107 research outputs found
Myocardial Infarction Quantification From Late Gadolinium Enhancement MRI Using Top-hat Transforms and Neural Networks
Significance: Late gadolinium enhanced magnetic resonance imaging (LGE-MRI)
is the gold standard technique for myocardial viability assessment. Although
the technique accurately reflects the damaged tissue, there is no clinical
standard for quantifying myocardial infarction (MI), demanding most algorithms
to be expert dependent. Objectives and Methods: In this work a new automatic
method for MI quantification from LGE-MRI is proposed. Our novel segmentation
approach is devised for accurately detecting not only hyper-enhanced lesions,
but also microvascular-obstructed areas. Moreover, it includes a myocardial
disease detection step which extends the algorithm for working under healthy
scans. The method is based on a cascade approach where firstly, diseased slices
are identified by a convolutional neural network (CNN). Secondly, by means of
morphological operations a fast coarse scar segmentation is obtained. Thirdly,
the segmentation is refined by a boundary-voxel reclassification strategy using
an ensemble of CNNs. For its validation, reproducibility and further comparison
against other methods, we tested the method on a big multi-field expert
annotated LGE-MRI database including healthy and diseased cases. Results and
Conclusion: In an exhaustive comparison against nine reference algorithms, the
proposal achieved state-of-the-art segmentation performances and showed to be
the only method agreeing in volumetric scar quantification with the expert
delineations. Moreover, the method was able to reproduce the intra- and
inter-observer variability ranges. It is concluded that the method could
suitably be transferred to clinical scenarios.Comment: Submitted to IEE
The MUSE Hubble Ultra Deep Field Survey X. Ly Equivalent Widths at
We present rest-frame Ly equivalent widths (EW) of 417 Ly
emitters (LAEs) detected with Multi Unit Spectroscopic Explorer (MUSE) on the
Very Large Telescope (VLT) at in the Hubble Ultra Deep Field.
Based on the deep MUSE spectroscopy and ancillary Hubble Space Telescope (HST)
photometry data, we carefully measured EW values taking into account extended
Ly emission and UV continuum slopes (). Our LAEs reach
unprecedented depths, both in Ly luminosities and UV absolute
magnitudes, from log(/erg s) 41.0 to 43.0 and
from Muv -16 to -21 (0.01-1.0 ). The EW values span the
range of 5 to 240 \AA\ or larger, and their distribution can be well
fitted by an exponential law exp(EW/). Owing to
the high dynamic range in Muv, we find that the scale factor, ,
depends on Muv in the sense that including fainter Muv objects increases
, i.e., the Ando effect. The results indicate that selection
functions affect the EW scale factor. Taking these effects into account, we
find that our values are consistent with those in the literature
within uncertainties at at a given threshold of Muv
and . Interestingly, we find 12 objects with EW \AA\
above uncertainties. Two of these 12 LAEs show signatures of merger
or AGN activity: the weak CIV emission line. For the remaining
10 very large EW LAEs, we find that the EW values can be reproduced by young
stellar ages ( Myr) and low metallicities ( ). Otherwise, at least part of the Ly emission in these LAEs
needs to arise from anisotropic radiative transfer effects, fluorescence by
hidden AGN or quasi-stellar object activity, or gravitational cooling.Comment: 22 pages, 12 figures, 9 tables, accepted for publication in A&A (MUSE
UDF Series Paper X
Système rénine-angiotensine et cancers urologiques / Renin-angiotensin system and urological cancers.
