Partial Rhombencephalosynapsis and Chiari Type II Malformation in a Child: a True Association Supported by DTI Tractography

Partial rhombencephalosynapsis (PRECS) has been recently reported in association with Chiari II (CII). However, its existence as a true malformation is challenged due to the anatomical changes potentially induced by CII. The aim of this report was to investigate the contribution of midbrain/hindbrain tractography in this setting. A 13-year-old boy with a known CII malformation and operated myelomeningocele was referred for brain imaging after a first complex partial seizure. In addition to the classical features of CII, MRI showed partially fused cerebellar hemispheres and multiple supratentorial abnormalities. Diffusion tensor imaging (DTI) color map and tractography showed absent transverse fibers on the midsection of the cerebellum, scarce fibers of the middle cerebellar peduncle (MCP), absence of the middle pontine crossing tract, and fibers running vertically in the medial part of the cerebellum. Vertical mediocerebellar fibers are a feature of classical RECS and the paucity or absence of MCP fibers is mainly described in CII. In our patient, DTI and FT therefore demonstrated structural characteristics of both RECS and CII confirming their potential coexistence and suggesting possible shared embryological pathwa

MRI with fibre tracking in Cogan congenital oculomotor apraxia

Background: Congenital ocular motor apraxia (COMA) occasionally shares with Joubert syndrome (JS) and related disorders (JSRDs) a peculiar malformation, the ‘molar tooth sign' (MTS). In JSRDs, the absence of superior cerebellar peduncles (SCP) decussation is reported. Objective: To investigate whether COMA demonstrates similar abnormal axonal pathways. Materials and methods: Eight healthy age-matched controls, three children with clinical COMA and one child with clinical JSRD underwent examination with a 1.5-T MRI scanner. Diffusion-weighted imaging (DWI), colour-coded fractional anisotropy maps and three-dimensional diffusion tensor imaging (DTI) tractography of the cerebellorubral network were analyzed. Results: On DTI cartography, the ‘red dot' originally supposed to represent the SCP decussation in the midbrain was present in controls as well in those with COMA but absent in the single case with JS. In none of the subjects including controls was 3-D FT able to depict the SCP decussation. When seeded, the red dot resulted in the ventral tegmental decussation (VTD). It was normal in controls and in patients with COMA but was absent in our single patient with JSRD. MTS was identified in alla patients with COMA and in the patient with JSRD. Conclusion: MTS can be present in both COMA and JSRD but the underlying anatomy depicted by fibre tracking is distinct. The main difference is the integrity of the VTD in COM

The symmetry of the superconducting order parameter in PuCoGa5_5

The symmetry of the superconducting order parameter in single-crystalline PuCoGa$_5$ ($T_{\rm c} = 18.5$ K) is investigated via zero- and transverse- field muon spin relaxation ($\mu$SR) measurements, probing the possible existence of orbital and/or spin moments (time reversal-symmetry violation TRV) associated with the superconducting phase and the in-plane magnetic-field penetration depth $\lambda(T)$ in the mixed state, respectively. We find no evidence for TRV, and show that the superfluid density, or alternatively, $\Delta\lambda(T) = \lambda(T) - \lambda(0)$, are $\propto T$ for $T/T_{\rm c} \leq 0.5$. Taken together these measurements are consistent with an even-parity (pseudo-spin singlet), d-wave pairing state.Comment: 4 pages, 5 figure

Muon spin rotation measurements of the superfluid density in fresh and aged superconducting PuCoGa5_5

We have measured the temperature dependence and magnitude of the superfluid density $\rho_{\rm s}(T)$ via the magnetic field penetration depth $\lambda(T)$ in PuCoGa$_5$ (nominal critical temperature $T_{c0} = 18.5$ K) using the muon spin rotation technique in order to investigate the symmetry of the order parameter, and to study the effects of aging on the superconducting properties of a radioactive material. The same single crystals were measured after 25 days ($T_c = 18.25$ K) and 400 days ($T_c = 15.0$ K) of aging at room temperature. The temperature dependence of the superfluid density is well described in both materials by a model using d-wave gap symmetry. The magnitude of the muon spin relaxation rate $\sigma$ in the aged sample, $\sigma\propto 1/\lambda^2\propto\rho_s/m^*$, where $m^*$ is the effective mass, is reduced by about 70% compared to fresh sample. This indicates that the scattering from self-irradiation induced defects is not in the limit of the conventional Abrikosov-Gor'kov pair-breaking theory, but rather in the limit of short coherence length (about 2 nm in PuCoGa$_5$) superconductivity.Comment: 11 page

Hip fracture risk assessment: Artificial neural network outperforms conditional logistic regression in an age- and sex-matched case control study

