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Ultrasound Technique (ultrasound + technique)
Selected AbstractsEffects of C-peptide on forearm blood flow and brachial artery dilatation in patients with type 1 diabetes mellitusACTA PHYSIOLOGICA, Issue 3 2001E. Fernqvist-Forbes Recent studies suggest that C-peptide increases blood flow in both exercising and resting forearm in patients with type 1 diabetes. Now we have studied the effect of C-peptide administration on endothelial-mediated and non-endothelial-mediated arterial responses as well as central haemodynamics in 10 patients with type 1 diabetes in a placebo-controlled double-blind study. Euglycaemia was maintained with an i.v. insulin infusion before and during the study. A high-resolution ultrasound technique and Doppler echocardiography were used to assess haemodynamic functions. Brachial artery blood flow and brachial artery diameter were measured in the basal state, 1 and 10 min after reactive hyperaemia and 4 min after sublingual glyceryl trinitrate administration (GTN; endothelial-independent vasodilatation), both before and after the end of 60-min C-peptide (6 pmol kg,1 min,1) or saline infusion periods. Echocardiographic measurements were also performed before and at the end of the infusion periods. Seven healthy age-matched males served as controls for vascular studies. The patients showed a blunted brachial dilatation after reactive hyperaemia in comparison with the healthy controls (2.1 ± 0.5% vs. 9.3 ± 0.3%, P < 0.001), indicating a disturbed endothelial function. C-peptide infusion compared with saline resulted in increased basal blood flow (33 ± 6%, P < 0.001) and brachial arterial dilatation (4 ± 1%, P < 0.05). Left ventricular ejection fraction seemed to be improved (5 ± 2%, P < 0.05) at the end of C-peptide infusion compared with placebo. The vascular response to reactive hyperaemia and GTN was not affected by C-peptide infusion. Our results demonstrate that physiological concentrations of C-peptide increase resting forearm blood flow, brachial artery diameter and left ventricular systolic function in patients with type 1 diabetes. [source] Metastable zone determination of lipid systems: Ultrasound velocity versus optical back-reflectance measurementsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 5 2010Kesarin Chaleepa Abstract The metastable zone width (MZW) of a multi-component system as influenced by the process parameters cooling rate, agitation speed, and additive concentration was determined via ultrasound velocity measurements. The results were compared with those obtained by optical back-reflectance measurements (ORM) using coconut oil as a model substance. Increasing the cooling rate led to the shift of the nucleation point to lower temperatures. This tendency was better visualized by the ultrasonic curves while a significant disturbance of the ORM signal could be observed. Agitation led to an increase of the nucleation temperature and hence a narrower metastable zone. The influence of an additive on the MZW was found to strongly depend on its concentration. The MZW detected by the ultrasound technique was narrower compared to that obtained by the ORM method, indicating the faster response to the phase transition of the ultrasound technique. Another advantage of the ultrasound technique was the in situ evaluation of the experimental data, while ORM needed a linear fitting to estimate the saturation temperature. Furthermore, ultrasound velocity measurements are based on density determination of the medium whereas the ORM sensor is able to detect only particles that are located within the measuring zone and possess a well-defined size. Practical applications: MZW is one of the most important parameters that determine the characteristics of crystalline products. However, a proper technique that can be used in MZW detection in fat systems has rarely been reported, due to the difficulties in dealing with natural fats. The findings of this study can greatly help those who are involved in the field of fat crystallization from both the academic and the practical point of view. This is due to the fact that new and promising techniques for the online and in situ determination of the MZW of fats, with high accuracy, and reproducibility, under most process conditions, were clarified in this work. The readers can easily follow the procedure developed in this paper. Also information about the influence of process parameters and additives on the MZW is included. [source] New method of dynamic color doppler signal quantification in metastatic lymph nodes compared to direct polarographic measurements of tissue oxygenationINTERNATIONAL JOURNAL OF CANCER, Issue 6 2005Thomas