International audienceIntroduction: A controversy animates the literature on the potential role of the rennin-angiotensin system (RAS) in tumorogenesis. The objective of this review was to determine the involvement of this pathway in cancer, and more specifically in urological cancers. Material and Method: We made a systematic review of articles referenced in Pubmed, using the following keywords alone or combined: cancer, renin, angiotensin, VEGF, AT1R, antagonists of angiotensin-2 receptors, inhibitors of angiotensinogen converting. Results: Many types of cancers overexpress AT1-R in their tumoral tissues (breast, stomach, bladder, astrocytoma, glioblastoma, ovary, uterus, pancreas, kidney, prostate, adrenal gland). Ang-II can induce VEGF-A expression and promote neoangiogenesis, but also can trigger different molecular pathways involved in cell proliferation or inhibit apoptosis. Several xenograft murin models demonstrated anti-tumoral efficacy of RAS blockers, alone or using combined therapies, targeting angiogenesis and slowing down tumor growth. Retrospective studies in patients have also revealed a better progression-free survival and a better response to therapies in those treated with RAS blockers. Conclusion: Many data seem to demonstrate the involvement of the RAS in carcinogenesis, as well as anti-tumoral effect of RAS blockers in addition to anti-cancer treatments. Clinical data are now expected to confirm these experimental findings
A review of multisite pacing to achieve cardiac resynchronization therapy
Non-response to cardiac resynchronization therapy remains a significant problem in up to 30% of patients. Multisite stimulation has emerged as a way of potentially overcoming non-response. This may be achieved by the use of multiple leads placed within the coronary sinus and its tributaries (dual-vein pacing) or more recently by the use of multipolar (quadripolar) left ventricular pacing leads which can deliver pacing stimuli at multiple sites within the same vein. This review covers the role of multisite pacing including the interaction with the underlying pathophysiology, the current and planned studies, and the potential pitfalls of this technolog
Median Surface Brightness Profiles of Lyman- Haloes in the MUSE Extremely Deep Field
We present the median surface brightness profiles of diffuse Ly
haloes (LAHs) around star-forming galaxies by stacking 155 spectroscopically
confirmed Ly emitters (LAEs) at 3<z<4 in the MUSE Extremely Deep Field
(MXDF), with median Ly luminosity . After correcting for a systematic surface brightness
offset we identified in the datacube, we detect extended Ly emission
out to a distance of 270 kpc. The median Ly surface brightness profile
shows a power-law decrease in the inner 20 kpc, and a possible flattening trend
at larger distance. This shape is similar for LAEs with different Ly
luminosities, but the normalisation of the surface brightness profile increases
with luminosity. At distances larger than 50 kpc, we observe strong overlap of
adjacent LAHs, and the Ly surface brightness is dominated by the LAHs
of nearby LAEs. We find no clear evidence of redshift evolution of the observed
Ly profiles when comparing with samples at 4<z<5 and 5<z<6. Our results
are consistent with a scenario in which the inner 20 kpc of the LAH is powered
by star formation in the central galaxy, while the LAH beyond a radius of 50
kpc is dominated by photons from surrounding galaxies.Comment: Submitted to A&
On the evolution of the size of Lyman alpha halos across cosmic time: no change in the circumgalactic gas distribution when probed by line emission
Lyman (Ly) is now routinely used as a tool for studying
high-redshift galaxies and its resonant nature means it can trace neutral
hydrogen around star-forming galaxies. Integral field spectrograph measurements
of high-redshift Ly emitters indicate that significant extended
Ly halo emission is ubiquitous around such objects. We present a sample
of redshift 0.23 to 0.31 galaxies observed with the Hubble Space Telescope
selected to match the star formation properties of high- samples while
optimizing the observations for detection of low surface brightness Ly
emission. The Ly escape fractions range between 0.7\% and 37\%, and we
detect extended Ly emission around six out of seven targets. We find
Ly halo to UV scale length ratios around 6:1 which is marginally lower
than high-redshift observations, and halo flux fractions between 60\% and 85\%
-- consistent with high-redshift observations -- when using comparable methods.
However, our targets show additional extended stellar UV emission: we
parametrize this with a new double exponential model. We find that this
parametrization does not strongly affect the observed Ly halo
fractions. We find that deeper H data would be required to firmly
determine the origin of Ly halo emission, however, there are
indications that H is more extended than the central FUV profile,
potentially indicating conditions favorable for the escape of ionizing
radiation. We discuss our results in the context of high-redshift galaxies,
cosmological simulations, evolutionary studies of the circumgalactic medium in
emission, and the emission of ionizing radiation.Comment: 20 page, 14 figures, 6 tables. Accepted for publication in MNRA
Recommended from our members
The MUSE Extremely Deep Field: The cosmic web in emission at high redshift
We report the discovery of diffuse extended Lyα emission from redshift 3.1 to 4.5, tracing cosmic web filaments on scales of 2.5-4 cMpc. These structures have been observed in overdensities of Lyα emitters in the MUSE Extremely Deep Field, a 140 h deep MUSE observation located in the Hubble Ultra-Deep Field. Among the 22 overdense regions identified, five are likely to harbor very extended Lyα emission at high significance with an average surface brightness of 5 × 10-20 erg s-1 cm-2 arcsec-2. Remarkably, 70% of the total Lyα luminosity from these filaments comes from beyond the circumgalactic medium of any identified Lyα emitter. Fluorescent Lyα emission powered by the cosmic UV background can only account for less than 34% of this emission at z ≈ 3 and for not more than 10% at higher redshift. We find that the bulk of this diffuse emission can be reproduced by the unresolved Lyα emission of a large population of ultra low-luminosity Lyα emitters (< 1040 erg s-1), provided that the faint end of the Lyα luminosity function is steep (α ⪅ -1.8), it extends down to luminosities lower than 1038 - 1037 erg s-1, and the clustering of these Lyα emitters is significant (filling factor < 1/6). If these Lyα emitters are powered by star formation, then this implies their luminosity function needs to extend down to star formation rates < 10-4M yr-1. These observations provide the first detection of the cosmic web in Lyα emission in typical filamentary environments and the first observational clue indicating the existence of a large population of ultra low-luminosity Lyα emitters at high redshift. © R. Bacon et al. 2021
In Heart Failure Patients with Left Bundle Branch Block Single Lead MultiSpot Left Ventricular Pacing Does Not Improve Acute Hemodynamic Response To Conventional Biventricular Pacing. A Multicenter Prospective, Interventional, Non-Randomized Study.
