Objectives
To (1) develop a fully automated deep learning (DL) algorithm based on gadoxetic acid–enhanced hepatobiliary phase (HBP) MRI and (2) compare the diagnostic performance of DL vs. MR ...elastography (MRE) for noninvasive staging of liver fibrosis.
Methods
This single-center retrospective study included 355 patients (M/F 238/117, mean age 60 years; training,
n
= 178; validation,
n
= 123; test,
n
= 54) who underwent gadoxetic acid–enhanced abdominal MRI, including HBP and MRE, and pathological evaluation of the liver within 1 year of MRI. Cropped liver HBP images from a custom-written fully automated liver segmentation were used as input for DL. A transfer learning approach based on the ImageNet VGG16 model was used. Different DL models were built for the prediction of fibrosis stages F1-4, F2-4, F3-4, and F4. ROC analysis was performed to evaluate the performance of DL in training, validation, and test sets and of MRE liver stiffness in the test set.
Results
AUC values of DL were 0.99/0.70/0.77 (F1-4), 0.92/0.71/0.91 (F2-4), 0.91/0.78/0.90 (F3-4), and 0.98/0.83/0.85 (F4) for training/validation/test sets, respectively. The AUCs of MRE liver stiffness in the test set were 0.86 (F1-4), 0.87 (F2-4), 0.92 (F3-4), and 0.86 (F4). AUCs of MRE and DL were not significantly different for any of the fibrosis stages (
p
> 0.134).
Conclusions
The fully automated DL models based on HBP gadoxetic acid MRI showed good-to-excellent diagnostic performance for staging of liver fibrosis, with similar diagnostic performance to MRE. After validation in independent sets, the DL algorithm may allow for noninvasive liver fibrosis assessment without the need for additional MRI hardware.
Key Points
•
The developed deep learning algorithm, based on routine standard-of-care gadoxetic acid–enhanced MRI data, showed good-to-excellent diagnostic performance for noninvasive staging of liver fibrosis.
•
The diagnostic performance of the deep learning algorithm was equivalent to that of MR elastography in a separate test set.
Measurements of stellar properties of galaxies when the universe was less than one billion years old yield some of the only observational constraints on the onset of star formation. We present here ...the inclusion of Spitzer/IRAC imaging in the fitting of the spectral energy distribution of the seven highest-redshift galaxy candidates selected from the Hubble Space Telescope (HST) imaging of the Reionization Lensing Cluster Survey. We find that for six out of eight HST-selected z ∼ 8 sources, the z ∼ 8 solutions are still strongly preferred over z ∼ 1-2 solutions after the inclusion of Spitzer fluxes, and two prefer a z ∼ 7 solution, which we defer to a later analysis. We find a wide range of intrinsic stellar masses (5 × 106-4 × 109 M ), star formation rates (0.2-14 M yr−1), and ages (30-600 Myr) among our sample. Of particular interest is A1763-1434, which shows evidence of an evolved stellar population (∼500 Myr) at z ∼ 8, implying that its first generation of star formation occurred <100 Myr after the Big Bang. SPT0615-JD, a spatially resolved z ∼ 10 candidate, remains at its high redshift, supported by deep Spitzer/IRAC data, and also shows some evidence for an evolved stellar population. Even with the lensed, bright apparent magnitudes of these z 8 candidates (H = 26.1-27.8 AB mag), only the James Webb Space Telescope will be able to exclude the possibility of abnormally strong nebular emission, large dust content, or some combination thereof, and confirm the presence of evolved stellar populations early in the universe.
We derive relations between the effective radii Reff of galaxies and the virial radii R200c of their dark matter halos over the redshift range 0 < z < 3. For galaxies, we use the measured sizes from ...deep images taken with Hubble Space Telescope for the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey; for halos, we use the inferred sizes from abundance matching to cosmological dark matter simulations via a stellar mass-halo mass (SMHM) relation. For this purpose, we derive a new SMHM relation based on the same selection criteria and other assumptions as for our sample of galaxies with size measurements. As a check on the robustness of our results, we also derive Reff-R200c relations for three independent SMHM relations from the literature. We find that galaxy Reff is proportional on average to halo R200c, confirming and extending to high redshifts the z = 0 results of Kravtsov. Late-type galaxies (with low Sérsic index and high specific star formation rate (sSFR)) follow a linear Reff-R200c relation, with effective radii at 0.5 < z < 3 close to those predicted by simple models of disk formation; at z < 0.5, the sizes of late-type galaxies appear to be slightly below this prediction. Early-type galaxies (with high Sérsic index and low sSFR) follow a roughly parallel Reff-R200c relation, ∼0.2-0.3 dex below the one for late-type galaxies. Our observational results, reinforced by recent hydrodynamical simulations, indicate that galaxies grow quasi-homologously with their dark matter halos.
