Automated cardiovascular risk categorization through AI-driven coronary calcium quantification in cardiac PET acquired attenuation correction CT.

BACKGROUND: We present an automatic method for coronary artery calcium (CAC) quantification and cardiovascular risk categorization in CT attenuation correction (CTAC) scans acquired at rest and stress during cardiac PET/CT. The method segments CAC according to visual assessment rather than the commonly used CT-number threshold. METHODS: The method decomposes an image containing CAC into a synthetic image without CAC and an image showing only CAC. Extensive evaluation was performed in a set of 98 patients, each having rest and stress CTAC scans and a dedicated calcium scoring CT (CSCT). Standard manual calcium scoring in CSCT provided the reference standard. RESULTS: The interscan reproducibility of CAC quantification computed as average absolute relative differences between CTAC and CSCT scan pairs was 75% and 85% at rest and stress using the automatic method compared to 121% and 114% using clinical calcium scoring. Agreement between automatic risk assessment in CTAC and clinical risk categorization in CSCT resulted in linearly weighted kappa of 0.65 compared to 0.40 between CTAC and CSCT using clinically used calcium scoring. CONCLUSION: The increased interscan reproducibility achieved by our method may allow routine cardiovascular risk assessment in CTAC, potentially relieving the need for dedicated CSCT.

Candidate Electromagnetic Counterpart to the Binary Black Hole Merger Gravitational-Wave Event S190521g.

We report the first plausible optical electromagnetic counterpart to a (candidate) binary black hole merger. Detected by the Zwicky Transient Facility, the electromagnetic flare is consistent with expectations for a kicked binary black hole merger in the accretion disk of an active galactic nucleus [B. McKernan, K. E. S. Ford, I. Bartos et al., Astrophys. J. Lett. 884, L50 (2019)AJLEEY2041-821310.3847/2041-8213/ab4886] and is unlikely [

The prognostic value of visual and automatic coronary calcium scoring from low-dose computed tomography-[15O]-water positron emission tomography.

AIMS: The study aimed, firstly, to validate automatically and visually scored coronary artery calcium (CAC) on low-dose computed tomography (CT) (LDCT) scans with a dedicated calcium scoring CT (CSCT) scan and, secondly, to assess the added value of CAC scored from LDCT scans acquired during [15O]-water-positron emission tomography (PET) myocardial perfusion imaging (MPI) on prediction of major adverse cardiac events (MACE). METHODS AND RESULTS: Five hundred seventy-two consecutive patients with suspected coronary artery disease, who underwent [15O]-water-PET MPI with LDCT and a dedicated CSCT scan were included. In the reference CSCT scans, manual CAC scoring was performed, while LDCT scans were scored visually and automatically using deep learning approach. Subsequently, based on CAC score results from CSCT and LDCT scans, each patient's scan was assigned to one out of five cardiovascular risk groups (0, 1-100, 101-400, 401-1000, >1000), and the agreement in risk group classification between CSCT and LDCT scans was investigated. MACE was defined as a composite of all-cause death, non-fatal myocardial infarction, coronary revascularization, and unstable angina. The agreement in risk group classification between reference CSCT manual scoring and visual/automatic LDCT scoring from LDCT was 0.66 [95% confidence interval (CI): 0.62-0.70] and 0.58 (95% CI: 0.53-0.62), respectively. Based on visual and automatic CAC scoring from LDCT scans, patients with CAC > 100 and CAC > 400, respectively, were at increased risk of MACE, independently of ischaemic information from the [15O]-water-PET scan. CONCLUSION: There is a moderate agreement in risk classification between visual and automatic CAC scoring from LDCT and reference CSCT scans. Visual and automatic CAC scoring from LDCT scans improve identification of patients at higher risk of MACE.

SIFTING FOR SAPPHIRES: SYSTEMATIC SELECTION OF TIDAL DISRUPTION EVENTS IN iPTF.