Introduction Recent efforts to increase CRT response by multiSPOT pacing (MSP) from multiple bipols on the same left ventricular lead are still inconclusive. Aim The Left Ventricular (LV) MultiSPOTpacing for CRT (iSPOT) study compared the acute hemodynamic response of MSP pacing by using 3 electrodes on a quadripolar lead compared with conventional biventricular pacing (BiV). Methods Patients with left bundle branch block (LBBB) underwent an acute hemodynamic study to determine the %change in LV+dP/dtmax from baseline atrial pacing compared to the following configurations: BiV pacing with the LV lead in a one of lateral veins, while pacing from the distal, mid, or proximal electrode and all 3 electrodes together (i.e. MSP). All measurements were repeated 4 times at 5 different atrioventricular delays. We also measured QRS-width and individual Q-LV durations. Results Protocol was completed in 24 patients, all with LBBB (QRS width 171±20 ms) and 58% ischemic aetiology. The percentage change in LV+dP/dtmax for MSP pacing was 31.0±3.3% (Mean±SE), which was not significantly superior to any BiV pacing configuration: 28.9±3.2% (LV-distal), 28.3±2.7% (LV-mid), and 29.5±3.0% (LV-prox), respectively. Correlation between LV+dP/dtmax and either QRS-width or Q-LV ratio was poor. Conclusions In patients with LBBB MultiSPOT LV pacing demonstrated comparable improvement in contractility to best conventional BiV pacing. Optimization of atrioventricular delay is important for the best performance for both BiV and MultiSPOT pacing configurations. Trial Registration ClinicalTrials.gov NTC0188314
Large expert-curated database for benchmarking document similarity detection in biomedical literature search
Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe
Association entre le score syntax post-revascularisation et l'ischémie myocardique à 6 mois d'un infarctus du myocarde
Introduction : Le score SYNTAX (SS) caractérise la complexité du réseau coronaire. De nombreuses études ont démontré le rôle pronostic du SS et du score SYNTAX résiduel (SSr) après un syndrome coronarien aigu [1]. Objectifs : L association entre le SSr et l ischémie résiduelle évaluée par scintigraphie myocardique de perfusion (gSPECT) dans les 6 mois après un infarctus du myocarde (IDM) expliquerait le pronostic défavorable de ces patients. Matériels et méthodes : 245 patients, hospitalisés pour un SCA entre janvier 2009 et décembre 2010 et ayant bénéficié d une coronarographie ont été inclus prospectivement. Le SS et le SSr ont été mesurés respectivement avant et après chaque coronarographie. Une scintigraphie myocardique de stress et de repos au 99mTc-sestamibi a été pratiquée dans les 6 mois. Résultats : Les patients ont été divisés en 2 groupes selon les tertiles de SSr : > 4 (81 patients), vs. SSr 4 (OR: 3.49, 95% CI: 1.06-11.51; p=0.04) et la FEVG post-stress 4 est associé avec l ischémie myocardique 6 mois après un IDM. Le SSr > 4 est également un facteur prédictif d ECM à 1 an avec l âge et la FEVG post-stress < 45%. L étude montre pour la première fois l association entre le SSr et l ischémie myocardique.DIJON-BU Médecine Pharmacie (212312103) / SudocSudocFranceF
- …