Search results for "ULTRASOUND"
showing 10 items of 1259 documents
Analysis of discrete and continuous distributions of ventilatory time constants from dynamic computed tomography.
2005
In this study, an algorithm was developed to measure the distribution of pulmonary time constants (TCs) from dynamic computed tomography (CT) data sets during a sudden airway pressure step up. Simulations with synthetic data were performed to test the methodology as well as the influence of experimental noise. Furthermore the algorithm was applied to in vivo data. In five pigs sudden changes in airway pressure were imposed during dynamic CT acquisition in healthy lungs and in a saline lavage ARDS model. The fractional gas content in the imaged slice (FGC) was calculated by density measurements for each CT image. Temporal variations of the FGC were analysed assuming a model with a continuous…
MR-guided focused ultrasound application for moving target tumor ablation in abdominal area: Coil selection
2020
PubMed: 32276552
Architecture in cortical bone and ultrasound transmission velocity
1993
The square of ultrasound transmission velocity in a material is correlated to the modulus of elasticity, which is an indicator of its mechanical properties. This might make the measurement of ultrasound transmission velocity useful in the noninvasive diagnosis of bone diseases. Bone, however, is not an isotropic material but is architecturally structured. The aim of our study was to investigate and especially to quantify the influence of architecture in cortical bone on ultrasound transmission velocity. Twenty-two rectangular, flat specimens of cortical bone were prepared from diaphysis of fresh pig radius. Ultrasound transmission velocity was measured parallel and perpendicular to directio…
Reversible effect of MR and ELF magnetic fields (0.5 T and 0.5 mT) on human lymphocyte activation patterns.
2006
Purpose: The aim of this study was to investigate the effects of magnetic fields (MF) of different intensity generated by a magnetic resonance (MR) unit (0.5 Tesla) and a double cylindrical coil (0.5 mTesla) on human CD4+ T cell lines. Materials and methods: CD4+ T cells were exposed for two hours under isothermal conditions (37 ± 0.5°C) to the above mentioned MF; a control group was provided for each exposed sample. After exposure, the samples were analysed in the laboratory for the following endpoints: Release of cytokines, expression of surface markers, cell proliferation and levels of cytosolic free-calcium. Results: Exposure to MF for 2 h and subsequent in vitro stimulation in the pres…
The role of MR imaging in the assessment of renal allograft vasculature.
2018
Renal allograft dysfunction after transplantation is a relatively common occurrence with various potential etiologies. Vascular etiologies are of particular importance as early surgical or minimally invasive intervention can, in some cases, salvage the graft. Diagnosis of vascular pathology resulting in allograft dysfunction requires a thorough workup, of which imaging is a key component. Generally, ultrasound is the first-line imaging modality. More recently, MRI has been shown to be an effective and safe modality for diagnosis of vascular pathology after renal transplantation, particularly for diagnosis of transplant renal artery stenosis. This review will summarize imaging modalities tha…
Determination of consensus kQ values for megavoltage photon beams for the update of IAEA TRS-398
2020
The IAEA is currently coordinating a multi-year project to update the TRS-398 Code of Practice for the dosimetry of external beam radiotherapy based on standards of absorbed dose to water. One major aspect of the project is the determination of new beam quality correction factors, kQ, for megavoltage photon beams consistent with developments in radiotherapy dosimetry and technology since the publication of TRS-398 in 2000. Specifically, all values must be based on, or consistent with, the key data of ICRU Report 90. Data sets obtained from Monte Carlo (MC) calculations by advanced users and measurements at primary standards laboratories have been compiled for 23 cylindrical ionization chamb…
Bioresorbable vascular scaffold use for coronary bifurcation lesions: A substudy from GHOST EU registry
2016
Objectives The aim of this study was to evaluate midterm outcomes of bioresorbable vascular scaffolds (BVS) implanted in bifurcation lesions. Background BVS have emerged as an alternative to conventional metallic drug-eluting stents for the treatment of coronary complex lesions. Methods Between November 2011 and January 2014, 1189 patients underwent percutaneous coronary intervention with BVS at 10 European centers (GHOST EU registry). Of these, 289 consecutive patients (302 bifurcation lesions) treated with either single-stenting (n = 260) or double-stenting (n = 42) were evaluated. Results True bifurcations were treated in 44.7%. Intravascular ultrasound and optical coherence tomography w…
Ultrasound assisted reductive cleavage of eudesmane and guaiane γ-enonelactones. Synthesis of 1α,7α,10αH-guaian-4,11-dien-3-one and hydrocolorenone f…
2001
Abstract Ultrasound enhances the rate of reductive cleavage of the C6–oxygen bond of sesquiterpene enonelactones. trans-Eudesmanolides 1c–1g, cis-eudesmanolides 2a–2c, and trans-guaianolides 4a–4d react with Zn in acetic acid–H2O under sonochemical conditions to afford the corresponding sesquiterpene acids 3a–3g and 5a–5d, respectively in good yields. Starting from 5d two natural guaianes 1α,7α,10αH-guaian-4,11-dien-3-one (6) and hydrocolorenone (7) have been prepared in good yields through a straightforward sequence.
ChemInform Abstract: Ultrasound-Assisted Reductive Cleavage of Eudesmane and Guaiane γ-Enonelactones. Synthesis of 1α,7α,10αH-Guaian-4,11-dien-3-one …
2010
Abstract Ultrasound enhances the rate of reductive cleavage of the C6–oxygen bond of sesquiterpene enonelactones. trans-Eudesmanolides 1c–1g, cis-eudesmanolides 2a–2c, and trans-guaianolides 4a–4d react with Zn in acetic acid–H2O under sonochemical conditions to afford the corresponding sesquiterpene acids 3a–3g and 5a–5d, respectively in good yields. Starting from 5d two natural guaianes 1α,7α,10αH-guaian-4,11-dien-3-one (6) and hydrocolorenone (7) have been prepared in good yields through a straightforward sequence.
ChemInform Abstract: Ultrasound-Assisted Reductive Cleavage of Sesquiterpene γ- Enonelactones.
2010
Abstract Ultrasound enhances the rate of reductive cleavage of the C 6 -oxygen bond of several cis - and trans - sesquiterpene γ-enonelactones. Interestingly ultrasound overrides the stereoelectronic requirements for the reductive cleavage of the most usually occurring sesquiterpene trans -lactones.