We present results from a systematic selection of tidal disruption events (TDEs) in a wide-area (4800 deg2), g + R band, Intermediate Palomar Transient Factory (iPTF) experiment. Our selection targets typical optically-selected TDEs: bright (>60% flux increase) and blue transients residing in the center of red galaxies. Using photometric selection criteria to down-select from a total of 493 nuclear transients to a sample of 26 sources, we then use follow-up UV imaging with the Neil Gehrels Swift Telescope, ground-based optical spectroscopy, and light curve fitting to classify them as 14 Type Ia supernovae (SNe Ia), 9 highly variable active galactic nuclei (AGNs), 2 confirmed TDEs, and 1 potential core-collapse supernova. We find it possible to filter AGNs by employing a more stringent transient color cut (g - r < -0.2 mag); further, UV imaging is the best discriminator for filtering SNe, since SNe Ia can appear as blue, optically, as TDEs in their early phases. However, when UV-optical color is unavailable, higher precision astrometry can also effectively reduce SNe contamination in the optical. Our most stringent optical photometric selection criteria yields a 4.5:1 contamination rate, allowing for a manageable number of TDE candidates for complete spectroscopic follow-up and real-time classification in the ZTF era. We measure a TDE per galaxy rate of 1.7 - 1.3 + 2.9 × 10 - 4 gal - 1 yr - 1 (90% CL in Poisson statistics). This does not account for TDEs outside our selection criteria, thus may not reflect the total TDE population, which is yet to be fully mapped.

A radio jet from the optical and x-ray bright stellar tidal disruption flare ASASSN-14li.

The tidal disruption of a star by a supermassive black hole leads to a short-lived thermal flare. Despite extensive searches, radio follow-up observations of known thermal stellar tidal disruption flares (TDFs) have not yet produced a conclusive detection. We present a detection of variable radio emission from a thermal TDF, which we interpret as originating from a newly launched jet. The multiwavelength properties of the source present a natural analogy with accretion-state changes of stellar mass black holes, which suggests that all TDFs could be accompanied by a jet. In the rest frame of the TDF, our radio observations are an order of magnitude more sensitive than nearly all previous upper limits, explaining how these jets, if common, could thus far have escaped detection.

[Root canal treatment. Quality and result]. / De wortelkanaalbehandeling. Kwaliteit en resultaat.

The correlation of root canal treatment quality and the probability of healing of apical periodontitis are discussed. Noted is the often large discrepancy between treatment outcomes observed in prospective studies and those obtained in cross-sectional studies of general populations. Looking for improvement of the latter, those treatment shortcomings are discussed which have a known or suspected negative impact on the probability of healing or preventing periapical pathology.

Influence of hypercapnia and hypoxia on rabbit platelet aggregation.

The influence of changes in pCO2, pH and pO2 on the aggregation of rabbit blood platelets was studied in vitro, with emphasis on hypercapnia, acidosis and hypoxia. Hypercapnia combined with acidosis caused a reduction in rabbit platelet aggregation, as induced by collagen, thrombin and ADP; the effect being most pronounced with collagen and smallest with ADP. Hypoxia reduced thrombin induced platelet aggregation, but had no effect on ADP and collagen induced aggregation. Synergistic activation of rabbit platelets, as induced by the addition of serotonin to platelet rich plasma together with collagen or ADP, seemed to be equally sensitive to changes in pCO2 and pH as activation by the individual agents, and insensitive to changes in pO2.

The influence of prostaglandins on leukocyte-endothelium interactions in rabbit mesenteric venules.

Contradictory results have been reported concerning the effects of prostaglandins (PGs) on leukocyte-endothelium interactions. Therefore, we investigated the in vivo effects of PGE1, PGE2, Iloprost (a stable PGI2-analogue), and also of a combination of these PGs on leukocyte rolling and FMLP-induced leukocyte adhesion in venules of rabbit mesentery. This preparation was used because of its low level of vasoactivity, eliminating hemodynamic effects on leukocyte-endothelium interactions. The mesentery was superfused with PGs or vehicle. After 30 min FMLP was added to the PG-solution for 15 min, whereupon the tissue was superfused with the PG-solution alone for another 30 min. Neither the PGs nor the cocktail influenced leukocyte rolling. During FMLP administration leukocyte adhesion increased and leukocyte rolling decreased; adhesion was highest in the presence of PGE2. The FMLP-induced decrease in leukocyte rolling was similar in all groups. After FMLP administration had been stopped the number of adherent cells almost returned to baseline and the level of leukocyte rolling increased, the baseline level being reached only in the presence of PGE2. In conclusion, these findings indicate that the effects of PGs on leukocyte-endothelium interactions are limited.

Cross validation of model predicting (ir)regularity of dental attendance.

