48 research outputs found

    Blooming Artifact Reduction in Coronary Artery Calcification by A New De-blooming Algorithm: Initial Study

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    The aim of this study was to investigate the use of de-blooming algorithm in coronary CT angiography (CCTA) for optimal evaluation of calcified plaques. Calcified plaques were simulated on a coronary vessel phantom and a cardiac motion phantom. Two convolution kernels, standard (STND) and high-definition standard (HD STND), were used for imaging reconstruction. A dedicated de-blooming algorithm was used for imaging processing. We found a smaller bias towards measurement of stenosis using the deblooming algorithm (STND: bias 24.6% vs 15.0%, range 10.2% to 39.0% vs 4.0% to 25.9%; HD STND: bias 17.9% vs 11.0%, range 8.9% to 30.6% vs 0.5% to 21.5%). With use of de-blooming algorithm, specificity for diagnosing significant stenosis increased from 45.8% to 75.0% (STND), from 62.5% to 83.3% (HD STND); while positive predictive value (PPV) increased from 69.8% to 83.3% (STND), from 76.9% to 88.2% (HD STND). In the patient group, reduction in calcification volume was 48.1 ± 10.3%, reduction in coronary diameter stenosis over calcified plaque was 52.4 ± 24.2%. Our results suggest that the novel de-blooming algorithm could effectively decrease the blooming artifacts caused by coronary calcified plaques, and consequently improve diagnostic accuracy of CCTA in assessing coronary stenosis

    Oestrogen receptor β and neoadjuvant therapy with tamoxifen: prediction of response and effects of treatment

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    In order to elucidate the relative importance of oestrogen receptor (ER)α, ERβ and an ERβ variant (ERβ2/βcx) in the response of breast cancers to tamoxifen, tumour levels of each receptor were assessed in 36 patients before and after 3 months of neoadjuvant treatment with tamoxifen (20 mg daily). All patients were postmenopausal women presenting with large ERα-positive breast cancers. Clinical response to treatment was assessed by tumour volume changes as determined from sequential ultrasounds and pathological response by comparison of the tumour morphology before and after treatment. Of 33 cases, 23 (70%) were classified as having a clinical response and 16 (48%) as having a response pathologically. All tumours stained positively for ERα and ERβ and 15 out of 33 (45%) for ERβ2/βcx. There were no significant differences in quantitative expression of any receptor between tumours that subsequently responded and that did not, whether response was assessed clinically or pathologically. Tamoxifen treatment was associated with a decrease in ERα, but an increase was the most frequent change (17 out of 33) in ERβ, and no consistent change was evident in staining of the ERβ2/βcx variant. In summary, ERβ1 and ERβ2/βcx variant protein are detected in ERα-positive breast tumours but their expression is not associated with a response to tamoxifen. Differential changes in ERα and ERβ were seen with treatment

    Euclid II. The VIS instrument

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    This paper presents the specification, design, and development of the Visible Camera (VIS) on the European Space Agency's mission. VIS is a large optical-band imager with a field of view of 0.54 deg2^2 sampled at with an array of 609 Megapixels and a spatial resolution of . It will be used to survey approximately 14 000 deg2^2 of extragalactic sky to measure the distortion of galaxies in the redshift range z=0.1z=0.1--1.5 resulting from weak gravitational lensing, one of the two principal cosmology probes leveraged by With photometric redshifts, the distribution of dark matter can be mapped in three dimensions, and the extent to which this has changed with look-back time can be used to constrain the nature of dark energy and theories of gravity. The entire VIS focal plane will be transmitted to provide the largest images of the Universe from space to date, specified to reach AB with a signal-to-noise ratio S/N in a single broad E (r+i+z)bandoverasixyearsurvey.Theparticularlychallengingaspectsoftheinstrumentarethecontrolandcalibrationofobservationalbiases,whichleadtostringentperformancerequirementsandcalibrationregimes.Withitscombinationofspatialresolution,calibrationknowledge,depth,andareacoveringmostoftheextraGalacticsky,VISwillalsoprovidealegacydatasetformanyotherfields.ThispaperdiscussestherationalebehindtheconceptionofVISanddescribestheinstrumentdesignanddevelopment,beforereportingtheprelaunchperformancederivedfromgroundcalibrationsandbriefresultsfromtheinorbitcommissioning.VISshouldreachfainterthanAB=25 band over a six-year survey. The particularly challenging aspects of the instrument are the control and calibration of observational biases, which lead to stringent performance requirements and calibration regimes. With its combination of spatial resolution, calibration knowledge, depth, and area covering most of the extra-Galactic sky, VIS will also provide a legacy data set for many other fields. This paper discusses the rationale behind the conception of VIS and describes the instrument design and development, before reporting the prelaunch performance derived from ground calibrations and brief results from the in-orbit commissioning. VIS should reach fainter than AB =25 with S/N10 S/N 10 for galaxies with a full width at half maximum of in a diameter aperture over the Wide Survey, and mABforaDeepSurveythatwillcovermorethan50degm_ AB for a Deep Survey that will cover more than 50 deg^2$. The paper also describes how the instrument works with the telescope and survey, and with the science data processing, to extract the cosmological information

    Adaption eines Instruments zur Erfassung der "AI Readiness" bei Medizinstudierenden

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