Dynamic prediction of mortality in COVID-19 patients in the intensive care unit: A retrospective multi-center cohort study

Background

The COVID-19 pandemic continues to overwhelm intensive care units (ICUs) worldwide, and improved prediction of mortality among COVID-19 patients could assist decision making in the ICU setting. In this work, we report on the development and validation of a dynamic mortality model specifically for critically ill COVID-19 patients and discuss its potential utility in the ICU.

Methods

We collected electronic medical record (EMR) data from 3222 ICU admissions with a COVID-19 infection from 25 different ICUs in the Netherlands. We extracted daily observations of each patient and fitted both a linear (logistic regression) and non-linear (random forest) model to predict mortality within 24 h from the moment of prediction. Isotonic regression was used to re-calibrate the predictions of the fitted models. We evaluated the models in a leave-one-ICU-out (LOIO) cross-validation procedure.

Results

The logistic regression and random forest model yielded an area under the receiver operating characteristic curve of 0.87 [0.85; 0.88] and 0.86 [0.84; 0.88], respectively. The recalibrated model predictions showed a calibration intercept of −0.04 [−0.12; 0.04] and slope of 0.90 [0.85; 0.95] for logistic regression model and a calibration intercept of −0.19 [−0.27; −0.10] and slope of 0.89 [0.84; 0.94] for the random forest model.

Discussion

We presented a model for dynamic mortality prediction, specifically for critically ill COVID-19 patients, which predicts near-term mortality rather than in-ICU mortality. The potential clinical utility of dynamic mortality models such as benchmarking, improving resource allocation and informing family members, as well as the development of models with more causal structure, should be topics for future research.

Free propagation phase-contrast breast CT provides higher image quality than cone-beam breast-CT at low radiation doses: a feasibility study on human mastectomies

In this study we demonstrate the first direct comparison between synchrotron x-ray propagation-based CT (PB-CT) and cone-beam breast-CT (CB-CT) on human mastectomy specimens (N = 12) including different benign and malignant lesions. The image quality and diagnostic power of the obtained data sets were compared and judged by two independent expert radiologists. Two cases are presented in detail in this paper including a comparison with the corresponding histological evaluation. Results indicate that with PB-CT it is possible to increase the level of contrast-to-noise ratio (CNR) keeping the same level of dose used for the CB-CT or achieve the same level of CNR reached by CB-CT at a lower level of dose. In other words, PB-CT can achieve a higher diagnostic potential compared to the commercial breast-CT system while also delivering a considerably lower mean glandular dose. Therefore, we believe that PB-CT technique, if translated to a clinical setting, could have a significant impact in improving breast cancer diagnosis.

Clinical application of low-dose phase contrast breast CT: methods for the optimization of the reconstruction workflow

Results are presented of a feasibility study of three-dimensional X-ray tomographic mammography utilising in-line phase contrast. Experiments were performed at SYRMEP beamline of Elettra synchrotron. A specially designed plastic phantom and a mastectomy sample containing a malignant lesion were used to study the reconstructed image quality as a function of different image processing operations. Detailed evaluation and optimization of image reconstruction workflows have been carried out using combinations of several advanced computed tomography algorithms with different pre-processing and post-processing steps. Special attention was paid to the effect of phase retrieval on the diagnostic value of the reconstructed images. A number of objective image quality indices have been applied for quantitative evaluation of the results, and these were compared with subjective assessments of the same images by three experienced radiologists and one pathologist. The outcomes of this study provide practical guidelines for the optimization of image processing workflows in synchrotron-based phase-contrast mammo-tomography.

Measurement of the B0 production cross section in pp collisions at sqrt[s] = 7 TeV

Measurements of the differential production cross sections dσ/dpTB and dσ/dyB for B0 mesons produced in pp collisions at sqrt[s] = 7 TeV are presented. The data set used was collected by the CMS experiment at the LHC and corresponds to an integrated luminosity of 40 pb-1. The production cross section is measured from B0 meson decays reconstructed in the exclusive final state J/ψKS0, with the subsequent decays J/ψ → μ + μ - and KS0 → π+}π-. The total cross section for pTB>5 GeV and |yB|<2.2 is measured to be 33.2 ± 2.5 ± 3.5 μb, where the first uncertainty is statistical and the second is systematic.

Search for neutral minimal supersymmetric standard model Higgs bosons decaying to tau pairs in pp collisions at √s=7 TeV

A search for neutral minimal supersymmetric standard model (MSSM) Higgs bosons in pp collisions at the LHC at a center-of-mass energy of 7 TeV is presented. The results are based on a data sample corresponding to an integrated luminosity of 36  pb(-1) recorded by the CMS experiment. The search uses decays of the Higgs bosons to tau pairs. No excess is observed in the tau-pair invariant-mass spectrum. The resulting upper limits on the Higgs boson production cross section times branching fraction to tau pairs, as a function of the pseudoscalar Higgs boson mass, yield stringent new bounds in the MSSM parameter space.

Search for supersymmetry in pp collisions at √7 TeV in events with two photons and missing transverse energy

A search for supersymmetry in the context of general gauge-mediated breaking with the lightest neutralino as the next-to-lightest supersymmetric particle and the gravitino as the lightest is presented. The data sample corresponds to an integrated luminosity of 36 pb(-1) recorded by the CMS experiment at the LHC. The search is performed by using events containing two or more isolated photons, at least one hadronic jet, and significant missing transverse energy. No excess of events at high missing transverse energy is observed. Upper limits on the signal cross section for general gauge-mediated supersymmetry between 0.3 and 1.1 pb at the 95% confidence level are determined for a range of squark, gluino, and neutralino masses, excluding supersymmetry parameter space that was inaccessible to previous experiments.

