Quantitative parameters in novel spectral computed tomography: Assessment of Ki-67 expression in patients with gastric adenocarcinoma.

BACKGROUND: The level of Ki-67 expression has served as a prognostic factor in gastric cancer. The quantitative parameters based on the novel dual-layer spectral detector computed tomography (DLSDCT) in discriminating the Ki-67 expression status are unclear. AIM: To investigate the diagnostic ability of DLSDCT-derived parameters for Ki-67 expression status in gastric carcinoma (GC). METHODS: Dual-phase enhanced abdominal DLSDCT was performed preoperatively in 108 patients with gastric adenocarcinoma. Primary tumor monoenergetic CT attenuation value at 40-100 kilo electron volt (kev), the slope of the spectral curve (λHU), iodine concentration (IC), normalized IC (nIC), effective atomic number (Zeff) and normalized Zeff (nZeff) in the arterial phase (AP) and venous phase (VP) were retrospectively compared between patients with low and high Ki-67 expression in gastric adenocarcinoma. Spearman's correlation coefficient was used to analyze the association between the above parameters and Ki-67 expression status. Receiver operating characteristic (ROC) curve analysis was performed to compare the diagnostic efficacy of the statistically significant parameters between two groups. RESULTS: Thirty-seven and 71 patients were classified as having low and high Ki-67 expression, respectively. CT40 kev-VP, CT70 kev-VP, CT100 kev-VP, and Zeff-related parameters were significantly higher, but IC-related parameters were lower in the group with low Ki-67 expression status than the group with high Ki-67 expression status, and other analyzed parameters showed no statistical difference between the two groups. Spearman's correlation analysis showed that CT40 kev-VP, CT70 kev-VP, CT100 kev-VP, Zeff, and nZeff exhibited a negative correlation with Ki-67 status, whereas IC and nIC had positive correlation with Ki-67 status. The ROC analysis demonstrated that the multi-variable model of spectral parameters performed well in identifying the Ki-67 status [area under the curve (AUC) = 0.967; sensitivity 95.77%; specificity 91.89%)]. Nevertheless, the differentiating capabilities of single-variable model were moderate (AUC value 0.630 - 0.835). In addition, the nZeff VP and nICVP (AUC 0.835 and 0.805) showed better performance than CT40 kev-VP, CT70 kev-VP and CT100 kev-VP (AUC 0.630, 0.631 and 0.662) in discriminating the Ki-67 status. CONCLUSION: Quantitative spectral parameters are feasible to distinguish low and high Ki-67 expression in gastric adenocarcinoma. Zeff and IC may be useful parameters for evaluating the Ki-67 expression.

Low-Cost Metamaterial Antennas: Forward-Looking Imaging Experiment and Analysis.

A phase error correction method is proposed to compensate for the phase error in super-resolution correlated imaging based on metamaterial antennas. The varying carrier frequencies of a metamaterial antenna can generate the random radiation field for super-resolution correlation imaging, but the variation of the signal carrier frequency leads to large phase errors in the imaging results. In this proposed method, the sampling matrix in the super-resolution correlated imaging algorithm is used to compensate for the phase errors. Each element of the matrix is multiplied by a compensation phase corresponding to the phase error, and the error is subtly removed from the algorithm. In the experiment, the antenna pattern at each frequency of the metamaterial antenna is measured and recorded. In addition, an external field experiment is also carried out, and the collected data are imaged with the improved algorithm. Experimental results show that this technology can effectively solve the effect of phase errors on imaging results caused by signal carrier frequency changes.

Testosterone is associated with self-employment among Australian men.

Testosterone has pronounced effects on men's physiological development and smaller, more nuanced, impacts on their economic behavior. In this study of 1199 Australian adult males, we investigate the relationship between the self-employed and their serum testosterone levels. Because prior studies have identified that testosterone is a hormone that is responsive to external factors (e.g. competition, risk-taking), we explicitly control for omitted variable bias and reverse causality by using an instrumental variable approach. We use insulin as our primary instrument to account for endogeneity between testosterone and self-employment. This is because prior research has identified a relationship between insulin and testosterone but not between insulin and self-employment. Our results show that there is a positive association between total testosterone and self-employment. Robustness checks using bioavailable testosterone and another similar instrument (daily alcohol consumption) confirm this positive finding.

Prevalence, intensity, and prognostic significance of common symptoms in terminally ill cancer patients.

BACKGROUND: Quality of life and palliative management of end-stage cancer patients should improve with greater understanding of the prevalence, intensity, and prognostic significance of their symptoms. OBJECTIVE: We investigated the association between prevalence and intensity of common symptoms and overall survival in Chinese end-stage cancer patients. DESIGN: For this cross-sectional study, 163 Chinese patients with end-stage cancer completed an Edmonton Symptom Assessment questionnaire, and each was given a Karnofsky Performance Status (KPS) score. Overall survival was estimated via the Kaplan-Meier method. Factors affecting overall survival were determined by univariate and multivariate Cox regression analyses. RESULTS: Mean survival of these patients was 51 days. Pain, lack of appetite, and poor well-being were the most frequent symptoms, in 90.2%, 88.3%, and 87.7%, respectively. The most severe symptoms were fatigue, lack of appetite, drowsiness, and poor well-being. Fatigue, lack of appetite, drowsiness, shortness of breath, poor well-being, depression, and KPS score significantly affected overall survival rate, with a relative risk of dying of 1.560, 2.320, 1.684, 1.295, 1.912, 1.414, and 0.487, respectively (Cox regression coefficients: 0.361, 0.827, 0.539, 0.185, 0.694, 0.318, and -0.602). Fatigue, lack of appetite, shortness of breath, age, and KPS score were independent risk factors of overall survival, with a relative risk of dying of 1.581, 1.122, 1.123, 1.022, and 0.797, respectively (Cox regression coefficients: 0.458, 0.115, 0.116, 0.022, and -0.227). CONCLUSION: Fatigue, shortness of breath, lack of appetite, age, and KPS score were associated with overall survival of end-stage Chinese cancer patients.