45 research outputs found
Reliable brain morphometry from contrast-enhanced T1w-MRI in patients with multiple sclerosis.
Brain morphometry is usually based on non-enhanced (pre-contrast) T1-weighted MRI. However, such dedicated protocols are sometimes missing in clinical examinations. Instead, an image with a contrast agent is often available. Existing tools such as FreeSurfer yield unreliable results when applied to contrast-enhanced (CE) images. Consequently, these acquisitions are excluded from retrospective morphometry studies, which reduces the sample size. We hypothesize that deep learning (DL)-based morphometry methods can extract morphometric measures also from contrast-enhanced MRI. We have extended DL+DiReCT to cope with contrast-enhanced MRI. Training data for our DL-based model were enriched with non-enhanced and CE image pairs from the same session. The segmentations were derived with FreeSurfer from the non-enhanced image and used as ground truth for the coregistered CE image. A longitudinal dataset of patients with multiple sclerosis (MS), comprising relapsing remitting (RRMS) and primary progressive (PPMS) subgroups, was used for the evaluation. Global and regional cortical thickness derived from non-enhanced and CE images were contrasted to results from FreeSurfer. Correlation coefficients of global mean cortical thickness between non-enhanced and CE images were significantly larger with DL+DiReCT (r = 0.92) than with FreeSurfer (r = 0.75). When comparing the longitudinal atrophy rates between the two MS subgroups, the effect sizes between PPMS and RRMS were higher with DL+DiReCT both for non-enhanced (d = -0.304) and CE images (d = -0.169) than for FreeSurfer (non-enhanced d = -0.111, CE d = 0.085). In conclusion, brain morphometry can be derived reliably from contrast-enhanced MRI using DL-based morphometry tools, making additional cases available for analysis and potential future diagnostic morphometry tools
Late gadolinium enhancement and adverse outcomes in a contemporary cohort of adult survivors of tetralogy of Fallot
Objective:
Myocardial fibrosis has been associated with poorer outcomes in tetralogy of Fallot, however only a handful of studies have assessed its significance in the current era. Our aim was to quantify the amount of late gadolinium enhancement in both the LV and RV in a contemporary cohort of adults with surgically repaired tetralogy of Fallot, and assess the relationship with adverse clinical outcomes.
Design:
Single centre cohort study
Setting:
National tertiary referral center
Patients: One hundred fourteen patients with surgically repaired tetralogy of Fallot with median age 29.5 years (range 17.5-64.2). Prospective follow-up for mean 2.4 years (SD 1.29).
Interventions:
Cardiovascular magnetic resonance was performed, and late gadolinium enhancement mass was estimated for the LV using the 5-SD remote myocardium method, and for the RV using a segmental scoring system. Cohort characterization was determined through the use of a computerized database.
Outcome measures:
Survival analysis from time of scan to first adverse event, defined as an episode of atrial arrhythmia, sustained ventricular arrhythmia, hospitalization with heart failure, or implantable cardioverter-defibrillator insertion.
Results:
Eleven patients experienced an adverse outcome in the follow-up period, although there were no deaths. LV late gadolinium enhancement was associated with adverse outcomes in a univariate model (P = .027). However, when adjusted for age at scan the significant variables included NYHA class (P = .006), peak oxygen uptake (P = .028), number of prior sternotomies (P = .044), and higher indexed RV and LV end diastolic volumes (P = .002 and P < .001), but not RV or LV late gadolinium enhancement.
Conclusions:
Formal quantification of late gadolinium enhancement is not currently as helpful in ascertaining prognosis compared to other, more easily assessed parameters in a contemporary cohort of tetralogy of Fallot survivors, however assessment particularly of the LV holds promise for the future
Hubble Space Telescope Imaging of the Circumnuclear Environments of the CfA Seyfert Galaxies: Nuclear Spirals and Fueling
We present archival Hubble Space Telescope images of the nuclear regions of
43 of the 46 Seyfert galaxies found in the volume-limited,
spectroscopically-complete CfA Redshift Survey sample. Using an improved method
of image contrast enhancement, we create detailed high-quality structure maps
that allow us to study the distributions of dust, star clusters, and
emission-line gas in the circumnuclear regions (100-1000 pc scales) and in the
associated host galaxy. Essentially all of these Seyfert galaxies have
circumnuclear dust structures with morphologies ranging from grand-design
two-armed spirals to chaotic dusty disks. In most Seyferts there is a clear
physical connection between the nuclear dust spirals on hundreds of parsec
scales and large-scale bars and spiral arms in the host galaxies proper. These
connections are particularly striking in the interacting and barred galaxies.