A theoretical model developed for the prediction of (ir)regular dental attendance was evaluated with loglinear models (logit approach). The model found is identical to the model developed previously. The prediction of (ir)regularity, however, proved to be unsatisfactory. The disappointing result is attributed to the difficulty of measuring the predictors adequately, and to the possibility that additional variables might be needed.

Regularity of dental attendance in the Netherlands related to preference for preservation of teeth.

In order to study the relationship between regularity of dental attendance and the value attached to the retaining of the teeth, a survey has been carried out among 25-yr-olds in Amsterdam. The value attached to retention was operationalized threefold and was analyzed with, among others, principal component analysis for discrete variables (HOMALS). It has been found that regular dental attenders, compared to irregulars, give a higher priority to retention of the teeth than to other items, are willing to spend a larger amount of money to prevent loss of the teeth, and have a greater aversion to full dentures at both the present age and when 50 yr old. These findings are discussed. Based upon measures of association between the three operationalizations of the value attached to retention of the teeth, it is suggested that these operationalizations deal with different aspects of the attitude towards full dentures.

Dental anxiety, the parental family and regularity of dental attendance.

A survey was carried out among 25-yr-old inhabitants of Amsterdam in order to study the relationship between regularity of dental attendance on the one hand and dental anxiety, dental upbringing of the respondents, dental behavior of the parents, education, sex, and the interactions between these independents, on the other. The data were analyzed hierarchically with regression analysis, the logistic approach. Dental anxiety, sex, dental upbringing and the interaction between education and anxiety, in that order, were found to be of importance for the prediction of regularity of dental attendance. Two other terms, though lacking substantial standardized regression coefficients, namely education and the interaction between education and dental upbringing, are also present in the model found. The prediction of one being a regular attender is satisfactory, but the classification of the irregular attenders is disappointing. The effect is discussed of the rather large non-response and attention is given to the effect of dental upbringing in regard to coping resources in the dental situation. It has to be concluded that other factors must be included to achieve an improvement of the classification of the irregular attenders. Dental anxiety, although of importance, cannot account for an adequate differentiation between regular and irregular attenders.

Value of the teeth.

A random sample of 542 respondents answered questions concerning the value assigned to the teeth, dental attendance pattern, oral health status, and dental anxiety. Non-linear multivariate analysis showed the data regarding value attached to the teeth to contain two dimensions, of which the second one was deleted due to extreme answer patterns (skewed distributions) on the pertinent variables. Repetition of the analysis, including a plot of the respondents, made it possible to discern four subsamples, characterized by specific answer patterns. In the discussion attention was given firstly to the separate variables estimating the value attached to the teeth, and next to the four subsamples, taking into consideration the dental attendance pattern, oral health status, and dental anxiety. It was concluded that the multivariate approach reveals that the respondents are of a rather high heterogeneity.

Personality traits of patients suffering extreme dental anxiety.

In order to investigate the relationship between dental anxiety and some personality traits, a group of 103 patients suffering extreme dental anxiety and therefore enrolled in a special treatment program were compared with controls sampled at random. The mean scores of the controls on dental anxiety measurements and on questionnaires dealing with personality traits were transformed into 50 with standard deviation equal to 10 to make them mutually comparable, and these subsequently were used as reference points, from which the likewise transformed mean scores of the anxiety group have to differ substantially if both groups stem from different populations. The mean scores were tested for difference with ANOVA. It appears that the anxious patients are more neurotic, i.e. more unstable, than the controls. Moreover, the patients feel themselves more uncertain with regard to having control, are less decisive, have a lower self-esteem, are less inclined to act and are, in general, anxious persons. These findings may have implications for selecting the most appropriate approach for amelioration of their anxiety or support of their coping capacity.

Differentiating regular from irregular dental attenders of either sex by linear discriminant analysis.

