63,068 research outputs found
INTEGRAL and Nuclear Astrophysics
We briefly review the fundamentals of nuclear gamma-ray line astronomy
(radioactive astronomy), focusing on its role to decipher the intimate physics
of supernovae, either immediatly (via or after a time delay (via
). All kinds of supernovae can be in principle tested through their
radioactivities and their associated gamma-ray lines.
Dedicated to the spectroscopy and imaging of celestial sources in the 15 keV
to 10 MeV band, the ESA scientific observatory INTEGRAL will open a golden age
of nuclear astrophysics in EuropeComment: Invited review, "Cosmic Evolution", meeting in honor of the 60th
birthday of Jean Audouze and Jim Truran, to be published by World Scientific,
6 pages, 1 figur
On the origin of Goa Cathedral former altarpiece: Material and technical assessment to the work of Garcia Fernandes, Portuguese painter from 16th century Lisbon workshop
Goa Cathedral former altarpiece is one of the oldest set of paintings in India. The seven remaining paintings from the first altarpiece of Goa Cathedral, nowadays in the sacristy, are attributed by some art historians to Master Garcia Fernandes (act. 1514â1565), Portuguese painter from Lisbon workshop. The 16th century was the âGolden ageâ of Portuguese painting. In this context the Royal Lisbon workshop played a predominant role, where the activity of the painter Garcia Fernandes and his workshop can be distinguished. In this new approach, Goa paintings are being studied and compared with other works in Portuguese territory attributed to this same painter, as St. Bartholomew altarpiece from the chapel of Bartolomeu Joanes in Lisbon Cathedral.
The stratigraphic study allowed to compare ground layers, pigments and binders which, were characterized using complementary analytical and imaging techniques: (X-ray Fluorescence spectrometry (XRF), Infrared Reflectography (IRR), Infrared Photography (IRP), Macro Photography (MP), micro-X-ray Diffraction (Ό-XRD), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), Raman micro-spectroscopy (Ό-Raman), Fourier Transform Infrared micro-spectroscopy (Ό-FTIR), Pyrolysis gas chromatography mass spectrometry (PY-GC/MS). This work brought a new insight on the techniques and materials used in this Masterpiece and highlighted the conclusion that Goa Cathedral former altarpiece must be a Portuguese production
High-resolution DCE-MRI of the pituitary gland using radial k-space acquisition with compressed sensing reconstruction
BACKGROUND AND PURPOSE: The pituitary gland is located outside of the blood-brain barrier. Dynamic T1 weighted contrast enhanced sequence is considered to be the gold standard to evaluate this region. However, it does not allow assessment of intrinsic permeability properties of the gland. Our aim was to demonstrate the utility of radial volumetric interpolated brain examination with the golden-angle radial sparse parallel technique to evaluate permeability characteristics of the individual components (anterior and posterior gland and the median eminence) of the pituitary gland and areas of differential enhancement and to optimize the study acquisition time.
MATERIALS AND METHODS: A retrospective study was performed in 52 patients (group 1, 25 patients with normal pituitary glands; and group 2, 27 patients with a known diagnosis of microadenoma). Radial volumetric interpolated brain examination sequences with goldenangle radial sparse parallel technique were evaluated with an ROI-based method to obtain signal-time curves and permeability measures of individual normal structures within the pituitary gland and areas of differential enhancement. Statistical analyses were performed to assess differences in the permeability parameters of these individual regions and optimize the study acquisition time.
RESULTS: Signal-time curves from the posterior pituitary gland and median eminence demonstrated a faster wash-in and time of
maximum enhancement with a lower peak of enhancement compared with the anterior pituitary gland (P .005). Time-optimization
analysis demonstrated that 120 seconds is ideal for dynamic pituitary gland evaluation. In the absence of a clinical history, differences in the signal-time curves allow easy distinction between a simple cyst and a microadenoma.
CONCLUSIONS: This retrospective study confirms the ability of the golden-angle radial sparse parallel technique to evaluate the
permeability characteristics of the pituitary gland and establishes 120 seconds as the ideal acquisition time for dynamic pituitary gland
imaging
Real-time Assessment of Right and Left Ventricular Volumes and Function in Children Using High Spatiotemporal Resolution Spiral bSSFP with Compressed Sensing
Background: Real-time (RT) assessment of ventricular volumes and function
enables data acquisition during free-breathing. However, in children the
requirement for high spatiotemporal resolution requires accelerated imaging
techniques. In this study, we implemented a novel RT bSSFP spiral sequence
reconstructed using Compressed Sensing (CS) and validated it against the
breath-hold (BH) reference standard for assessment of ventricular volumes in
children with heart disease.
