We investigated the isotropic diffusion coefficient (D') and fractional anisotropy (FA) in white matter (WM) during brain development, using an optimised diffusion-tensor imaging (DTI) method with whole brain coverage in a clinically acceptable time. We images 52 children with no evident neurological abnormality (30 boys, 22 girls aged 1 day-16 years) using high-angle DTI with optimised temporal gradient performance. D' and FA were calculated in 10 regions of interest in white matter. We saw that the age-related reduction in D' and increase in FA follow a mono- or biexponential model in white matter, probably depending on the compactness and myelination rate of the fibre tracts. In contrast to other areas, in which adult values were reached during the third year, there is a trend to continuous increase in FA in all deep white-matter areas, suggesting continuing maturation and organisation of deep tracts not detected on conventional MRI.

BackgroundAntibiotics are overused in children and adolescents with lower respiratory tract infection (LRTI). Serum-procalcitonin (PCT) can be used to guide treatment when bacterial infection is suspected. Its role in pediatric LRTI is unclear.MethodsBetween 01/2009 and 02/2010 we randomized previously healthy patients 1 month to 18 years old presenting with LRTI to the emergency departments of two pediatric hospitals in Switzerland to receive antibiotics either according to a PCT guidance algorithm established for adult LRTI or standard care clinical guidelines. In intention-to-treat analyses, antibiotic prescribing rate, duration of antibiotic treatment, and number of days with impairment of daily activities within 14 days of randomization were compared between the two groups.ResultsIn total 337 children, mean age 3.8 years (range 0.1–18), were included. Antibiotic prescribing rates were not significantly different in PCT guided patients compared to controls (OR 1.26; 95% CI 0.81, 1.95). Mean duration of antibiotic exposure was reduced from 6.3 to 4.5 days under PCT guidance (−1.8 days; 95% CI −3.1, −0.5; P = 0.039) for all LRTI and from 9.1 to 5.7 days for pneumonia (−3.4 days 95% CI −4.9, −1.7; P<0.001). There was no apparent difference in impairment of daily activities between PCT guided and control patients.ConclusionPCT guidance reduced antibiotic exposure by reducing the duration of antibiotic treatment, while not affecting the antibiotic prescribing rate. The latter may be explained by the low baseline prescribing rate in Switzerland for pediatric LRTI and the choice of an inappropriately low PCT cut-off level for this population.Trial RegistrationControlled-Trials.com ISRCTN17057980 ISRCTN17057980

A multidiffusion-tensor model (MDT) is presented containing two anisotropic and one isotropic diffusion tensors. This approach has the ability to detect areas of fiber crossings and resolve the direction of crossing fibers. The mean diffusivity and the ratio of the tensor compartments were merged to one independent parameter by fitting MDT to the diffusion-weighted intensities of a two-point data acquisition scheme. By an F-test between the errors of the standard single diffusion tensor and the more complex MDT, fiber crossings were detected and the more accurate model was chosen voxel by voxel. The performance of crossing detection was compared with the spherical harmonics approach in simulations as well as in vivo. Similar results were found in both methods. The MDT model, however, did not only detect crossings but also yielded the single fiber directions. The FACT algorithm and a probabilistic connectivity algorithm were extended to support the MDT model. Key words: diffusion; DTI; fiber crossings; fiber tracking; multitensorAnisotropy of diffusion in the brain (1) is commonly analyzed by a diffusion tensor (DT) model (2). It is commonly assumed that the principal eigenvector, corresponding to the highest eigenvalue, is aligned along the fiber direction. The direction of this eigenvector has been successfully used for fiber tracking (3-6), which provides unique information about brain structure in vivo (7).Fiber tracking, however, is difficult in brain regions where several fiber bundles are crossing. In these cases, the directions of the principal eigenvectors do not correspond to the fiber directions anymore. The DT in these areas may even have an oblate disk-shape form (8) with an undefined direction of the principle vector. In such cases the common second-order diffusion tensor model is not valid anymore (8 -12). In a voxel with a high amount of isotropic tissue, such as CSF or gray matter, the direction of fibers can also be masked. This could cause errors in the reconstructed fiber trajectories and in connectivity estimation.With high angular resolution DWI measurements (HARDI), i.e., by diffusion encoding along 42-128 optimized directions instead of the six minimum diffusionencoding directions, more accurate and detailed information about diffusion in the brain can be obtained (13-15). Frank applied a spherical harmonics analysis (SH) (9) on HARDI data and was able to detect regions, where common DT models fail and several fiber directions in the same voxel exist. These voxels can be analyzed with a multitensor model (10,16,17) or with a generalized DT (18). Alternatively, Jansons and Alexander (19) introduced a persistent angular structure method (PAS MRI), which employs a maximum entropy method (20). A complex model is required to find multiple fiber directions from HARDI data. Alternatively, more detailed diffusion data measurements, e.g., by Q-space (21,22) or Q-ball (23) experiments, can provide information about fiber directions in crossing regions.The focus of this work was to investigate the p...

