Prospektive Studie zur Validierung eines computergestützten Auswerteprogramms bei der Diagnostik des Schildwächterlymphknotens mittels fusionierter SPECT/CT: Bildgebung beim Prostatakarzinom

Die Anwendung computergestützter Diagnoseprogramme nimmt in der diagnostischen Radiologie und Nuklearmedizin eine zunehmend größere Rolle ein. Ziel dieser Arbeit ist die Bewertung des computergestützten Auswertesystems InterView Fusion, das in Zusammenarbeit mit Mitarbeitern der Firma Mediso, Ungarn, und der Klinik für Nuklearmedizin des Universitätsklinikums Schleswig-Holsteins, Campus Kiel, entwickelt wurde. In dieser Studie wurde das Programm auf die Auswertung von fusionierter SPECT/CT-Bildgebung zur Detektion der Schildwächterlymphknoten (SLN) bei Prostatakarzinompatienten angewendet. Es wurde untersucht, inwieweit das zu überprüfende Programm in der Lage ist mittels der SPECT/CT-Bildgebung den Lymphabfluss zu interpretieren. 72 Patienten mit stanzbioptisch gesichertem Prostatakarzinom wurden in die Studie eingeschlossen. Als Referenzstandard wurden die alleinigen fachärztlichen Befunde der SPECT/CT-Datensätze vorausgesetzt. Alle von InterViewTM Fusion detektierten Traceranreicherungen wurden visuell durch 2 erfahrene Fachärzte für Nuklearmedizin im Konsens beurteilt und so die Entscheidung für oder gegen das Vorliegen eines SLN gefällt. Anhand dieser Ergebnisse wurden anschließend eine Sensitivität von 78,1 Prozent und Spezifität von 84,4 Prozent der Software berechnet. Die falsch-negative Ratio betrug 0,22, die falsch-positiv Ratio 0,16. Die Anwendbarkeit des computergestützten Auswerteprogramms InterView Fusion für die SLN-Diagnostik beim Prostatakarzinom mittels SPECT/CT-Bildgebung wurde im Rahmen dieser Studie bestätigt. Es trägt als unterstützendes Werkzeug zur Auswertung von SPECT/CT-Datensätzen im Rahmen der präinterventionellen Lymphknotendiagnostik bei, wobei weiterhin eine Kontrolle und Korrektur der Ergebnisse durch erfahrene Ärzte erforderlich ist. Mit fortschreitender Verbesserung können in der diagnostischen Nuklearmedizin, insbesondere bei anatomisch komplexen Gegebenheiten wie in unserer Arbeit im Zielgebiet des Lymphabflusses im kleinen Becken, immer mehr und präziser SLN unter der Zuhilfenahme eines Diagnoseprogramms beschrieben werden

On the Importance of Calibration in Semi-supervised Learning

State-of-the-art (SOTA) semi-supervised learning (SSL) methods have been highly successful in leveraging a mix of labeled and unlabeled data by combining techniques of consistency regularization and pseudo-labeling. During pseudo-labeling, the model's predictions on unlabeled data are used for training and thus, model calibration is important in mitigating confirmation bias. Yet, many SOTA methods are optimized for model performance, with little focus directed to improve model calibration. In this work, we empirically demonstrate that model calibration is strongly correlated with model performance and propose to improve calibration via approximate Bayesian techniques. We introduce a family of new SSL models that optimizes for calibration and demonstrate their effectiveness across standard vision benchmarks of CIFAR-10, CIFAR-100 and ImageNet, giving up to 15.9% improvement in test accuracy. Furthermore, we also demonstrate their effectiveness in additional realistic and challenging problems, such as class-imbalanced datasets and in photonics science.Comment: 24 page

Multi-Symmetry Ensembles: Improving Diversity and Generalization via Opposing Symmetries

Deep ensembles (DE) have been successful in improving model performance by learning diverse members via the stochasticity of random initialization. While recent works have attempted to promote further diversity in DE via hyperparameters or regularizing loss functions, these methods primarily still rely on a stochastic approach to explore the hypothesis space. In this work, we present Multi-Symmetry Ensembles (MSE), a framework for constructing diverse ensembles by capturing the multiplicity of hypotheses along symmetry axes, which explore the hypothesis space beyond stochastic perturbations of model weights and hyperparameters. We leverage recent advances in contrastive representation learning to create models that separately capture opposing hypotheses of invariant and equivariant functional classes and present a simple ensembling approach to efficiently combine appropriate hypotheses for a given task. We show that MSE effectively captures the multiplicity of conflicting hypotheses that is often required in large, diverse datasets like ImageNet. As a result of their inherent diversity, MSE improves classification performance, uncertainty quantification, and generalization across a series of transfer tasks.Comment: Camera Ready Revision. ICML 202

Constructive Assimilation: Boosting Contrastive Learning Performance through View Generation Strategies

