A Diagnostic Algorithm for Posterior Fossa Tumors in Children: A Validation Study

BACKGROUND AND PURPOSE:Primary posterior fossa tumors comprise a large group of neoplasias with variable aggressiveness and short and long-term outcomes. This study aimed to validate the clinical usefulness of a radiologic decision flow chart based on previously published neuroradiologic knowledge for the diagnosis of posterior fossa tumors in children.MATERIALS AND METHODS:A retrospective study was conducted (from January 2013 to October 2019) at 2 pediatric referral centers, Children''s Hospital of Philadelphia, United States, and Great Ormond Street Hospital, United Kingdom. Inclusion criteria were younger than 18 years of age and histologically and molecularly confirmed posterior fossa tumors. Subjects with no available preoperative MR imaging and tumors located primarily in the brain stem were excluded. Imaging characteristics of the tumors were evaluated following a predesigned, step-by-step flow chart. Agreement between readers was tested with the Cohen κ, and each diagnosis was analyzed for accuracy.RESULTS:A total of 148 cases were included, with a median age of 3.4 years (interquartile range, 2.1–6.1 years), and a male/female ratio of 1.24. The predesigned flow chart facilitated identification of pilocytic astrocytoma, ependymoma, and medulloblastoma sonic hedgehog tumors with high sensitivity and specificity. On the basis of the results, the flow chart was adjusted so that it would also be able to better discriminate atypical teratoid/rhabdoid tumors and medulloblastoma groups 3 or 4 (sensitivity = 75%–79%; specificity = 92%–99%). Moreover, our adjusted flow chart was useful in ruling out ependymoma, pilocytic astrocytomas, and medulloblastoma sonic hedgehog tumors.CONCLUSIONS:The modified flow chart offers a structured tool to aid in the adjunct diagnosis of pediatric posterior fossa tumors. Our results also establish a useful starting point for prospective clinical studies and for the development of automated algorithms, which may provide precise and adequate diagnostic tools for these tumors in clinical practice.

In the past 10 years, there has been an exponential increase in knowledge of the molecular characteristics of pediatric brain tumors, which was only partially incorporated in the 2016 World Health Organization Classification of Tumors of the Central Nervous System.¹ The main update in the 2016 Classification was the introduction of the molecular profile of a tumor as an important factor for predicting different biologic behaviors of entities which, on histology, look very similar or even indistinguishable.² A typical example is the 4 main groups of medulloblastoma: wingless (WNT), sonic hedgehog (SHH) with or without the p53 mutation, group 3, and group 4. Although they may appear similar on microscopy, these categories have distinct molecular profiles, epidemiology, prognosis, and embryologic origin.³Subsequent to the publication of the 2016 World Health Organization Classification, further studies have identified even more molecular subgroups of medulloblastoma with possible prognostic implications⁴ and also at least 3 new molecular subgroups of atypical teratoid/rhabdoid tumor (AT/RT)⁵ and several subgroups of ependymoma.⁶ MR imaging shows promise as a technique for differentiating histologic tumors and their molecular subgroups. This capability relies on not only various imaging characteristics but also the location and spatial extension of the tumor, evident on MR imaging, which can be traced to the embryologic origin of the neoplastic cells.^5,7-10One approach to the challenge of identifying imaging characteristics of different tumors in children is to use artificial intelligence. Yet despite this exciting innovation, correctly identifying the location of the mass and its possible use as an element for differential diagnosis still requires the expertise of an experienced radiologist. Previously, D''Arco et al¹¹ proposed a flow chart (Fig 1) for the differential diagnosis of posterior fossa tumors in children based on epidemiologic, imaging signal, and location characteristics of the neoplasm. The aims of the current study were the following: 1) to validate, in a retrospective, large cohort of posterior fossa tumors from 2 separate pediatric tertiary centers, the diagnostic accuracy of that flow chart, which visually represents the neuroadiologist''s mental process in making a diagnosis of posterior fossa tumors in children, 2) to describe particular types of posterior fossa lesions that are not correctly diagnosed by the initial flow chart, and 3) to provide an improved, clinically accessible flow chart based on the results.Open in a separate windowFIG 1.Predesigned radiologic flow chart created according to the literature before diagnostic accuracy analysis. The asterisk indicates brain stem tumors excluded from the analysis. Double asterisks indicate relative to gray matter. Modified with permission from D''Arco et al.¹¹     

