Effect of hormone therapy on carotid elasticity in postmenopausalwomen by Echo-tracking technique

Background Studies showed that arterial elasticity changes appear earlier than any structural changes, therefore, its accurate evaluation could be applied at early stage to prevent disease. Echo-tracking（E-tracking） technique can track the wall motion trajectory in real-time, calculate the change in vascular diameter automatically, and assessment of vascular stiffness and flexibility directly. This article aims to assess the change of elasticity of carotid artery after hormone therapy （HT） using Echo-tracking technology. Methods Echotracking was used to evaluate the carotid elastic moduli, such as the pressure-strain elastic modulus （Ep）, stiffness parameter （β）, arterial compliance （AC）, pulse wave conducting velocity （PWVβ） and augmentation index （AI） by Aloka α10 color Doppler ultrasound diagnosis system. Results Ep,β and PWVβ in HT group were significantly lower than those in the control group （P 〈 0.01）, while AC was obviously higher than the control group （P 〈 0.01）. E2 was negatively related to β, Ep and PWVβ （r = -0.607, r = -0.573, r = -0.574, P 〈 0.001）, while positively related to AC （r = 0.574, P 〈 0.001）; endothelial-dependent dilatation （EDD） was negatively related to β, Ep and PWVβ （r = -0.521, r = -0.411, r = -0.456, P 〈 0.001）, while positively related to AC （r = 0.443, P 〈 0.001）; But IMT was positively related to β, Ep and PWVβ（r = 0.553, r = 0.444, r = 0.529, P 〈 0.001）, while negatively related to AC （r = -0.400, P 〈 0.001）. Conclusions Arterial stiffness increases and compliance decreases in menopausal women. As EDD decreases arterial elasticity recedes, and HT can improve arterial elasticity. E-tracking technology can discover the early changes in arterial stiffness effectively and it is more sensitive in finding out the changes of stiffness in early atherosclerosis than IMT of carotid artery.

Wave Intensity Analysis of Carotid Artery:A Noninvasive Technique for Assessing Hemodynamic Changes of Hyperthyroid Patients

This study examined the wave intensity (WI) of the carotid artery in patients with hyperthyroid in order to assess the hemodynamic changes of hyperthyroid patients.A total of 86 hyperthyroid patients without cardiac morphological changes and arrhythmia, and 80 healthy control subjects were enrolled in the study.Right common carotid artery (RCCA) was selected for ultrasonic imaging to obtain WI indices, including amplitude of the peak during early systole (W1), amplitude of the peak during late systole (W2), area of the negative wave during mid-systole (NA), interval between R wave of electrocardiogram and W1 (R-1st), interval between W1 and W2 (1st-2nd).The levels of serum thyroid hormones, consisting of free triiodothyronine (FT3), free thyroxin (FT4) and thyroid stimulating hormone (TSH), were measured in hyperthyroid patients.Echocardiographic indices including left ventricular ejection fraction (LVEF) and left ventricular fraction shortening (LVFS) were determined in each subject.The results showed that the W1, W2, NA, and (1st-2nd×HR) in hyperthyroid patients were significantly higher than those in healthy controls.There was no significant difference in LVEF and LVFS between the two groups.FT3 was correlated with W1, W2, NA, (1st-2nd×HR), pulse pressure (PP) and heart rate (HR) in hyperthyroid patients.Several abnormal waves on WI curves were present in 19 hyperthyroid patients during mid-systole.It was concluded that WI technique may prove a real-time, noninvasive, sensitive and convenient tool for assessing the cardiac function and hemodynamic alterations in hyperthyroid patients.

Sea surface height measuring using InSAR altimeter

Satellite altimetry has been widely used in measuring ocean topography from space. The conventional altimeter system is the nadir radar altimeter system which has the limitations of one-dimensional measurement and is unable to get both high temporal and spatial resolution. The InSAR altimetry system using InSAR altimeter instead of nadir radar altimeter is an improvement which can get both high cross-track and along-track resolution and wide swath. However, the conventional SAR interferometry only can achieve meter level height accuracy. This paper focuses on a method of radar echo-tracking for InSAR altimeter system in order to correct the slant range measurements and finally to improve the height measurement accuracy to several centimeters＇ level. Radar slant range （from observed pixels to radar antenna） estimation error affects the height measurement accuracy badly, nevertheless not considered in the conventional SAR interferometry. The proposed method is ameliorated based on the traditional echo-model used in nadir radar altimeter system, focusing on the echo signals from observed pixels with different incident angles. Simulations of sea surface height measurements are performed in the last part of this paper, and the conclusions are drawn that, with corrected slant range, the accuracy of InSAR altimetry can be much better than the conventional SAR interferometry.