Computed tomography perfusion(CTP)plays a crucial role in guiding reperfusion therapy and patient selection for acute ischemic stroke(AIS)through perfusion parameter maps of the brain;however,its widespread use is lim...Computed tomography perfusion(CTP)plays a crucial role in guiding reperfusion therapy and patient selection for acute ischemic stroke(AIS)through perfusion parameter maps of the brain;however,its widespread use is limited by the complexity of acquisition protocols and high radiation dose.Previous studies have attempted to reduce radiation exposure by equally lowering the temporal sampling rate;however,it may miss the peak of arterial enhancement,leading to underestimation of blood flow parameter.Here,we investigate the feasibility of using a generative adversarial network(GAN)to generate perfusion maps from 3 phases of CTP(mCTP).The three phases were chosen based on the multiphase computed tomography angiography scanning protocol:the peak arterial input function phase,the peak venous output function phase,and the delayed venous output function phase.The findings demonstrate that the GAN model achieved high visual overlap and performance for cerebral blood flow and time-to-maximum maps,with a mean structural similarity index measure of 0.921 to 0.971 and 0.817 to 0.883,a mean normalized root mean squared error of 0.019 to 0.108 and 0.058 to 0.064,and a mean learned perceptual image patch similarity of 0.039 to 0.088 and 0.141 to 0.146,respectively.For the 2 external datasets,the volume agreement between the model-and CTP-derived infarct and hypoperfusion areas was the intraclass correlation coefficient of 0.731 to 0.883 and 0.499 to 0.635,and the Spearman correlation coefficient of 0.720 to 0.808 and 0.533 to 0.6540,respectively.Qualitative assessments of diagnostic quality further confirmed that the mCTP-derived maps were comparable to those obtained from traditional CTP.In conclusion,the GAN-based model is effective in generating perfusion maps from mCTP,which could serve as a viable alternative to traditional CTP in the diagnostic evaluation of AIS.展开更多
The new rationalα-polynomials are used to solve the Falkner-Skan equation.These polynomials are equipped with an auxiliary parameter.The approximated solution to the Falkner-Skan equation is obtained by the new ratio...The new rationalα-polynomials are used to solve the Falkner-Skan equation.These polynomials are equipped with an auxiliary parameter.The approximated solution to the Falkner-Skan equation is obtained by the new rational a-polynomials with unknown coefficients.To find the unknown coefficients and the auxiliary parameter contained in the polynomials,the collocation method with Chebyshev-Gauss points is used.The numerical examples show the efficiency of this method.展开更多
QOS (Quality of Service) parameter definitions are the basis of further QOS control.But QOS parameters defined by orgallizations such as ISO and ITU are incoherent and incompatible. It leads to the inefficiency of QOS...QOS (Quality of Service) parameter definitions are the basis of further QOS control.But QOS parameters defined by orgallizations such as ISO and ITU are incoherent and incompatible. It leads to the inefficiency of QOS controls. Based on the analysis of QOS parameters defined by ISO and ITU, this paper first promotes Minimum QOS Parameter Set in transport layer. It demonstrates that the parameters defined by ISO and ITU can be represented by parameters or a combination of parameters of the Set. The paper also expounds that the Set is open and manageable and it can be the potential unified base for QOS parameters.展开更多
基金supported in part by the National Key R&D Program of China under Grants 2024YFA1012002 and 2024YFC2417804the National Natural Science Foundation of China under Grants U21A6005 and 12226004.
文摘Computed tomography perfusion(CTP)plays a crucial role in guiding reperfusion therapy and patient selection for acute ischemic stroke(AIS)through perfusion parameter maps of the brain;however,its widespread use is limited by the complexity of acquisition protocols and high radiation dose.Previous studies have attempted to reduce radiation exposure by equally lowering the temporal sampling rate;however,it may miss the peak of arterial enhancement,leading to underestimation of blood flow parameter.Here,we investigate the feasibility of using a generative adversarial network(GAN)to generate perfusion maps from 3 phases of CTP(mCTP).The three phases were chosen based on the multiphase computed tomography angiography scanning protocol:the peak arterial input function phase,the peak venous output function phase,and the delayed venous output function phase.The findings demonstrate that the GAN model achieved high visual overlap and performance for cerebral blood flow and time-to-maximum maps,with a mean structural similarity index measure of 0.921 to 0.971 and 0.817 to 0.883,a mean normalized root mean squared error of 0.019 to 0.108 and 0.058 to 0.064,and a mean learned perceptual image patch similarity of 0.039 to 0.088 and 0.141 to 0.146,respectively.For the 2 external datasets,the volume agreement between the model-and CTP-derived infarct and hypoperfusion areas was the intraclass correlation coefficient of 0.731 to 0.883 and 0.499 to 0.635,and the Spearman correlation coefficient of 0.720 to 0.808 and 0.533 to 0.6540,respectively.Qualitative assessments of diagnostic quality further confirmed that the mCTP-derived maps were comparable to those obtained from traditional CTP.In conclusion,the GAN-based model is effective in generating perfusion maps from mCTP,which could serve as a viable alternative to traditional CTP in the diagnostic evaluation of AIS.
文摘The new rationalα-polynomials are used to solve the Falkner-Skan equation.These polynomials are equipped with an auxiliary parameter.The approximated solution to the Falkner-Skan equation is obtained by the new rational a-polynomials with unknown coefficients.To find the unknown coefficients and the auxiliary parameter contained in the polynomials,the collocation method with Chebyshev-Gauss points is used.The numerical examples show the efficiency of this method.
文摘QOS (Quality of Service) parameter definitions are the basis of further QOS control.But QOS parameters defined by orgallizations such as ISO and ITU are incoherent and incompatible. It leads to the inefficiency of QOS controls. Based on the analysis of QOS parameters defined by ISO and ITU, this paper first promotes Minimum QOS Parameter Set in transport layer. It demonstrates that the parameters defined by ISO and ITU can be represented by parameters or a combination of parameters of the Set. The paper also expounds that the Set is open and manageable and it can be the potential unified base for QOS parameters.
