417 research outputs found
Evidence of distributed subpial T2* signal changes at 7T in multiple sclerosis : an histogram based approach
Subpial lesions are the most frequent type of cortical lesion in multiple sclerosis (MS), and are thought to be closely associated with poor clinical outcome. Neuropathological studies report that subpial lesions may come in two major types: they may appear as circumscribed, focal lesions, or extend across multiple adjacent gyri leading to a phenomenon termed âgeneral subpial demyelinationâ [1]. The in vivo evaluation of diffuse subpial disease is challenging â signal changes may be subtle, and extend across large regions where signal inhomogeneities due to B1 and RF receive coil non-uniformities become more pronounced. Here, we investigate whether a histogram-based analysis of T2* signal intensity in the cortex, at 7T MRI, can show evidence of distributed subpial cortical changes in patients with MS, as described histopathologically. We hypothesized that this phenomenon would be associated with significantly increased T2* signal intensity in patients compared to age-matched controls.Center Algoritm
Staging of endometrial cancer with MRI: Guidelines of the European Society of Urogenital Imaging
The purpose of this study was to define guidelines for endometrial cancer staging with MRI. The technique included critical review and expert consensus of MRI protocols by the female imaging subcommittee of the European Society of Urogenital Radiology, from ten European institutions, and published literature between 1999 and 2008. The results indicated that high field MRI should include at least two T2-weighted sequences in sagittal, axial oblique or coronal oblique orientation (short and long axis of the uterine body) of the pelvic content. High-resolution post-contrast images acquired at 2min ± 30 s after intravenous contrast injection are suggested to be optimal for the diagnosis of myometrial invasion. If cervical invasion is suspected, additional slice orientation perpendicular to the axis of the endocervical channel is recommended. Due to the limited sensitivity of MRI to detect lymph node metastasis without lymph node-specific contrast agents, retroperitoneal lymph node screening with pre-contrast sequences up to the level of the kidneys is optional. The likelihood of lymph node invasion and the need for staging lymphadenectomy are also indicated by high-grade histology at endometrial tissue sampling and by deep myometrial or cervical invasion detected by MRI. In conclusion, expert consensus and literature review lead to an optimized MRI protocol to stage endometrial cance
Staging of endometrial cancer with MRI: guidelines of the european society of urogenital imaging
The purpose of this study
was to define guidelines for endometrial
cancer staging with MRI. The
technique included critical review and
expert consensus of MRI protocols by the female imaging subcommittee of
the European Society of Urogenital
Radiology, from ten European institutions,
and published literature between
1999 and 2008. The results
indicated that high field MRI should
include at least two T2-weighted
sequences in sagittal, axial oblique or
coronal oblique orientation (short and
long axis of the uterine body) of the
pelvic content. High-resolution postcontrast
images acquired at 2 min ± 30 s
after intravenous contrast injection
are suggested to be optimal for the
diagnosis of myometrial invasion. If
cervical invasion is suspected, additional
slice orientation perpendicular
to the axis of the endocervical channel
is recommended. Due to the limited
sensitivity of MRI to detect lymph
node metastasis without lymph nodespecific
contrast agents, retroperitoneal
lymph node screening with
pre-contrast sequences up to the level
of the kidneys is optional. The likelihood
of lymph node invasion and
the need for staging lymphadenectomy
are also indicated by high-grade histology
at endometrial tissue sampling
and by deep myometrial or cervical
invasion detected by MRI. In conclusion,
expert consensus and literature
review lead to an optimized MRI
protocol to stage endometrial cancer
The Composition Gradient in M101 Revisited. II. Electron Temperatures and Implications for the Nebular Abundance Scale
(Abridged) We use high S/N spectra of 20 HII regions in the giant spiral
galaxy M101 to derive electron temperatures for the HII regions and robust
metal abundances over radii R = 0.19-1.25 Ro (6-41 kpc). We compare the
consistency of electron temperatures measured from the [O III]4363, [N II]5755,
[S III]6312, and [O II]7325 auroral lines. Temperatures from [O III], [S III],
and [N II] are correlated with relative offsets that are consistent with
expectations from nebular photoionization models. However, the temperatures
derived from the [O II]7325 line show a large scatter and are nearly
uncorrelated with temperatures derived from other ions. Our derived oxygen
abundances O/H are well fitted by an exponential distribution over six disk
scale lengths, from approximately 1.3 solar in the center to 1/15 solar in the
outermost region studied (for solar 12 + log (O/H)=8.7). We measure significant
radial gradients in N/O and He/H abundance ratios, but relatively constant S/O
and Ar/O. Our abundances are systematically lower by 0.2-0.5 dex than those
derived from the most widely used strong-line "empirical" abundance indicators.
