Objectives The purpose of this study was to determine if the ultrasonic integrated backscatter and echo intensity could be used in clinical diagnosis of acute myocardial infarction. Methods and Results Within 2 weeks ...Objectives The purpose of this study was to determine if the ultrasonic integrated backscatter and echo intensity could be used in clinical diagnosis of acute myocardial infarction. Methods and Results Within 2 weeks after acute myocardial infarction,35 patients underwent ultrasonic tissue characterization from the papillary short - axis view. The cyclic variation of integrated backscatter and echo intensity of three different myocardial regions perfused by left anterior descending coronary artery, left circumflex coronary and right coronary were measured . The value of cyclic variation of integrated backscatter and integrated backscatter and echo intensity≤ half of the highest value of three different myocardial regions on a same view were define as the criteria for diagnosing acute myocardial infarction , and the results were compared with coronary angiography. The sensitivity of diagnosing acute myocardial infarction by both Ultrasonic tissue characterization with integrated backscatter and echo intensity were 91. 43 % . The location of myocardial infarction detected by this tech-nique corresponded with the damaged myocardial region determined by coronary angiography. Conclusions Ultrasonic tissue characterization with integrated backscatter and echo intensity could clinically be used as a noninvasive approach in the diagnosis of acute myocardial infarction.展开更多
In this paper, we study the behavior of the solution at the crack edges for a nearly circular crack with developing cusps subject to shear loading. The problem of finding the resulting force can be written in the form...In this paper, we study the behavior of the solution at the crack edges for a nearly circular crack with developing cusps subject to shear loading. The problem of finding the resulting force can be written in the form of a hypersingular integral equation. The equation is then trans-formed into a similar equation over a circular region using conformal mapping. The equation is solved numerically for the unknown coefficients, which will later be used in finding the stress intensity factors. The sliding and tearing mode stress intensity factors are evaluated for cracks and displayed graphically. Our results seem to agree with the existing asymptotic solution.展开更多
基金This work was supported by a grant from Chongqing ScienceCommittee (1997) 22-41.
文摘Objectives The purpose of this study was to determine if the ultrasonic integrated backscatter and echo intensity could be used in clinical diagnosis of acute myocardial infarction. Methods and Results Within 2 weeks after acute myocardial infarction,35 patients underwent ultrasonic tissue characterization from the papillary short - axis view. The cyclic variation of integrated backscatter and echo intensity of three different myocardial regions perfused by left anterior descending coronary artery, left circumflex coronary and right coronary were measured . The value of cyclic variation of integrated backscatter and integrated backscatter and echo intensity≤ half of the highest value of three different myocardial regions on a same view were define as the criteria for diagnosing acute myocardial infarction , and the results were compared with coronary angiography. The sensitivity of diagnosing acute myocardial infarction by both Ultrasonic tissue characterization with integrated backscatter and echo intensity were 91. 43 % . The location of myocardial infarction detected by this tech-nique corresponded with the damaged myocardial region determined by coronary angiography. Conclusions Ultrasonic tissue characterization with integrated backscatter and echo intensity could clinically be used as a noninvasive approach in the diagnosis of acute myocardial infarction.
基金supported by the Ministry Of Higher Education Malaysia for the Fundamental Research Grant scheme,project No. 01-04-10-897FRthe NSF scholarship
文摘In this paper, we study the behavior of the solution at the crack edges for a nearly circular crack with developing cusps subject to shear loading. The problem of finding the resulting force can be written in the form of a hypersingular integral equation. The equation is then trans-formed into a similar equation over a circular region using conformal mapping. The equation is solved numerically for the unknown coefficients, which will later be used in finding the stress intensity factors. The sliding and tearing mode stress intensity factors are evaluated for cracks and displayed graphically. Our results seem to agree with the existing asymptotic solution.