Scholbach Abstract Tumor growth depends on sufficient blood and oxygen supply. Hypoxia stimulates neovascularization and is a known cause for radio- and chemoresistance. The objective of this study was to investigate the use of a novel ultrasound technique for the dynamic assessment of vascularization and oxygenation in metastatic lymph nodes. Twenty-four patients (age 44,78 years) with cervical lymph node metastases of squamous cell head and neck cancer were investigated by color duplex sonography and 17 (age 46,78 years) were investigated additionally with polarography. Sonography was performed after contrast enhancer infusion under defined conditions. Intranodal perfusion data (color hue, colored area) were measured automatically by a novel software technique. This allows an evaluation of blood flow dynamics by calculating perfusion intensity,velocity, perfused area, as well as the novel parameters tissue resistance index (TRI) and tissue pulsatility index (TPI),for each point of a complete heart cycle. Tumor tissue pO2 was measured by means of polarographic needle electrodes placed intranodally. The sonographic and polarographic data were correlated using Pearson's test. Sonography demonstrated a statistically significant inverse correlation between hypoxia and perfusion and significant TPI and TRI changes with different N-stages. The percentage of nodal fraction with less than 10 mmHg oxygen saturation was significantly inversely correlated with lymph node perfusion (r = ,0.551; p = 0.021). Nodes with a perfusion of less than 0.05 cm/sec flow velocity showed significantly larger hypoxic areas (p = 0.006). Significant differences of TPI and TRI existed between nodes in stage N1 and N2/N3 (p = 0.028 and 0.048, respectively). This new method of dynamic signal quantification allows a noninvasive and quantitative assessment of tumor and metastatic lymph node perfusion by means of commonly available ultrasound equipment. © 2004 Wiley-Liss, Inc. [source] A Noncontact Ultrasound Approach for Mechanical Property Determination of CheesesJOURNAL OF FOOD SCIENCE, Issue 7 2003B.-K. Cho ABSTRACT: Noncontact ultrasound parameters, such as velocity and attenuation coefficient, were directly measured using air instability compensation transducers and correlated with Young's modulus, hardness, and toughness of different types of cheeses. Ultrasound velocity was highly correlated with the mechanical properties of cheeses whereas no significant relationship between the ultrasound energy attenuation coefficient and the mechanical properties were shown. The noncontact ultrasound technique demonstrated excellent performance for thickness measurement of cheeses with an accuracy of 99.98% (standard error = 0.089 mm). Results indicated that noncontact air instability compensation ultrasound technique has a good potential for nondestructive and accurate measurement of ultrasound parameters, thickness, and mechanical properties of food materials. [source] Harmonic Imaging in Acute Stroke: Detection of a Cerebral Perfusion Deficit With Ultrasound and Perfusion MRIJOURNAL OF NEUROIMAGING, Issue 2 2003Karsten Meyer MD ABSTRACT Perfusion harmonic imaging of the brain is a new ultrasound technique for assessing cerebral perfusion. In a patient with acute middle cerebral artery infarction, this method detected a cerebral perfusion deficit corresponding to the area of delayed perfusion as displayed by perfusion magnetic resonance imaging. [source] An outcome study on complications using routine ultrasound assistance for internal jugular vein cannulationACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2007M. Lamperti Background:, Ultrasound guidance for central venous cannulation is advised by recent guidelines, but is not being applied in everyday practice. The purpose of this study was to determine the reduction in complications when applying an ultrasound locating device for internal jugular vein catheterization. Methods:, An observational study was conducted from November 2004 to October 2005 in a tertiary neurosurgical hospital on 300 patients undergoing internal jugular vein cannulation using an ultrasound technique. Patients were not randomized and operators were trained using theoretical and practical courses. Prior to the study, the investigators, who were consultant anaesthesiologists, had to perform at least 20 successful supervised cannulations. Results:, Cannulation was successful in all cases. The incidence of arterial puncture was 2.7%, and multiple venous punctures represented the main minor complication (14%). Bivariate analysis of the overall complications revealed no significant correlation with age group, American Society of Anesthesiologists' (ASA) classification, body