Mortality Rate and Mid-Term Outcomes of Total Hip Arthroplasty Using Dual Mobility Cups for the Treatment of Femoral Neck Fractures in a Middle Eastern Population

Background

The dual mobility cups (DMCs) were shown to reduce dislocation rate following total hip arthroplasty for any etiology, including femoral neck fractures. No reported studies evaluating DMC results for femoral neck fracture in a Middle Eastern population were found in the literature.

Risk factors associated to tobacco and alcohol use in a large French cohort of pregnant women

Archives of Women's Mental Health - Tobacco and/or alcohol use during pregnancy is a major public health concern. The aim of our study was to identify risk factors associated to maternal...     

Realistic Food-Based Approaches Alone May Not Ensure Dietary Adequacy for Women and Young Children in South-East Asia

Objectives Micronutrient deficiencies, in southeast Asia (SE Asia), remain a public health challenge. We evaluated whether promoting the consumption of locally available nutritious foods, which is a low-risk micronutrient intervention, alone can ensure dietary adequacy, for women of reproductive age and 6–23 m old children. Methods Representative dietary data from Cambodia, Indonesia, Lao PDR, Thailand and Vietnam were analysed using linear programming analysis to identify nutrients that are likely low in personal food environments (problem nutrients), and to formulate food-based recommendations (FBRs) for three to six target populations per country. Results The number of problem nutrients ranged from zero for 12–23 m olds in Indonesia, Thailand and Vietnam to six for pregnant women in Cambodia. The FBRs selected for each target population, if adopted, would ensure a low percentage of the population was at risk of inadequate intakes for five to ten micronutrients, depending on the country and target population. Of the 11 micronutrients modelled, requirements for iron, calcium and folate were most difficult to meet (≥ 10 of the 24 target populations), using FBRs alone. The number of individual FBRs selected per set, for each target population, ranged from three to eight; and often included meat, fish or eggs, liver/organ meats, vegetables and fruits. Conclusions for practice Intervention strategies need to increase access to nutritious foods, including products fortified with micronutrients, in SE Asia, when aiming to ensure dietary adequacy for most individuals in the population.

     

Enumeration of oral streptococci on media containing different concentrations of sodium and potassium ions

Laboratory "type" strains of oral streptococci were screened for their ability to grow on mitis-salivarius agar (MSA) in the presence of increasing concentrations of either Na+ or K+ up to 500 mmol/L. Strains were generally better able to withstand increasing concentrations of Na+ than K+, although low numbers of colony-forming units (cfus) were seen with the highest concentration of either cation. Two strains of Streptococcus mutans, Ingbritt 162 and Ingbritt 175, behaved differently when the concentration of cation was increased from 50 to 200 mmol/L; the latter showed a marked increase in the number of cfus when the Na+ concentration was increased from 50 to 200 mmol/L, whereas there was a decrease with strain Ingbritt 162. Strains of oral streptococci from the saliva of adults and children were isolated on modified MSA containing known concentrations of Na+ and K+ and further examined if they showed "mutans-like" colony morphology. The number of cfus generally dropped as the concentration of Na+ or K+ was increased from 200 to 350 or 500 mmol/L. Greater numbers of streptococci were tolerant to Na+ than to K+. Half of the isolates were members of the Streptococcus sanguis group (SSG), either Streptococcus mitis or S. sanguis II, and these were more tolerant to high concentrations of Na+ or K+ than other isolates that were identified as Streptococcus morbillorum, Streptococcus acidominimus, and Streptococcus milleri.     

Molecular biological techniques and their use to study streptococci in dental caries

This review explains some of the basic techniques of molecular biology and their application to the study of oral streptococci. Examples of how these techniques have furthered the understanding of streptococcal colonization in health and disease are discussed along with approaches to controlling dental caries that have been made plausible by the knowledge gained using these techniques.     