Transformations based on domain expertise (expert transformations), such as random-resized-crop and color-jitter, have proven critical to the success of contrastive learning techniques such as SimCLR. Recently, several attempts have been made to replace such domain-specific, human-designed transformations with generated views that are learned. However for imagery data, so far none of these view-generation methods has been able to outperform expert transformations. In this work, we tackle a different question: instead of replacing expert transformations with generated views, can we constructively assimilate generated views with expert transformations? We answer this question in the affirmative and propose a view generation method and a simple, effective assimilation method that together improve the state-of-the-art by up to ~3.6% on three different datasets. Importantly, we conduct a detailed empirical study that systematically analyzes a range of view generation and assimilation methods and provides a holistic picture of the efficacy of learned views in contrastive representation learning.Comment: Accepted at Generative Models for Computer Vision Workshop 202

Measurements of prompt charm production cross-sections in pp collisions at s=5 TeV

Production cross-sections of prompt charm mesons are measured using data from pp collisions at the LHC at a centre-of-mass energy of 5 TeV. The data sample corresponds to an integrated luminosity of 8.60 ± 0.33 pb−1 collected by the LHCb experiment. The production cross-sections of D0, D+, Ds+, and D∗+ mesons are measured in bins of charm meson transverse momentum, pT, and rapidity, y. They cover the rapidity range 2.0 < y < 4.5 and transverse momentum ranges 0 < pT< 10 GeV/c for D0 and D+ and 1 < pT< 10 GeV/c for Ds+ and D∗+ mesons. The inclusive cross-sections for the four mesons, including charge-conjugate states, within the range of 1 < pT< 8 GeV/c are determined to be σpp→D0X=1004±3±54μb,σpp→D+X=402±2±30μb,σpp→Ds+X=170±4±16μb,σpp→D∗+X=421±5±36μb, where the uncertainties are statistical and systematic, respectively

Measurement of the properties of the Ξb∗ 0 baryon

We perform a search for near-threshold Ξb0 resonances decaying to Ξb−π+ in a sample of proton-proton collision data corresponding to an integrated luminosity of 3 fb−1 collected by the LHCb experiment. We observe one resonant state, with the following properties: mΞb∗0−mΞb−−mπ+=15.727±0.068stat±0.023systMeV/c2ΓΞb∗0=0.90±0.16stat±0.08systMeV.This confirms the previous observation by the CMS collaboration. The state is consistent with the JP = 3/2+ Ξb∗ 0 resonance expected in the quark model. This is the most precise determination of the mass and the first measurement of the natural width of this state. We have also measured the ratio σpp→Ξb∗0XℬΞb∗0→Ξb−π+σpp→Ξb−X=0.28±0.03stat.±0.01syst.

Observation of Λb0 → ψ(2S)pK− and Λb0 → J/ψπ+π−pK− decays and a measurement of the Λb0 baryon mass

The decays Λb0 → ψ(2S)pK− and Λb0 → J/ψπ+π−pK− are observed in a data sample corresponding to an integrated luminosity of 3 fb−1, collected in proton-proton collisions at 7 and 8 TeV centre-of-mass energies by the LHCb detector. The ψ(2S) mesons are reconstructed through the decay modes ψ(2S) → μ+μ− and ψ(2S) → J/ψπ+π−.The branching fractions relative to that of Λb0 → J/ψpK− are measured to be ℬΛb0→ψ2SpK−ℬΛb0→J/ψpK−=20.70±0.76±0.46±0.37×10−2, where the first uncertainties are statistical, the second are systematic and the third is related to the knowledge of J/ψ and ψ(2S) branching fractions. The mass of the Λb0 baryon is measured to be MΛb0=5619.65±0.17±0.17MeV/c2, where the uncertainties are statistical and systematic

Measurement of the B± production cross-section in pp collisions at s=7 and 13 TeV

The production of B± mesons is studied in pp collisions at centre-of-mass energies of 7 and 13 TeV, using B± → J/ψ K± decays and data samples corresponding to 1.0 fb−1 and 0.3 fb−1, respectively. The production cross-sections summed over both charges and integrated over the transverse momentum range 0 < pT < 40 GeV/c and the rapidity range 2.0 < y < 4.5 are measured to be σpp→B±X,s=7TeV=43.0±0.2±2.5±1.7μb, σpp→B±X,s=13TeV=86.6±0.5±5.4±3.4μb, where the first uncertainties are statistical, the second are systematic, and the third are due to the limited knowledge of the B± → J/ψ K± branching fraction. The ratio of the cross-section at 13 TeV to that at 7 TeV is determined to be 2.02 ± 0.02 (stat) ± 0.12 (syst). Differential cross-sections are also reported as functions of pT and y. All results are in agreement with theoretical calculations based on the state-of-art fixed next-to-leading order quantum chromodynamics