We suspect that most of the disagreement with the strong-line abundances arises
from uncertainties in the nebular models that are used to calibrate the
"empirical" scale, and that strong-line abundances derived for HII regions and
emission-line galaxies are as much as a factor of two higher than the actual
oxygen abundances. However other explanations, such as the effects of
temperature fluctuations on the auroral line based abundances cannot be
completely ruled out. These results point to the need for direct abundance
determinations of a larger sample of extragalactic HII regions, especially for
objects more metal-rich than solar.Comment: 50 pages, 14 figures, 8 tables. Accepted by Ap
Staging of uterine cervical cancer with MRI: guidelines of the european society of urogenital radiology
Objective: To design clear guidelines for the
staging and follow-up of patients with uterine cervical
cancer, and to provide the radiologist with a framework for
use in multidisciplinary conferences. Methods: Guidelines
for uterine cervical cancer staging and follow-up were
defined by the female imaging subcommittee of the ESUR
(European Society of Urogenital Radiology) based on the
expert consensus of imaging protocols of 11 leading
institutions and a critical review of the literature. Results:
The results indicated that high field Magnetic Resonance
Imaging (MRI) should include at least two T2-weighted
sequences in sagittal, axial oblique or coronal obliqu
Setdb1-mediated H3K9 methylation is enriched on the inactive X and plays a role in its epigenetic silencing
Background: The presence of histone 3 lysine 9 (H3K9) methylation on the mouse inactive X chromosome has been controversial over the last 15 years, and the functional role of H3K9 methylation in X chromosome inactivation in any species has remained largely unexplored. Results: Here we report the first genomic analysis of H3K9 di- and tri-methylation on the inactive X: we find they are enriched at the intergenic, gene poor regions of the inactive X, interspersed between H3K27 tri-methylation domains found in the gene dense regions. Although H3K9 methylation is predominantly non-genic, we find that depletion of H3K9 methylation via depletion of H3K9 methyltransferase Set domain bifurcated 1 (Setdb1) during the establishment of X inactivation, results in failure of silencing for around 150 genes on the inactive X. By contrast, we find a very minor role for Setdb1-mediated H3K9 methylation once X inactivation is fully established. In addition to failed gene silencing, we observed a specific failure to silence X-linked long-terminal repeat class repetitive elements. Conclusions: Here we have shown that H3K9 methylation clearly marks the murine inactive X chromosome. The role of this mark is most apparent during the establishment phase of gene silencing, with a more muted effect on maintenance of the silent state. Based on our data, we hypothesise that Setdb1-mediated H3K9 methylation plays a role in epigenetic silencing of the inactive X via silencing of the repeats, which itself facilitates gene silencing through alterations to the conformation of the whole inactive X chromosome.Andrew Keniry, Linden J. Gearing, Natasha Jansz, Joy Liu, Aliaksei Z. Holik, Peter F. Hickey, Sarah A. Kinkel, Darcy L. Moore, Kelsey Breslin, Kelan Chen, Ruijie Liu, Catherine Phillips, Miha Pakusch, Christine Biben, Julie M. Sheridan, Benjamin T. Kile, Catherine Carmichael, Matthew E. Ritchie, Douglas J. Hilton and Marnie E. Blewit
Microbiology of the phyllosphere: a playground for testing ecological concepts
Many concepts and theories in ecology are highly debated, because it is often difficult to design decisive tests with sufficient replicates. Examples include biodiversity theories, succession concepts, invasion theories, coexistence theories, and concepts of life history strategies. Microbiological tests of ecological concepts are rapidly accumulating, but have yet to tap into their full potential to complement traditional macroecological theories. Taking the example of microbial communities on leaf surfaces (i.e. the phyllosphere), we show that most explorations of ecological concepts in this field of microbiology focus on autecology and population ecology, while community ecology remains understudied. Notable exceptions are first tests of the island biogeography theory and of biodiversity theories. Here, the phyllosphere provides the unique opportunity to set up replicated experiments, potentially moving fields such as biogeography, macroecology, and landscape ecology beyond theoretical and observational evidence. Future approaches should take advantage of the great range of spatial scales offered by the leaf surface by iteratively linking laboratory experiments with spatial simulation models
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