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Methodologies of deriving phase information from pulsatile intracranial pressure (ICP) signal and characterizing its phase coordination with electrocardiogram (ECG) signal were discussed. The application of ICP phase characterization methods to data from several clinical contexts showed that 1) Unstable periods of ICP were associated with a decreased ICP phase coordination with ECG; 2) Surgical treatment...
The extravascular matrix is believed to carry negative charge due to its glycosaminoglycans (GAGs) composition. In the present study, we developed an electrodiffusion-convection model to investigate the mechanisms by which this negative charge affects the charged molecule transport through the interstitial space. The model predictions demonstrate that the apparent tissue diffusion coefficient of negatively...
High-intensity focused ultrasound (HIFU) has become a viable alternative for treatment of primary and metastatic liver tumors. We evaluated the effects of presence of a large blood vessel and its distance to the tumor on lesion size during HIFU heating. A finite element method (FEM) was used to obtain the temperature distribution for a transfer equation based on large blood vessels convection effect...
We have developed a computer-aided diagnosis system (CAD) to detect abnormalities in fundus images. In Japan, ophthalmologists usually detect hypertensive changes by identifying arteriolar narrowing and focal arteriolar narrowing. The purpose of this study is to develop an automated method for detecting arteriolar narrowing and focal arteriolar narrowing on fundus images. The blood vessel candidates...
We applied the concept of "phase synchronization" from nonlinear dynamics to the complex relationship between intracranial pressure (ICP) and arterial blood pressure (ABP) signals. This method is based on multiresolution wavelet transform (MRWT) in which the signals are divided into different frequency bands. We examined ICP and ABP signals from anaesthetized dogs, exploring normal ICP and...
Current implantable LVADs are bulky and expensive. They all require high-risk surgery for insertion including a need for a heart/lung machine and complex connection to the heart or major blood vessels. This paper presents a newly designed "plug and play" transventricle LVAD that can be plugged into the circulation easily and work instantly with no complicated surgical procedure, no prime,...
For accurate predictions of the tissue temperature distribution during cryosurgery a thermal model should incorporate the individual impact of large blood vessels. In presence of large vessel, configuring cryoprobe becomes very important because misplacement of cryoprobes may result in either inadequate cooling temperatures in the target tissue due to the heating nature of large vessels or undesired...
Micro/nano-particle drug delivery systems are being developed for improving therapeutic effects. However, most studies can only evaluate the delivery properties by indirectly measuring the pharmacokinetic changes of the drugs. It had been difficult to directly assay the drug carrier status and distribution in vivo. We described here a method using intravital microscopy to visualize individual drug...
Wave propagation through the arterial system changes with age and disease state, and mutant mice are often used to study these conditions. We have developed several noninvasive ultrasonic techniques to measure blood velocity and vessel wall motion from which we can calculate aortic pulse wave velocity (PWV), local compliance, impedance spectra, characteristic impedance (Zc), augmentation index (AI),...
Hemodynamic stresses are known to degenerate the arterial wall and be involved in the pathogenesis of intracranial aneurysm formation and development. The present study simulates the formation and growth of aneurysms by focusing on the interplay between the wall shear stress, degeneration of the mechanical wall properties, and the wall deformation. We construct numerical aneurysm models arisen from...
Hemodynamics is widely believed to correlate with the stenosis of coronary artery bypass graft (CABG). Although some researchers had investigated distal anastomosis, further studies upon the proximal anastomosis are still necessary as the initiation and growth of the stenosis process may be influenced by the nature of the flow at the proximal anastomosis. Therefore in this project, flow characteristics...
Idealized geometries of bypass grafts have been constructed to analyze the blood flow in an aorto-coronary bypass graft system. In this paper we discuss the influence of the realistic bypass graft geometry for the in-plane and out-of-plane aorto-left bypass graft models on the wall shear stress distribution. In the in-plane aorto-left coronary bypass graft model we have the centerlines of the aorta,...
Studies suggest that obstructive sleep apnea syndrome (OSAS) is causally related to abnormal cardiovascular autonomic control in adults, but this has not been established in pediatric OSAS. The goal of this study was to quantify autonomic system dysfunction, as manifested by cardiovascular response abnormalities, in children with OSAS. During wakefulness, we continuously measured the ECG, arterial...
The present study tested the hypothesis that the role of ERK in phasic and tonic contractile responses is declined by hindlimb unloading (HU) in rat femoral arteries. Male Wistar rats were randomised into HU and control group (n=7). After 14d, the femoral arteries were isolated and cut into 3-mm ring segments. In the absence or presence of PD98059(MEK inhibitor), contractile response to NE(10muM)...
Empirical mode decomposition (EMD) is a recently introduced tool for decomposing signals into so-called intrinsic mode functions (IMF). These IMF represent the data by means of oscillating waves with local zero mean. In some sense the decomposition can be compared with a time-varying filter bank, i.e., signals are decomposed using band limited filters with band widths that vary in time. The main attribute...
The automated extraction of brain vessels from magnetic resonance angiography (MRA) has found its applications in vascular disease diagnosis, endovascular operation and neurosurgical planning. In this paper we first present a concise technical review on cerebral vasculature extraction from MRA. It reveals the latest development in the area of vessel extraction. Then we detail the main challenges to...
The ways of angiography are divided into two kinds at present: the invasive type and the non invasive type. Because the magnetic resonance angiography (MRA) has advantages of the non invasive type, thus people can accept MRA more easily. Presently, to diagnoses for the initial stage triage of the blood vessel on clinic by MRA mostly. We to be allowed to see clearly that the shape of lower limb artery...
Ultrasound-induced blood stasis has been observed for more than thirty years. Most of the literature has been focused on the health risks associated with this phenomenon and methods employed to prevent stasis from occurring during ultrasound imaging. To date, experimental observations have been either in vitro or invasive. The current work demonstrates ultrasound-induced blood stasis in murine tumor...
This paper presents a new technique for identification of regional dysfunctions in the left ventricle from 2-D echocardiography. It uses a novel left ventricular border tracking algorithm based on fuzzy inference system. In this paper we show how the regional dysfunction present in the left ventricle can be identified by tracking the movement of centre of mass of left ventricle in a 2D space. The...
This paper describes a method to extract the vascular centerlines and contours in coronary angiography. The proposed approach associates geometric moments for the estimation of a "cylinder-like model" and relies on a tracking process. The orientation of the cylinder axis and its local diameter are computed from the analytical expressions of the geometric moments of up to order 2. Experimental...
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