Benefits of diffusion-weighted imaging in pediatric acute osteoarticular infections.

BACKGROUND: Contrast-enhanced magnetic resonance imaging (MRI) is recommended for the diagnosis of acute osteoarticular infections in children. Diffusion-weighted imaging (DWI) may be an alternative to the injection of gadolinium. OBJECTIVE: To evaluate unenhanced MRI with DWI in comparison to contrast-enhanced MRI for the diagnostic work-up of acute osteoarticular infections in children. MATERIALS AND METHODS: This retrospective study included 36 children (age range: 7 months-12 years) with extra-spinal osteoarticular infections and MRI performed within 24 h of admission. MRI protocol included short tau inversion recovery (STIR), water-only T2 Dixon, T1, DWI, and gadolinium-enhanced T1 sequences. Two readers reviewed three sets of images: 1) unenhanced sequences, 2) unenhanced sequences with DWI and 3) unenhanced followed by contrast-enhanced sequences (reference standard). Sensitivity and specificity of sets 1 and 2 were compared to set 3 and assessed to identify osteoarticular infections: osteomyelitis (long bones, metaphyseal equivalents), septic arthritis and abscess (soft tissues, bone). RESULTS: All 14 cases of osteomyelitis in the metaphyses and diaphyses of long bones and all 27 cases of septic arthritis were identified by unenhanced sequences, but 4/16 abscesses were missed. For the diagnosis of abscess, DWI increased sensitivity to 100%. Among the 18 osteomyelitis in metaphyseal equivalents, 4 femoral head chondroepiphyses were identified by contrast-enhanced sequences only. CONCLUSION: MRI for suspected pediatric acute osteoarticular infections is the best diagnostic modality to guide patient management. An unenhanced protocol with DWI may be an alternative to a contrast-based protocol, even in the presence of an abscess. However, gadolinium remains necessary to assess for chondroepiphyseal involvement of the femoral head.

Acoustic radiation force impulse imaging: normal values of spleen stiffness in healthy children.

BACKGROUND: Acoustic radiation force impulse (ARFI) imaging is a noninvasive ultrasound elastography technique for evaluating tissue stiffness. The association of liver and spleen stiffness provides additional information in the assessment of portal hypertension. The technique and normal values of spleen stiffness by point shear wave elastography (p-SWE) in pediatrics have not been well documented. OBJECTIVE: Our aim is to describe the feasibility and normal ARFI elastography values in the spleen for healthy children and to compare measurements in two different probe positions (the axial and sagittal planes). MATERIALS AND METHODS: Spleen p-SWE using ARFI values were measured with a 6C1 probe in 102 healthy children (age range: 8 weeks to 17 years) divided into four age groups. An average of nine (standard deviation: two) spleen stiffness measurements were taken during free breathing in each plane (axial and sagittal). The impact of age and measurement plane in the spleen was analyzed using multivariate models. RESULTS: There was no significant difference in spleen stiffness values taken at different ages, with an average of the medians of 2.43±0.31 m/s. There was no significant difference based on probe orientation: sagittal plane (median: 2.46±0.29 m/s) and axial plane (median: 2.43±0.32 m/s) with Student's t-test P=0.18. The mean depth of measurement varied between 2.3 cm and 3.7 cm, according to age. CONCLUSION: Normal spleen stiffness values using ARFI imaging in children do not vary with age and correspond to a median of 2.43 m/s. No significant difference was found when using different probe positions.

Iterative algorithms for metal artifact reduction in children with orthopedic prostheses: preliminary results.

BACKGROUND: Increased computational power allows computed tomography (CT) software to process very advanced mathematical algorithms to generate better quality images at lower doses. One such algorithm, iterative metal artifact reduction (iMAR) has proven to decrease metal artifacts seen in CT images of adults with orthopedic implants. OBJECTIVES: To evaluate artifact reduction capability of the algorithm in lower-dose pediatric CT compared to our routine third-generation advanced modeled iterative reconstruction (ADMIRE) algorithm. MATERIALS AND METHODS: Thirteen children (11-17 years old) with metal implants underwent routine clinically indicated CT. Data sets were reconstructed with an iMAR algorithm. Hounsfield units and image noise were measured in bone, muscle and fat in the streak artifact (near the implant) and at the greatest distance from the artifact (far from the implant). A regression model compared the effects of the algorithm (standard ADMIRE vs. iMAR) near and far from the implant. RESULTS: Near the implant, Hounsfield units with iMAR were significantly different in our standard ADMIRE vs. iMAR for bone, muscle and fat (P<0.001). Noise was significantly different in standard ADMIRE vs. iMAR in bone (P<0.003). Far from the implant, Hounsfield units and noise were not significantly different for ADMIRE vs. iMAR, for the three tissue types. CONCLUSION: These preliminary results demonstrate that iMAR algorithms improves Hounsfield units near the implant and decreases image noise in bone in low-dose pediatric CT. It does this without changing baseline tissue density or noise far from the implant.

A simple, precocious, and reliable way to assess future clinical outcome in children with Perthes disease and mild femoral head involvement: correlation between MRI with diffusion-weighted and dynamic gadolinium-enhanced subtraction and Catterall and Herring classifications.

