Objectives: To compare the image quality, accuracy and effective dose of the default diagnostic pro-gram with the low dose program. Methods: The diagnostic and low dose programs of three-dimen-sional rotational angiog...Objectives: To compare the image quality, accuracy and effective dose of the default diagnostic pro-gram with the low dose program. Methods: The diagnostic and low dose programs of three-dimen-sional rotational angiography were compared considering their signal to noise ratio, their carrier to noise ratio and their actual radiation dose in μGy⋅m<sup>2</sup>/kg. An anthropomorphic phantom underwent both types of scans to evaluate the effective dose. Comparative measurements of vessel diameters were taken in the diagnostic and the low dose program and compared to the angiography as exact basis. The image quality of the scans using the different programs was rated by a specialist physician. Results: The low dose scan does use significantly less radiation and still provides images, which are adequate for 3D navigation of catheter-based interventions. Conclusion: Three-dimensional rotational angiography can be applied with the low dose program and is sufficient for 3D navigation.展开更多
Colorectal cancer(CRC)is the third most diagnosed form of cancer and second most deadly cancer worldwide.Introduction of better screening has improved both incidence and mortality.However,as the coronavirus disease 20...Colorectal cancer(CRC)is the third most diagnosed form of cancer and second most deadly cancer worldwide.Introduction of better screening has improved both incidence and mortality.However,as the coronavirus disease 2019(COVID-19)pandemic began,healthcare resources were shunted away from cancer screening services resulting in a sharp decrease in CRC screening and a backlog of patients awaiting screening tests.This may have significant effects on CRC cancer mortality,as delayed screening may lead to advanced cancer at diagnosis.Strategies to overcome COVID-19 related disruption include utilizing stool-based cancer tests,developing screening protocols based on individual risk factors,expanding telehealth,and increasing open access colonoscopies.In this review,we will summarize the effects of COVID-19 on CRC screening,the potential longoutcomes,and ways to adapt CRC screening during this global pandemic.展开更多
The concept of cointegration describes an equilibrium relationship among a set of time-varying variables, and the cointegrated relationship can be represented through an error-correction model (ECM). The error-correct...The concept of cointegration describes an equilibrium relationship among a set of time-varying variables, and the cointegrated relationship can be represented through an error-correction model (ECM). The error-correction variable, which represents the short-run discrepancy from the equilibrium state in a cointegrated system, plays an important role in the ECM. It is natural to ask how the error-correction mechanism works, or equivalently, how the short-run discrepancy affects the development of the cointegrated system? This paper examines the effect or local influence on the error-correction variable in an error-correction model. Following the argument of the second-order approach to local influence suggested by reference [5], we develop a diagnostic statistic to examine the local influence on the estimation of the parameter associated with the error-correction variable in an ECM. An empirical example is presented to illustrate the application of the proposed diagnostic. We find that the short-run discre pancy may have strong influence on the estimation of the parameter associated with the error-correction model. It is the error-correction variable that the short-run discrepancies can be incorporated through the error-correction mechanism.展开更多
文摘Objectives: To compare the image quality, accuracy and effective dose of the default diagnostic pro-gram with the low dose program. Methods: The diagnostic and low dose programs of three-dimen-sional rotational angiography were compared considering their signal to noise ratio, their carrier to noise ratio and their actual radiation dose in μGy⋅m<sup>2</sup>/kg. An anthropomorphic phantom underwent both types of scans to evaluate the effective dose. Comparative measurements of vessel diameters were taken in the diagnostic and the low dose program and compared to the angiography as exact basis. The image quality of the scans using the different programs was rated by a specialist physician. Results: The low dose scan does use significantly less radiation and still provides images, which are adequate for 3D navigation of catheter-based interventions. Conclusion: Three-dimensional rotational angiography can be applied with the low dose program and is sufficient for 3D navigation.
文摘Colorectal cancer(CRC)is the third most diagnosed form of cancer and second most deadly cancer worldwide.Introduction of better screening has improved both incidence and mortality.However,as the coronavirus disease 2019(COVID-19)pandemic began,healthcare resources were shunted away from cancer screening services resulting in a sharp decrease in CRC screening and a backlog of patients awaiting screening tests.This may have significant effects on CRC cancer mortality,as delayed screening may lead to advanced cancer at diagnosis.Strategies to overcome COVID-19 related disruption include utilizing stool-based cancer tests,developing screening protocols based on individual risk factors,expanding telehealth,and increasing open access colonoscopies.In this review,we will summarize the effects of COVID-19 on CRC screening,the potential longoutcomes,and ways to adapt CRC screening during this global pandemic.
基金This project was supported by the National Natural Science Foundation (No. 79800012 and No. 79400014).
文摘The concept of cointegration describes an equilibrium relationship among a set of time-varying variables, and the cointegrated relationship can be represented through an error-correction model (ECM). The error-correction variable, which represents the short-run discrepancy from the equilibrium state in a cointegrated system, plays an important role in the ECM. It is natural to ask how the error-correction mechanism works, or equivalently, how the short-run discrepancy affects the development of the cointegrated system? This paper examines the effect or local influence on the error-correction variable in an error-correction model. Following the argument of the second-order approach to local influence suggested by reference [5], we develop a diagnostic statistic to examine the local influence on the estimation of the parameter associated with the error-correction variable in an ECM. An empirical example is presented to illustrate the application of the proposed diagnostic. We find that the short-run discre pancy may have strong influence on the estimation of the parameter associated with the error-correction model. It is the error-correction variable that the short-run discrepancies can be incorporated through the error-correction mechanism.