The present article describes an attempt to improve the prediction of dental attendance, results by using an additional number of variables and performing discriminant analyses, done separately for men and women. It appears that regular and irregular dental attenders might be discriminated on the basis of mathematically combined variables and interactions. The (number of) variables selected by the analysis to differentiate regular from irregular male attenders differ(s) from those selected for female attenders. About 80% of all respondents can be classified correctly, but this is largely due to the assignment of actual regulars to classified regulars. The use of differing sets of prior probabilities affects the classification results, namely, either the classification of the regulars or that of the irregulars improves. In the discussion attention is given to the seemingly contradictory results of the Mann-Whitney tests per variable on the one hand and the discriminant analyses on the other. In this connection, the finding that 'education' plays a different role for men than for women is discussed. The validity of the variable 'last visit' is dubious. It is concluded that when differentiating regulars from irregulars, a division of the respondents according to sex makes sense because of the (number of) variables associated with their regular dental attendance. Furthermore, it seems warranted to say that the classification of the irregulars fails because the reversed scores on the variables with which the regulars are classified don't contain all information needed for the prediction of irregular dental attendance. Lastly, notwithstanding the use of more variables in the present study, the results are not better than those in the previous one, in which just three factors were used.

Effect of a special dental program upon extreme dental anxiety.

Dental anxiety of 60 extremely anxious dental patients enrolled in a special program, was measured multioperationally before and immediately after treatment, and 6 months later. The mean anxiety level was substantially lowered during the course of treatment, indicating a favourable effect of the program. After 6 months dental anxiety was still at the lower level.

Three factors predicting irregular versus regular dental attendance: a model fitting to empirical data.

A tentative theory, based upon the results of a survey that was performed in an urbanized village in the Netherlands, and proposing that the (ir)regularity of dental attendance is predicted by 1) dental anxiety, 2) the family dental health pattern and 3) the preference for preservation of the teeth, has been explored with loglinear models (logit approach). It has been shown that dental anxiety in combination with preference for preservation of the teeth is significantly associated with the (ir)regularity, but the family dental health pattern has a modifying effect. The probabilities of being an irregular dental attender were estimated for the levels discernible in the two predictor variables and with the odds of irregular dental attendance corresponding 95% confidence intervals were approximated. The results were discussed and it seems warranted to conclude that (ir)regular dental attendance dependent on the levels of the variables, mentioned above, is predicted more or less accurately. A further exploration of the theory and the variables involved seems worthwhile.

Clinical measurement of dental anxiety.

The mean scores on five dental anxiety measurements of 60 patients suffering from extreme dental anxiety are compared with those of an equal-sized, matched group of regular dental attenders free from dental anxiety. Four of the measurements, especially Corah's DAS, appear to be suitable for distinguishing persons suffering from extreme dental anxiety. Also, persons with extreme dental anxiety appear to express their fear openly.

Influence of repression upon the measurement of dental anxiety.

Using a non-linear, multivariate analysis, the resistance against admitting to being dentally anxious was studied. Dental anxiety was found to be repressed by a subgroup, among them more men than women, of a sample, who also repressed the feeling of low self esteem about tooth loss. Based on the results, regular and irregular dental attenders can be separated almost perfectly. The relationship with other anxiety measurements, i.e. Corah's Dental Anxiety Scale and three components discernible in Weiner's Anticipation Anxiety Level Chart, was studied.

Sociodemographic correlates of dental anxiety.

In a survey comprising 620 30-40-yr-old inhabitants of a Dutch town, dental anxiety was measured along with some sociodemographic variables. The data were analyzed in an attempt to reveal associations between sociodemographically determined groups of respondents and their scores on the different measurements of dental anxiety. Women reported higher dental anxiety levels than men, with the exception of body damage anticipation anxiety. The rank order of birth seemed to have no influence. Divorced men and women reported a higher anxiety level on two of the anxiety measurements, but the association appeared to be weak. A lower level of education, irregular dental attendance, and edentulousness appeared to be associated with a higher level of dental anxiety.

Dimensionality of dental anxiety measurements.

A survey among 620, 30-40-yr-olds, was carried out in order to measure dental anxiety with Corah's DAS, Weiner's AALC, and some other questions on anxiety, among which was the duration of psychophysiologic responses prior to a dental appointment. The data were analyzed with a Non Metric Components analysis. The DAS turned out to be unidimensional. The AALC on the other hand appeared to contain four components. A second stage analysis comprising the DAS component, the four AALC components, and the remaining variables revealed a two-dimensional structure, of which only the first component is dentistry related. This component showed better differentiation of the respondents than with DAS or AALC alone. Part of AALC's questions and a question about anxiety in daily life proved to be superfluous for measuring dental anxiety. It is concluded that dental anxiety and anxiety in general have to be measured with questions covering different aspects.