BACKGROUND: In children older than 5 years with a mild form of Legg-Calvé-Perthes disease, the outcome is difficult to predict. In this study, we retrospectively correlated gadolinium-enhanced subtracted (DGS) and diffusion (DWI) MRI findings to the radiographic assessment according to the Catterall and Herring et al. classifications and to the final score according to Stulberg et al.: the aim was to identify a precocious, simple, and objective criterion to differentiate between forms evolving favourably and forms requiring an early surgical treatment in order to avoid femoral head deformity and subsequent osteoarthritis. METHODS: Twelve boys with unilateral mild femoral head involvement (Catterall grade 2 or grade 3) underwent DSG and DWI MR during the early phase of the disease. The absence of enhancement of the external pillar on DSG MRI and the presence of metaphyseal hyperintensity on DWI were considered to be the signs of poor outcome. These findings were correlated with the Catterall and Herring et al. classifications at the initial sclerotic stage and early fragmentation phase and with the Stulberg et al. classifications at least 5 years after the onset of the disease. RESULTS: DSG MRI findings correctly discriminated three out of four patients with a good outcome but underestimated two out of eight patients with a poor outcome. DWI findings correlated with the Catterall and Herring et al. classifications in 12 out of 12 cases. In only one case, DWI findings did not correlate with the Stulberg et al. classification. CONCLUSION: DWI MR provides an objective and accurate prognostic criterion that is relatively easy to recognise. DGS MR findings are less accurate, thus underestimating the gravity of the disease in one-fourth of the patients with a poor outcome.

Factors influencing the diagnostic yield and accuracy of image-guided percutaneous needle biopsy of pediatric tumors: single-center audit of a 26-year experience.

BACKGROUND: Image-guided percutaneous core needle biopsy is a common procedure for diagnosis of both solid tumors and hematological malignancies in children. Despite recent improvements, a certain rate of non-diagnostic biopsies persists. OBJECTIVE: To assess the factors influencing the diagnostic yield and accuracy of percutaneous core needle biopsies of pediatric tumors. MATERIALS AND METHODS: We conducted a single-center retrospective study of a 26-year experience with image-guided biopsies in children and young adults. Using uni- and multivariate analysis, we evaluated the association of diagnostic yield and accuracy with technical factors (image-guided procedure, pathological technique) and clinical factors (complication rate, histological type and anatomical location). RESULTS: We retrieved data relating to 396 biopsies were performed in 363 children and young adults (mean age: 7.4 years). Overall, percutaneous core needle biopsy showed a diagnostic yield of 89.4% (95% confidence interval [CI] 85.9-92.2) and an accuracy of 90.9% (CI 87.6-93.6) with a complication rate of 2.5% (CI 1.2-4.6).The diagnostic yield increased with the use of advanced tissue assessment techniques (95.7% with immunohistochemistry versus 82.3% without immunohistochemistry; P < 0.0001) and an increased number of passes (mean: 3.96 for diagnostic biopsies versus 3.62 for non-diagnostic biopsies; P = 0.044). CONCLUSION: The use of advanced pathological techniques and an increased number of passes are the two main factors influencing the diagnostic success of biopsies in pediatric tumors.

MCF2 is linked to a complex perisylvian syndrome and affects cortical lamination.

The combination of congenital bilateral perisylvian syndrome (CBPS) with lower motor neuron dysfunction remains unusual and suggests a potential common genetic insult affecting basic neurodevelopmental processes. Here we identify a putatively pathogenic missense mutation in the MCF2 gene in a boy with CBPS. Using in utero electroporation to genetically manipulate cortical neurons during corticogenesis, we demonstrate that the mouse Mcf2 gene controls the embryonic migration of cortical projection neurons. Strikingly, we find that the CBPS-associated MCF2 mutation impairs cortical laminar positioning, supporting the hypothesis that alterations in the process of embryonic neuronal migration can lead to rare cases of CBPS.

Intracranial Hemorrhage and Autoimmune Thrombocytopenia in a Neonate: A Rare "Unpredictable" Event.

Neonatal thrombocytopenia is a rare complication of maternal autoimmune thrombocytopenia, and no maternal predictors of its gravity and potential complications have been identified. Neonatal cerebral hemorrhage, a feared event in the setting of autoimmune thrombocytopenia, is fortunately uncommon, but it can occur in utero or in the perinatal period, with potentially serious consequences. The authors report the case of a boy born to a mother affected by autoimmune thrombocytopenia, who presented with severe thrombocytopenia at birth and developed intracranial hemorrhage despite mild maternal thrombocytopenia at delivery and a prompt preventive treatment of the newborn. Platelet count should be tested at birth in all babies born from mothers with autoimmune thrombocytopenia, irrespective of maternal platelets counts during pregnancy or at delivery, and should be closely monitored during the first days of life. Systematic early and serial cranial ultrasound might be advocated in the setting of neonatal thrombocytopenia.

An unusual radiologic manifestation of hypersensitivity pneumonia.

Hypersensitivity pneumonia is clinically suspected and can be characterized on computed tomography by its pattern of diffuse lung disease, in children, as in adults. However, identifying the diagnosis is not always as simple. We report an organizing pneumonia pattern of hypersensitivity pneumonia that can be seen in adult patients, but has not been reported in the pediatric population.