Purpose:To assess the combined value of diffusionweighted imaging (DWI) and proton magnetic resonance spectroscopy ( 1 H-MRS) in differentiating medulloblastoma, ependymoma, pilocytic astrocytoma, and infiltrating glioma in a pediatric population. Materials and Methods:A total of 17 children with untreated posterior fossa tumors (seven medulloblastoma, four infiltrating glioma, two ependymoma, and four pilocytic astrocytoma), were investigated with conventional MRI, DWI, and MRS using a single-voxel technique. Within the nonnecrotic tumor core, apparent diffusion coefficient (ADC) values using a standardized region of interest (ROI) were retrieved. Quantification of water signal and analysis of metabolite signals from MRS measurements in the same tumorous area were reviewed using multivariant linear discriminant analysis.Results: Combination of ADC values and metabolites, which were normalized using water as an internal standard, allowed discrimination between the four tumor groups with a likelihood below 1 ϫ 10 -9 . Positive predictive value was 1 in all cases. Tumors could not be discriminated when using metabolite ratios or ADC values alone, nor could they be differentiated using creatine (Cr) as an internal reference even in combination with ADC values. Conclusion:Linear discriminant analysis using DWI and MRS using water as internal reference, fully discriminates the four most frequent posterior fossa tumors in children.

The evolutionarily conserved protein coronin 1 is needed for activating the cyclic AMP signaling pathway in the brain and is important for cognition and behavior.

Rhombencephalosynapsis is a rare congenital abnormality characterised by dorsal fusion of the cerebellar hemispheres, agenesis or hypogenesis of the vermis, fusion of dentate nuclei and superior cerebellar peduncles. We describe 9 children, aged 1.5 to 6 years, with rhombencephalosynapsis. Isolated rhombencephalosynapsis was found in 2 patients, hydrocephalus in 3 children and another 3 children had ventriculomegaly. Additional supratentorial abnormalities were documented in 5 patients. Clinical findings ranged from mild truncal ataxia and normal cognitive abilities to severe cerebral palsy and mental retardation. No correlation between clinical findings and magnetic resonance imaging could be established so far.

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The diagnosis of cerebral venous thrombosis is often difficult both clinically and radiologically and until now there is no method available to predict if brain lesions, detected clinically and using conventional brain imaging methods, may lead to full recovery, as expected in vasogenic edema or ischemic infarcts and even a hematoma. New fast neuroimaging techniques such as diffusion-weighted imaging (DWI) are sensitive to different reasons of changes in local tissular water concentration thus giving further insight into the pathophysiological mechanism as well as prognosis of cerebral venous thrombosis. We report the cases of 18 consecutive patients with a diagnosis of cerebral venous thrombosis based on clinical and imaging criteria. All patients underwent magnetic resonance imaging (MRI) of the brain, which comprised isotropic diffusion-weighted MR. Diffusion-weighted MRI showed positive findings in 17/18 cases. In 7 cases the clot could be directly visualized as an area of hyperintensity in the affected vein on DWI. In 7 cases DWI showed areas of signal loss corresponding to hematomas. In 6 cases DWI showed changes in signal intensity that were more subtle. In 4 cases of superficial venous thrombosis, there were areas of decreased ADC values (0.65–0.79 × 10^–3 mm²/s) whereas in 2 cases of deep venous thrombosis, increased DWI intensities could be found that corresponded to both an increase and a decrease in ADC, corresponding to a coexistence of cytotoxic and vasogenic edemas. Diffusion-weighted MRI can demonstrate directly the presence of an intravenous clot in a select number of patients. It can also demonstrate early ischemic changes, and can differentiate conventional T2-weighted MR areas of cytotoxic from vasogenic edema.