Methods: Data was acquired in 60 children. Qualitative image scoring and
evaluation of ventricular volumes was performed by 3 clinical cardiac MR
specialists. 30 cases were reassessed for intra-observer variability, and the
other 30 cases for inter-observer variability.
Results: Spiral RT images were of good quality, however qualitative scores
reflected more residual artefact than standard BH images and slightly lower
edge definition. Quantification of Left Ventricular (LV) and Right Ventricular
(RV) metrics showed excellent correlation between the techniques with narrow
limits of agreement. However, we observed small but statistically significant
overestimation of LV end-diastolic volume, underestimation of LV end-systolic
volume, as well as a small overestimation of RV stroke volume and ejection
fraction using the RT imaging technique. No difference in inter-observer or
intra-observer variability were observed between the BH and RT sequences.
Conclusions: Real-time bSSFP imaging using spiral trajectories combined with
a compressed sensing reconstruction is feasible. The main benefit is that it
can be acquired during free breathing. However, another important secondary
benefit is that a whole ventricular stack can be acquired in ~20 seconds, as
opposed to ~6 minutes for standard BH imaging. Thus, this technique holds the
potential to significantly shorten MR scan times in children
The Evidence Behind the Treatment of Canine Idiopathic Epilepsy
Oral phenobarbital and imepitoin in particular, followed by potassium bromide and levetiracetam are likely to be effective for the treatment of canine idiopathic epilepsy. There is strong evidence supporting the use of oral phenobarbital and imepitoin as âfirst lineâ medications. However, there remains a lack of evidence for targeted treatment for the various individual epileptic phenotypes and quite limited evidence on direct comparisons of the efficacy between various anti-epileptic drugs
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Clinicopathological characteristics of histiocytic sarcoma affecting the central nervous system in dogs.
BackgroundHistiocytic sarcoma affecting the central nervous system (CNS HS) in dogs may present as primary or disseminated disease, often characterized by inflammation. Prognosis is poor, and imaging differentiation from other CNS tumors can be problematic.ObjectiveTo characterize the clinicopathological inflammatory features, breed predisposition, and survival in dogs with CNS HS.AnimalsOne hundred two dogs with HS, 62 dogs with meningioma.MethodsRetrospective case series. Records were reviewed for results of cerebrospinal fluid (CSF) analysis, CBC, treatment, and outcome data.ResultsPredisposition for CNS HS was seen in Bernese Mountain Dogs, Golden Retrievers, Rottweilers, Corgis, and Shetland Sheepdogs (Pââ€â.001). Corgis and Shetland Sheepdogs had predominantly primary tumors; Rottweilers had exclusively disseminated tumors. Marked CSF inflammation was characteristic of primary rather than disseminated HS, and neoplastic cells were detected in CSF of 52% of affected dogs. Increased neutrophil to lymphocyte ratios were seen in all groups relative to controls (Pâ<.008) but not among tumor subtypes. Definitive versus palliative treatment resulted in improved survival times (Pâ<â.001), but overall prognosis was poor.Conclusions and clinical importanceClinicopathological differences between primary and disseminated HS suggest that tumor biological behavior and origin may be different. Corgis and Shetland Sheepdogs are predisposed to primary CNS HS, characterized by inflammatory CSF. High total nucleated cell count and the presence of neoplastic cells support the use of CSF analysis as a valuable diagnostic test. Prognosis for CNS HS is poor, but further evaluation of inflammatory mechanisms may provide novel therapeutic opportunities
Treatment of intrahepatic congenital portosystemic shunts in dogs: a systematic review
The aim of this study was to establish the evidence base for the treatment of intrahepatic congenital portosystemic shunts in dogs through a systematic review of the pertinent literature. Studies were filtered for evidence to answer the question âWhich of the treatment options for intrahepatic CPSS in dogs offers the best shortâ and longâterm outcome?â Studies were assigned a level of evidence based on a system published by the Oxford Centre for EvidenceâBased Medicine. Thirtyâtwo studies were included in the review. Twentyâsix provided level 4 evidence and six provided level 5 evidence. There were no level 1, 2 or 3 studies. One study compared surgical treatment with medical management and one study compared suture ligation with ameroid constrictor placement. The remaining studies were case series describing the outcome for one treatment method alone. Methods and timings of assessments of shortâ and longâterm outcomes were highly varied, making direct comparisons challenging. The evidence regarding the treatment of intrahepatic congenital portosystemic shunts in dogs is weak, with only two studies directly comparing treatments. There is a lack of evidence regarding shortâ and longâterm outcomes on which to base clinical decisions
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