Microtensile bond strength of light- and self-cured adhesive systems to intraradicular dentin using a translucent fiber post

This study evaluated the bond strength of a light- and self-cured adhesive system to different intraradicular dentin areas (cervical, middle and apical thirds). Twenty single-rooted teeth were instrumented and their roots were prepared to receive a #2 translucent fiber post (Light Post). The root canals were irrigated with 0.5% sodium hypochlorite for one minute, rinsed with water and dried using paper tips. The teeth were divided into two groups (n=10): Single Bond [SB] (light-cured) and Scotchbond Multi-Purpose Plus [SBMP] (self-cured). To avoid polymerization of the materials through the root lateral walls, the teeth were placed in a silicone mold and the adhesives applied with a thin microbrush according to manufacturer's instructions. The resin cement, Rely X ARC, was inserted into the root canals using Lentulo burs. The post was then placed and the light-curing procedure was carried out for 40 seconds (+/-500 mW/cm2). The roots were kept in a 100% relative moisture environment for 24 hours and stored in distilled water for an additional 24 hours. Each root was perpendicularly sectioned into 1-mm thick sections, resulting in approximately four slices per region. Dumbbell-shaped slices were obtained by trimming the proximal surfaces of each slice using a diamond bur until it touched the post. The bonded area was calculated, slices were attached to a special device and submitted to microtensile testing at 1 mm/minute crosshead speed. Data were analyzed using ANOVA and Tukey's test. The mean bond strength values (MPa) were: SBMP: cervical=10.8a, middle=7.9b%, apical=7.1bc; SB: cervical=8.1b, middle=6.0c, apical=6.9b. Significant differences were found between adhesive systems only for the cervical third. The cervical region showed higher mean bond strength values than the middle and apical regions (p<0.0001).     

Fasting plasma homocysteine levels in the insulin resistance syndrome: the Framingham offspring study

OBJECTIVE: Insulin resistance, associated metabolic abnormalities, and elevated homocysteine levels are risk factors for cardiovascular disease (CVD). We examined relationships between homocysteine levels and features of insulin resistance syndrome (IRS). RESEARCH DESIGN AND METHODS: We measured clinical characteristics, plasma levels of fasting homocysteine, folate, B vitamins, creatinine, and fasting and 2-h insulin and glucose levels after a 75-g oral glucose tolerance test in 2,214 subjects without CVD at the fifth examination (1991-1995) of the Framingham Offspring Study. After excluding 203 subjects with diabetes, the remaining 2,011 subjects were categorized as having none, one, two, or all three of the phenotypes of IRS: impaired glucose tolerance, hypertension, and/or a central metabolic syndrome (two or more traits: obesity, dyslipidemia, or hyperinsulinemia). In addition, in 1,592 subjects attending the sixth examination (1995-1998), we measured the urine albumin/creatinine ratio (UACR). Age-, sex-, creatinine-, vitamin-, and UACR-adjusted mean homocysteine levels or proportions with homocysteine >14 micromol/l in each phenotypic category and differences between categories were assessed with regression models. RESULTS: The mean age of the subjects was 54 years (range 28-82); 55% were women, 12.3% had hyperinsulinemia, and 15.9% had two or more of the IRS phenotypes. Adjusted mean homocysteine levels were higher comparing those with hyperinsulinemia (9.8 micromol/l) and those without (9.4 micromol/l, P = 0.04) and were higher among subjects with two or more IRS phenotypes (9.9 micromol/l) compared with those with 1 or no phenotype (9.3 micromol/l, P = 0.003). Mean UACR levels were also higher among subjects with two or more IRS phenotypes (7.2 mg/g) compared with those with 1 or no phenotype (5.5 mg/g, P = 0.007). CONCLUSIONS: Hyperhomocysteinemia and abnormal urinary albumin excretion are both associated with hyperinsulinemia and may partially account for increased risk of CVD associated with insulin resistance. Because hyperhomocysteinemia and microalbuminuria also reflect endothelial injury, these observations also support the hypothesis that endothelial dysfunction is associated with expression of the IRS.