed a summary sensitivity of 81 % (95 % CI: 71–88) and a specificity of 91 % (95 % CI: 83–96) for the prediction of significant liver fibrosis. The number of measurements of shear-wave elastography performed was a significant factor influencing study heterogeneity. Subgroup analysis revealed shear-wave elastography to have an excellent diagnostic performance according to each degree of liver fibrosis. Supersonic shear imaging (SSI) had a higher sensitivity (p<.01) and specificity (p<.01) than acoustic radiation force impulse imaging (ARFI).ConclusionsShear-wave elastography is an excellent modality for the evaluation of the severity of liver fibrosis in children and adolescents. Compared with ARFI, SSI showed better diagnostic performance for prediction of significant liver fibrosis.Key Points• Shear-wave elastography is beneficial for determining liver fibrosis severity in children. • Shear-wave elastography showed summary sensitivity of 81 %, specificity of 91 %. • SSI showed better diagnostic performance than ARFI for significant liver fibrosis.

Whole Body MR Imaging: A Useful Imaging Modality in the Management of Children With Acute Myeloid Leukemia

Micro‐Abstract Children with acute myeloid leukemia suffer from various complications such as chloromas and disseminated infection or inflammation during their illness. As these complications tend to involve locations everywhere in the body, whole body magnetic resonance imaging may be a useful tool in children with acute myeloid leukemia. Introduction: To evaluate the distribution of chloromas using whole body magnetic resonance (MR) imaging in pediatric patients with acute myeloid leukemia (AML) and to assess the clinical role of whole body MR imaging in management of pediatric patients with AML. Materials and Methods: We retrospectively searched pediatric patients (< 18 years old) who were diagnosed with AML and underwent whole body MR imaging during their illness between January 2006 and December 2014. The presence of chloromas was defined as when it was proven pathologically or showed typical imaging features. Nonchloroma lesions that were incidentally detected and were not previously seen on other imaging studies were defined as clinically occult nonchloroma lesions. Results: Sixty‐nine whole body MR scans of 40 patients with AML were included. The musculoskeletal system (42.9%) was the most commonly affected by chloromas. A total of 77 chloromas were identified in 11 (27.5%) of 40 patients. Nine (81.8%) of these 11 patients had 2 or more chloromas. There were 39 (50.6%) unexpected chloromas, which were incidentally detected, in 7 patients. Whole body MR scanning provided additional information regarding 21 clinically occult nonchloroma lesions in this patient population. Conclusion: Chloromas tended to show multiplicity and be present without symptoms. The most common site of involvement was the musculoskeletal system. Whole body MR imaging provided additional information that affected the clinical management of children with AML.

Diagnostic Performance of Ultrasound Elastography for Evaluating Portal Hypertension in Children: A Systematic Review and Meta-analysis: Ultrasound Elastography for Portal Hypertension

To assess the diagnostic performance of ultrasound (US) elastography in evaluating portal hypertension in children and compare the liver and spleen stiffness values between the portal hypertension and control groups.

Diagnostic performance of CT for pediatric patients with suspected appendicitis in various clinical settings: a systematic review and meta-analysis

ObjectiveTo assess the diagnostic performance of CT for pediatric patients with suspected appendicitis in various clinical settings and the proportion of acute appendicitis on final diagnosis among equivocal CT findings.MethodsMEDLINE and EMBASE databases were searched until October 21, 2017, for studies investigating diagnostic performance of CT for acute appendicitis in pediatric patients confirmed by histopathologic findings and/or clinical follow-up. Pooled estimates of sensitivity and specificity were calculated using a hierarchical logistic regression modeling. The proportion of true appendicitis among patients with inconclusive CT results was obtained using fixed and random effects meta-analyses.ResultsTwenty-two articles with 3396 patients were included. The pooled sensitivity and specificity were 95% (95% CI, 93−97%) and 94% (95% CI, 90−96%), respectively, and the area under the hierarchical summary receiver operating characteristic (HSROC) curve was 0.98 (95% CI, 0.96−0.99). Subgroup analyses revealed a comparable diagnostic performance in the low-dose CT group (sensitivity, 97%; specificity, 96%) and the unenhanced group (sensitivity, 95%; specificity, 95%). Other subgroups (publication year, study design, enrolled population, true appendicitis proportion, CT channel number, and slice thickness) also showed good diagnostic performance. Six studies reporting the true appendicitis proportion among patients with equivocal CT findings had pooled proportion of 17% (95% CI, 9−29%).ConclusionsCT showed good performance for suspected appendicitis in pediatric patients under various clinical settings, including in cases with dose reduction or absence of IV contrast. The prevalence of true appendicitis among patients with equivocal appendicitis results on CTs was not low; therefore, clinical attention should not be disregarded in this population.