We combine deep Hubble Space Telescope grism spectroscopy with a new Bayesian method to derive maps of gas-phase metallicity for 10 star-forming galaxies at high redshift ( ). Exploiting lensing ...magnification by the foreground cluster MACS1149.6+2223, we reach sub-kiloparsec spatial resolution and push the limit of stellar mass associated with such high-z spatially resolved measurements below for the first time. Our maps exhibit diverse morphologies, indicative of various effects such as efficient radial mixing from tidal torques, rapid accretion of low-metallicity gas, and other physical processes that can affect the gas and metallicity distributions in individual galaxies. Based upon an exhaustive sample of all existing sub-kiloparesec resolution metallicity gradient measurements at high z, we find that predictions given by analytical chemical evolution models assuming a relatively extended star-formation profile in the early disk-formation phase can explain the majority of observed metallicity gradients, without involving galactic feedback or radial outflows. We observe a tentative correlation between stellar mass and metallicity gradients, consistent with the "downsizing" galaxy formation picture that more massive galaxies are more evolved into a later phase of disk growth, where they experience more coherent mass assembly at all radii and thus show shallower metallicity gradients. In addition to the spatially resolved analysis, we compile a sample of homogeneously cross-calibrated integrated metallicity measurements spanning three orders of magnitude in stellar mass at z ∼ 1.8. We use this sample to study the mass-metallicity relation (MZR) and find that the slope of the observed MZR can rule out the momentum-driven wind model at a 3 confidence level.
Abstract
Based on spectroscopy and multiband wide-field observations of the gravitationally lensed quasar HE 0435−1223, we determine the probability distribution function of the external convergence ...κext for this system. We measure the under/overdensity of the line of sight towards the lens system and compare it to the average line of sight throughout the Universe, determined by using the CFHTLenS (The Canada France Hawaii Lensing Survey) as a control field. Aiming to constrain κext as tightly as possible, we determine under/overdensities using various combinations of relevant informative weighting schemes for the galaxy counts, such as projected distance to the lens, redshift and stellar mass. We then convert the measured under/overdensities into a κext distribution, using ray-tracing through the Millennium Simulation. We explore several limiting magnitudes and apertures, and account for systematic and statistical uncertainties relevant to the quality of the observational data, which we further test through simulations. Our most robust estimate of κext has a median value $\kappa ^\mathrm{med}_\mathrm{ext} = 0.004$ and a standard deviation σκ = 0.025. The measured σκ corresponds to 2.5 per cent relative uncertainty on the time delay distance, and hence the Hubble constant H0 inferred from this system. The median $\kappa ^\mathrm{med}_\mathrm{ext}$ value varies by ∼0.005 with the adopted aperture radius, limiting magnitude and weighting scheme, as long as the latter incorporates galaxy number counts, the projected distance to the main lens and a prior on the external shear obtained from mass modelling. This corresponds to just ∼0.5 per cent systematic impact on H0. The availability of a well-constrained κext makes HE 0435−1223 a valuable system for measuring cosmological parameters using strong gravitational lens time delays.
We present the first results of the K-band Multi-Object Spectrometer (KMOS) Lens-Amplified Spectroscopic Survey, a new ESO Very Large Telescope large program, doing multi-object integral field ...spectroscopy of galaxies gravitationally lensed behind seven galaxy clusters selected from the Hubble Space Telescope (HST) Grism Lens-Amplified Survey from Space. Using the power of the cluster magnification, we are able to reveal the kinematic structure of 25 galaxies at , in four cluster fields, with stellar masses . This sample includes five sources at with lower stellar masses than in any previous kinematic integral field unit (IFU) surveys. Our sample displays a diversity in kinematic structure over this mass and redshift range. The majority of our kinematically resolved sample is rotationally supported, but with a lower ratio of rotational velocity to velocity dispersion than in the local universe, indicating the fraction of dynamically hot disks changes with cosmic time. We find that no galaxies with stellar mass in our sample display regular ordered rotation. Using the enhanced spatial resolution from lensing, we resolve a lower number of dispersion-dominated systems compared to field surveys, competitive with findings from surveys using adaptive optics. We find that the KMOS IFUs recover emission line flux from HST grism-selected objects more faithfully than slit spectrographs. With artificial slits, we estimate that slit spectrographs miss, on average, 60% of the total flux of emission lines, which decreases rapidly if the emission line is spatially offset from the continuum.
The most distant galaxies known are at z ∼ 10-11, observed 400-500 Myr after the Big Bang. The few z ∼ 10-11 candidates discovered to date have been exceptionally small, barely resolved, if at all, ...by the Hubble Space Telescope. Here we present the discovery of SPT0615-JD1, a fortuitous z ∼ 10 (zphot = ) galaxy candidate stretched into an arc over ∼2 5 by the effects of strong gravitational lensing. Discovered in the Reionization Lensing Cluster Survey (RELICS) Hubble Treasury program and companion S-RELICS Spitzer program, this candidate has a lensed H-band magnitude of 24.6 0.1 AB mag. With a magnification of ∼ 4-7 estimated from our lens models, the delensed intrinsic magnitude is 26.7 0.1 AB mag, and the half-light radius is re < 0.8 kpc, both consistent with other z > 9 candidates. The inferred stellar mass ( ) and star formation rate ( ) indicate that this candidate is a typical star-forming galaxy on the z > 6 SFR-M relation. We note that three independent lens models predict two counter images, at least one of which should be of a similar magnitude to the arc, but these counter images are not yet detected. Counter images would not be expected if the arc were at lower redshift. The relatively large physical size could be due to a merger or accretion event, while the unprecedented lensed size of this z ∼ 10 candidate offers the potential for ALMA and the James Webb Space Telescope to study the geometric and kinematic properties of a galaxy observed 500 Myr after the Big Bang.