Such structures are predicted by numerical simulations of gas flows in barred
and interacting galaxies, and may be related to the fueling of AGN by matter
inflow from the host galaxy disks. We see no significant differences in the
circumnuclear dust morphologies of Seyfert 1s and 2s, and very few Seyfert 2
nuclei are obscured by large-scale dust structures in the host galaxies. If
Seyfert 2s are obscured Seyfert 1s, then the obscuration must occur on smaller
scales than those probed by HST.Comment: 29 pages, 11 figures. Accepted for publication in the ApJ. For
high-resolution figures see http://www.astronomy.ohio-state.edu/~pogge/CfA
Automatic detection of lesion load change in Multiple Sclerosis using convolutional neural networks with segmentation confidence
WFPC2 Observations of Compact Star Cluster Nuclei in Low Luminosity Spiral Galaxies
We have used the Wide Field Planetary Camera 2 aboard the Hubble Space
Telescope to image the compact star cluster nuclei of the nearby, late-type,
low-luminosity spiral galaxies NGC 4395, NGC 4242, and ESO 359-029. We also
analyze archival WFPC2 observations of the compact star cluster nucleus of M33.
A comparative analysis of the structural and photometric properties of these
four nuclei is presented. All of the nuclei are very compact, with luminosity
densities increasing at small radii to the resolution limit of our data. NGC
4395 contains a Seyfert 1 nucleus with a distinct bipolar structure and bright
associated filaments which are likely due to [OIII] emission. The M33 nucleus
has a complex structure, with elongated isophotes and possible signatures of
weak activity, including a jet-like component. The other two nuclei are not
known to be active, but share similar physical size scales and luminosities to
the M33 and NGC 4395 nuclei. The circumnuclear environments of all four of our
program galaxies are extremely diffuse, have only low-to-moderate star
formation, and appear to be devoid of large quantities of dust. The central
gravitational potentials of the galaxies are also quite shallow, making the
origin of these types of `naked' nuclei problematic.Comment: to appear in the July 1999 Astronomical Journal; 38 pages (Latex), 5
tables (postscript), 21 figures (gif); postscript versions of the figures may
be obtained via anonymous ftp at
ftp://ftp.cv.nrao.edu/NRAO-staff/lmatthew/lanl-nucle
Characterisation of ‘bog butter’ using a combination of molecular and isotopic techniques
Chinese traditional values and human rights: an empirical study among students in Shanghai
The United Nations Declaration of Human Rights clearly formulates its demands universally. When it comes to the concrete application of these rights, however, the claim for universality cannot remain unquestioned. The question that is asked is whether or not human rights fit into all cultural contexts, or if they are just another aspect of western cultural imperialism. This discussion is especially vivid in the Chinese context, where quite often Chinese values deriving from China’s traditions and religions are seen as either an obstacle or an alternative to human rights. It was the goal of this project to examine how Chinese religiosity, in particular Chinese traditional values, are related to human rights. Based on a quantitative empirical survey among 424 Chinese students in Shanghai I discovered two dimensions of traditional religious values. The two dimensions were labeledli (ritual property) and ren (forbearance). Whereas li describes interpersonal, hierarchical, and active values, ren stands for more inwardly oriented, fatalistic and passive values. Li values correlate positively with the support for human rights, as most students have a very hierarchical understanding of human rights. The study has also shown that human rights only make sense to those who truly believe in the possibility of social change. Consequently ren values do not seem compatible with the human rights idea, as they promote a very passive and rather fatalistic worldview. An other result of this study is the fact, that being religious has no direct influence on one’s attitude towards human rights: Being religious is coupled with support for both li and ren values, which have opposite relations with the support for human rights. The study allows the conclusion that a wider and more complete human rights understanding, which includes both hierarchical and egalitarian aspects, would have the capacity to integrate both value dimension. A view which is absolutely in line with the ideas proclaimed in the Universal Declaration of Human Rights