Study of Z Boson Production in PbPb Collisions at √S(NN)=2.76 TeV

A search for Z bosons in the μ(+)μ(-) decay channel has been performed in PbPb collisions at √S(NN)=2.76  TeV with the CMS detector at the LHC, in a 7.2 μb(-1) data sample. The number of opposite-sign muon pairs observed in the 60-120 GeV/c(2) invariant mass range is 39, corresponding to a yield per unit of rapidity (y) and per minimum bias event of [33.8±5.5(stat)±4.4(syst)]×10(-8), in the |y|<2.0 range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions.

The mammography project at the SYRMEP beamline

A clinical program for X-ray phase contrast (PhC) mammography with synchrotron radiation (SR) has been started in March 2006 at the SYRMEP beamline of Elettra, the SR facility in Trieste, Italy. The original beamline layout has been modified substantially and a clinical facility has been realized. In order to fulfill all security requirements, dedicated systems have been designed and implemented, following redundancy criteria and "fail safe" philosophy. Planar radiographic images are obtained by scanning simultaneously the patient and the detector through the stationary and laminar SR beam. In this first phase of the project a commercial screen-film system has been used as image receptor. Upon approval by the respective authorities, the mammography program is about half way to conclusion. Up to now about 50 patients have been examined. The patients are volunteers recruited by the radiologist after conventional examinations at the hospital resulted in an uncertain diagnosis. As an example one case of PhC SR mammography is shown and compared to conventional digital mammography. Preliminary analysis shows the high diagnostic quality of the PhC SR images that were acquired with equal or less delivered dose compared to the conventional ones.

Generation of GW radiation pulses from a VUV free-electron laser operating in the femtosecond regime

Experimental results are presented from vacuum-ultraviolet free-electron laser (FEL) operating in the self-amplified spontaneous emission (SASE) mode. The generation of ultrashort radiation pulses became possible due to specific tailoring of the bunch charge distribution. A complete characterization of the linear and nonlinear modes of the SASE FEL operation was performed. At saturation the FEL produces ultrashort pulses (30-100 fs FWHM) with a peak radiation power in the GW level and with full transverse coherence. The wavelength was tuned in the range of 95-105 nm.

First observation of self-amplified spontaneous emission in a free-electron laser at 109 nm wavelength

We present the first observation of self-amplified spontaneous emission (SASE) in a free-electron laser (FEL) in the vacuum ultraviolet regime at 109 nm wavelength (11 eV). The observed free-electron laser gain (approximately 3000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width, and intensity fluctuations, are all consistent with the present models for SASE FELs.

[Role of the Doppler technique in the differential diagnosis of solid breast nodules. Personal experience]

The role of Doppler techniques in the differential diagnosis of benign from malignant solid breast lesions remains to be defined; indeed, it is still debated whether the diagnostic findings of Doppler US add further information to mammographic and B-mode US results. We investigated the diagnostic effectiveness of Doppler techniques in the differential diagnosis of breast nodules, especially in a selected group of patients with questionable diagnosis because of atypical morphological features or benign appearance detected in women over 40 years old. Color Doppler studies were performed on 111 breast nodules with solid features at US; 53 vascularized lesions were also studied with duplex Doppler. All the nodules were submitted to biopsy, which demonstrated 6 nonvascularized lesions to be complicated cysts. There were 105 solid breast nodules (65 benign and 40 malignant). Color Doppler US showed vascular signals in 71% of benign nodules, mainly at the periphery. 12% of benign nodules had Doppler signals of malignancy at color Doppler US; 92% of malignant lesions was vascularized, with irregular intratumoral signals in 37% of them. The peak systolic velocity and the resistive index were higher in malignant tumors (p < 0.02); peak systolic velocity changed in malignant lesions according to tumor size (p < 0.01). Color Doppler correctly suspected malignancy in 62% of the nodules with questionable features; conversely, 31% of the nodules with questionable findings and no color Doppler signs of malignancy proved malignant at biopsy. In conclusion, the role of Doppler studies remains currently limited in the differential diagnosis of solid breast lesions.

[The diagnostic contribution of direct radiographic enlargement and of echography in the study of breast neoplasms]

To compare the diagnostic value and the role of plain radiographic magnification and of ultrasonography (US) in breast cancer evaluation, 83 malignant tumors were studied with mammography, plain radiographic magnification and US. Microcalcifications were not included in our study. All tumors subsequently underwent histology or cytology. In our series, the malignant nature of the lesion was unquestionably proved in 53% of cases while a possible malignancy was suspected in 36% and a benign nature was incorrectly suspected in 11% of cases with mammography. The diagnostic value of plain radiographic magnification was compared with that of US; breast patterns, mammographic and clinical findings were considered. As for breast patterns, plain radiographic magnification was more accurate in evaluating fatty breast than both mammography and US, allowing the correct diagnosis of 58% of questionable mammographic findings, vs. 33% of US. On the contrary, US was more accurate in dense breasts, allowing the correct diagnosis of 77.7% of mammographic misdiagnoses vs. 33.3% only of plain radiographic magnification. As far as mammography is concerned, US was more accurate than plain radiographic magnification in the assessment of round masses (71.4% vs. 38.1%, respectively), whereas plain radiographic magnification was more accurate than US in stellate masses (100% vs. 92.7%, respectively). As far as clinical findings are concerned, plain radiographic magnification sensitivity was substantially the same in the assessment of symptomatic and asymptomatic lesions (91.5% vs. 89%, respectively), whereas US sensitivity was higher in symptomatic (97%) than in asymptomatic (69%) lesions. The rate of false-negative US diagnoses (14.4%) was higher than those of mammography and of plain radiographic magnification. Negative US findings must be considered with caution and are not sufficient to settle a radiologic doubt.