We study the bivariate size-luminosity distribution of Lyman break galaxies (LBGs) selected at redshifts around 4 and 5 in GOODS and the HUDF fields. We model the size-luminosity distribution as a ...combination of log-normal distribution (in size) and Schechter function (in luminosity), therefore it enables a more detailed study of the selection effects. We perform extensive simulations to quantify the dropout-selection completenesses and measurement biases and uncertainties in two-dimensional size and magnitude bins, and transform the theoretical size-luminosity distribution to the expected distribution for the observed data. Using maximum-likelihood estimator, we find that the Schechter function parameters for B sub(435)-dropouts and are consistent with the values in the literature, but the size distributions are wider than expected from the angular momentum distribution of the underlying dark matter halos. The slope of the size-luminosity (RL) relation is similar to those found for local disk galaxies, but considerably shallower than local early-type galaxies.
Using deep Hubble Frontier Fields imaging and slitless spectroscopy from the Grism Survey from Space, we study 2200 cluster and 1748 field galaxies at to determine the impact of environment on galaxy ...size and structure at stellar masses , an unprecedented limit at these redshifts. Based on simple assumptions- -we find no significant differences in half-light radii (re) between equal-mass cluster or field systems. More complex analyses- -reveal local density ( ) to induce only a 7% 3% (95% confidence) reduction in re beyond what can be accounted for by U − V color, Sérsic index (n), and redshift (z) effects. Almost any size difference between galaxies in high- and low-density regions is thus attributable to their different distributions in properties other than environment. Indeed, we find a clear color-re correlation in low-mass passive cluster galaxies ( ) such that bluer systems have larger radii, with the bluest having sizes consistent with equal-mass star-forming galaxies. We take this as evidence that large-re low-mass passive cluster galaxies are recently acquired systems that have been environmentally quenched without significant structural transformation (e.g., by ram pressure stripping or starvation). Conversely, ∼20% of small-re low-mass passive cluster galaxies appear to have been in place since . Given the consistency of the small-re galaxies' stellar surface densities (and even colors) with those of systems more than ten times as massive, our findings suggest that clusters mark places where galaxy evolution is accelerated for an ancient base population spanning most masses, with late-time additions quenched by environment-specific mechanisms mainly restricted to the lowest masses.
Abstract
Background
The previous model-based cost-effectiveness analyses regarding elective oocyte cryopreservation remained debatable, while the usage rate may influence the cost per live birth. The ...aim of this study is to disclose the usage and cost-effectiveness of the planned cryopreserved oocytes after oocyte thawing in real-world situations.
Methods
This was a retrospective single-center observational study. Women who electively cryopreserved oocytes and returned to thaw the oocytes were categorized as thawed group. The oocytes were fertilized at our center and the sperm samples for each individual was retrieved from their respective husbands. Clinical outcomes were traced and the cumulative live birth rate per thawed case was calculated. The costs from oocyte freezing cycles to oocyte thawing, and embryo transfer cycles were accordingly estimated. The cumulative cost per live birth was defined by the cumulative cost divided by the live births per thawed case.
Results
We recruited 645 women with 840 oocyte retrieval cycles for elective oocyte freezing from November 2002 to December 2020. The overall usage rate was 8.4% (54/645). After the storage duration exceeded ten years, the probabilities of thawing oocytes were 10.6%, 26.6%, and 12.7% from women who cryopreserved their oocytes at the age ≤ 35 years, 36–39 years, and ≥ 40 years, respectively (
P
= 0.304). Among women who thawed their oocytes, 31.5% (17/54) of women achieved at least one live birth. For the age groups of ≤ 35 years, 36–39 years, and ≥ 40 years, the cumulative live birth rates per thawed case were 63.6%, 42.3%, and 17.6%, respectively (
P
= 0.045), and the cumulative costs for one live birth were $11,704, $17,189, and $35,642, respectively (
P
< 0.001).
Conclusions
The overall usage rate was 8.4% in our cohort. The cumulative live birth rate was greatest in the youngest group and the cumulative cost per live birth was highest in the oldest group, which was threefold greater than that in the group aged ≤ 35 years. The findings added to the limited evidence of the usage rate in real-world situations, which could hopefully aid future analysis and decision-making in public health policy and for women willing to preserve fertility.
Trial registration
None.
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