Copyright @ 2013 Tseng et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background - Osteoporotic hip fractures with a significant morbidity and excess mortality among the elderly have imposed huge health and economic burdens on societies worldwide. In this age- and sex-matched case control study, we examined the risk factors of hip fractures and assessed the fracture risk by conditional logistic regression (CLR) and ensemble artificial neural network (ANN). The performances of these two classifiers were compared. Methods - The study population consisted of 217 pairs (149 women and 68 men) of fractures and controls with an age older than 60 years. All the participants were interviewed with the same standardized questionnaire including questions on 66 risk factors in 12 categories. Univariate CLR analysis was initially conducted to examine the unadjusted odds ratio of all potential risk factors. The significant risk factors were then tested by multivariate analyses. For fracture risk assessment, the participants were randomly divided into modeling and testing datasets for 10-fold cross validation analyses. The predicting models built by CLR and ANN in modeling datasets were applied to testing datasets for generalization study. The performances, including discrimination and calibration, were compared with non-parametric Wilcoxon tests. Results - In univariate CLR analyses, 16 variables achieved significant level, and six of them remained significant in multivariate analyses, including low T score, low BMI, low MMSE score, milk intake, walking difficulty, and significant fall at home. For discrimination, ANN outperformed CLR in both 16- and 6-variable analyses in modeling and testing datasets (p?<?0.005). For calibration, ANN outperformed CLR only in 16-variable analyses in modeling and testing datasets (p?=?0.013 and 0.047, respectively). Conclusions - The risk factors of hip fracture are more personal than environmental. With adequate model construction, ANN may outperform CLR in both discrimination and calibration. ANN seems to have not been developed to its full potential and efforts should be made to improve its performance.National Health Research Institutes in Taiwa

Performance characteristics of transrectal shear wave elastography (SWE) imaging in the evaluation of clinically localised prostate cancer:a prospective study

Objective: To test the diagnostic accuracy of SWE for the detection and phenotypic characterisation of PCa compared with whole-mount radical prostatectomy histopathology.Materials and Methods: This was a prospective protocol-driven diagnostic accuracy study. 212 consecutive men undergoing laparoscopic radical prostatectomy (LRP) for clinically localised PCa were recruited into the study. Quantitative stiffness data of the prostate gland was obtained in each patient using an endocavitary transrectal transducer before LRP and compared with detailed histopathological examination of radical prostatectomy specimen using 3-D printing mold based technology ensuring improved image-histology orientation. Receiver operator characteristic curves (ROC) were assessed between the groups.Results and limitations: Quantitative stiffness data estimated in kilopascals (kPa) was significantly higher in malignant compared with benign areas. With a cut-off value of 82.6 kPa, sensitivity and specificity of SWE were 96.8% and 67.8%, respectively (p&lt;0.05). Significant differences were observed for different grades of cancer with Young’s moduli 91.6kPa, 102.3kPa and 131.8kPa for low (Gleason score 6), intermediate (Gleason score 7) and high grade (Gleason score ≥ 8) PCa respectively (p&lt;0.05). SWE also detected capsular breaches with significant prediction of PCa pathologic staging. Potential limitations include selection bias and study being single centre site.Conclusions: Quantitative SWE via transrectal approach accurately detected cancer foci and showed significant differences between cancerous and benign tissue. Moreover, this technique can be used to reliably phenotype PCa aggressiveness

Prediction of postprostatectomy biochemical recurrence using quantitative ultrasound shear wave elastography imaging

Objectives: To determine the prognostic significance of tissue stiffness measurement using transrectal ultrasound shear wave elastography in predicting biochemical recurrence following radical prostatectomy for clinically localized prostate cancer.Patients and Methods: eligible male patients with clinically localized prostate cancer and extraperitoneal laparoscopic radical prostatectomy between November 2013 and August 2017 were retrospectively selected. Information of potential biochemical recurrence predictors, including imaging (ultrasound shear wave elastography and Magnetic Resonance Imaging), clinicopathological characteristics, and pre-operative PSA levels were obtained. Recurrence-free survival (Kaplan-Meier curve) and a multivariate model were constructed using Cox regression analysis to evaluate the impact of shear wave elastography as a prognostic marker for biochemical recurrence.Results: patients experienced biochemical recurrence in an average of 26.3±16.3 months during their follow-up. A cut-off of 144.85 kPa for tissue stiffness measurement was estimated for recurrence status at follow-up with sensitivity of 74.4% and specificity of 61.7%, respectively (p&lt;0.05). In univariate analysis, shear wave elastography performed well in all preoperative factors compared to biopsy Gleason Score, PSA and Magnetic Resonance Imaging; in multivariate analysis with postoperative pathological factors, shear wave elastography was statistically significant in predicting postoperative biochemical recurrence, which improved the C-index of predictive nomogram significantly (0.74 vs. 0.70, p&lt;0.05).Conclusions: The study revealed that quantitative ultrasound shear wave elastography measured tissue stiffness was a significant imaging marker that enhanced the predictive ability with other clinical and histopathological factors in prognosticating postoperative biochemical recurrence following radical prostatectomy for clinically localized prostate cancer