mass index, or position and diameter of the vein. Conclusions:, Ultrasound cannulation of the internal jugular vein minimized complications. These could be avoided when new ultrasound probes and specific needles are introduced. [source] Real-Time Contrast Imaging: A New Method to Monitor Capillary Recruitment in Human Forearm Skeletal MuscleMICROCIRCULATION, Issue 3 2008Alexandra H. Mulder ABSTRACT Objective: Muscle capillary perfusion can be measured by contrast-enhanced ultrasound. We examined whether a less time-consuming ultrasound technique, called "real-time imaging," could be used to measure capillary recruitment in human forearm skeletal muscle. Methods: We measured microvascular blood volume and microvascular flow velocity using bolus injections of contrast microbubbles after forearm muscle exercise and a two-hour infusion of insulin into the brachial artery (both associated with capillary recruitment) and after sodium nitroprusside infusion (no changes in flow distribution). Results: After an intravenous bolus injection of the contrast agent, the steady-state concentration of contrast agent in forearm muscle lasted long enough (approximately 190 seconds) for the duration of the measurements (which take 70,80 seconds), rendering the continuous infusion of microbubbles unnecessary. Microvascular blood-volume measurements showed a good short-time reproducibility and a good reproducibility after repositioning of the forearm. Reproducibility of microvascular flow velocity was too low. Exercise and insulin infusion both increased microvascular blood volume, consistent with capillary recruitment. Sodium nitroprusside had no effect. Conclusion: Real-time contrast imaging, after bolus injections of an ultrasound contrast agent, provides reliable information about capillary recruitment in human forearm skeletal muscle, and may offer a valuable tool in studying human (patho)physiology. [source] Combined Vitamin C and E Supplementation Retards Early Progression of Arteriosclerosis in Heart Transplant PatientsNUTRITION REVIEWS, Issue 11 2002Article first published online: 16 SEP 200 The development of arteriosclerosis is the limiting factor for the long-term survival and the major cause of mortality in patients with heart transplants. Various factors, including oxidative stress, contribute to the progression of the disease. In a recent clinical trial using the intravascular ultrasound technique, which detects the early stages of disease development, supplementation with vitamins C and E retarded the progression of coronary arteriosclerosis during the early stage following cardiac transplantation. [source] Prenatal diagnosis of congenital epulis by three-dimensional ultrasound and magnetic resonance imagingPRENATAL DIAGNOSIS, Issue 2 2006Sun-Kwon Kim Abstract Congenital epulis is a benign intraoral tumor that has rarely been diagnosed prenatally. We report a fetus with congenital epulis diagnosed by three-dimensional (3-D) ultrasound and fetal magnetic resonance imaging (MRI) at 35 weeks' gestation. We show an image of congenital epulis using a new ultrasound technique, the 3-D multislice view, which shows images similar to CT or MRI. This is a short case report of congenital epulis diagnosed prenatally by 3-D ultrasound using multislice view and MRI. Copyright © 2006 John Wiley & Sons, Ltd. [source] Obese children show increased intimal wall thickness and decreased pulse wave velocityCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 5 2008Frida Dangardt Summary Objective:, Childhood obesity confers an increased risk of vascular changes and adult cardiovascular disease. Using a high-resolution ultrasound technique that enables separation of intimal and medial layers, we examined the intimal thickness (IT) and intimal,medial thickness (IMT) of radial (RA) and dorsal pedal (DPA) arteries and the pulse wave velocity (PWV) in overweight/obese children and adolescents and in healthy subjects. Methods and results:, IT and IMT of RA and DPA and PWV were measured in 33 obese children and adolescents (13·9 ± 1·6 years) and in 18 matched lean controls (14·3 ± 2·2). Increased RA IT was found in the obese group, whereas no differences in RA IMT or medial thickness were observed. Obese females accounted for the entire difference in RA IT (P = 0·04). DPA IT was inversely correlated with HDL cholesterol in the obese group (,0·56, P = 0·0089). PWV was lower in the obese group than in the lean group (6·2 ± 0·8 versus 7·0 ± 0·9 m s,1, respectively; P = 0·001). Conclusions:, Obese children and adolescents, primarily females, present with increased RA IT. The decreased PWV in the obese versus lean subjects might reflect general vasodilatation. [source] | |||||||||||||