Search results for "contrast"
showing 10 items of 1162 documents
ATLAS OF CONTRAST-ENHANCED SONOGRAPHY OF FOCAL LIVER LESIONS
2015
This book offers an image-based, comprehensive quick reference guide that will assist in the interpretation of contrast-enhanced ultrasound (CEUS) examinations of the liver in daily practice. It describes and depicts typical and atypical behavior of both common and less frequently observed focal liver lesions. For each type of lesion, the findings on pre- and post-contrast images are presented and key characteristics are highlighted. Individual chapters also focus on the assessment of response to locoregional and systemic treatment and the impact of European guidelines on CEUS. The Atlas of Contrast-Enhanced Sonography of Focal Liver Lesions will serve as an invaluable hands-on tool for pra…
Cognitive predictors of single-digit and procedural calculation skills and their covariation with reading skill.
2006
Abstract This study examined the extent to which children’s cognitive abilities in kindergarten and their mothers’ education predict their single-digit and procedural calculation skills and the covariance of these with reading skill in Grade 4. In kindergarten, we assessed children’s (N = 178) basic number skills, linguistic skills, and visual attention. In Grade 4, we assessed their calculation and reading skills. Data on children’s cognitive ability at 5 years of age and their mothers’ level of education were also collected. The results showed that both of the core components of calculation, single-digit and procedural calculation, as well as their covariance with reading, were predicted …
Do Parents’ Causal Attributions Predict the Accuracy and Bias in their Children’s Self‐Concept of Maths Ability? A longitudinal study
2007
The present study investigated the extent to which parents’ causal attributions predict the accuracy of, and bias in, their children’s self‐concept of maths ability. Participants were 207 children and their 182 mothers and 167 fathers, who were assessed during the children’s first and second primary school years. The results showed that the more parents thought that their children succeeded because of ability, the more accurate the children’s self‐concept of maths ability became. In contrast, the more the parents attributed their children’s success to effort, the less accurate and more optimistic the children’s self‐concept of ability became.
Gadolinium-chelating nanogels as MR contrast agesnts specifically targeting tumor cells
2014
Development of multifunctional nanogels coordinating paramagnetic ions and displacing targeting ligands for preferential accumulation into tumors. Low molecular-weight Gd-chelates are widely used in clinical MRI for various purposes. However, these contrast agents (CAs) have several shortcomings: they rapidly extravasate from blood vessels to the interstitial space, have a short circulation times and show poor contrast at high magnetic fields. Incorporating gadolinium into flexible nanogels has the potential of increasing intravascular half-life, accumulation and retention in specific body compartments of the CA as well as increasing the MR signal, since many metal ions can be coordinated t…
MRI of the pulmonary parenchyma.
1999
Imaging of the pulmonary parenchyma represents a unique challenge for MRI. Limited signal is caused by low proton density, susceptibility artifacts, and physiological motion (cardiac pulsation, respiration). Recently, further improvements in MRI techniques have widened the potential for investigations of pulmonary parenchymal disease. These include very short echo times, ultrafast turbo-spin-echo acquisitions, projection reconstruction technique, breathhold imaging, ECG triggering, contrast agents (perfusion imaging, aerosols), sodium imaging, hyperpolarized noble gas imaging, and oxygen enhancement. By using widely available techniques, MRI is helpful in the assessment of (a) acute alveoli…
Helium-3 imaging of pulmonary ventilation.
1998
In the first studies in humans, the 3He gas was Helium is an inert, non-radioactive, noble gas. directly inhaled from the glass cell or via a mouth 3He is a rare isotope with a nuclear spin c. As it tip or plastic bag [2, 3]. The estimated inhaled is derived from tritium decay, it is quite expensive. volume in our studies was 400–500 ml. Recently, Non-polarized 3He costs 100–150 US$. Advanwe developed a computer-assisted application tages for applications in humans are: negligible system which is compatible with spontaneous solubility in water or blood, no adverse effects — breathing, assisted or mechanical ventilation. The widely used in deep-sea diving (80% He, 20% lungs can be flushed wi…
Contrast-enhanced MRI of the lung
2000
The lung has long been neglected by MR imaging. This is due to unique intrinsic difficulties: (1) signal loss due to cardiac pulsation and respiration; (2) susceptibility artifacts caused by multiple air-tissue interfaces; (3) low proton density. There are many MR strategies to overcome these problems. They consist of breath-hold imaging, respiratory and cardiac gating procedures, use of short repetition and echo times, increase of the relaxivity of existing spins by administration of intravenous contrast agents, and enrichment of spin density by hyperpolarized noble gases or oxygen. Improvements in scanner performance and frequent use of contrast media have increased the interest in MR ima…
Hyperpolarized 3helium gas as a novel contrast agent for functional MRI of ventilation.
2002
The use of inhaled hyperpolarized 3He gas in MRI is a recent approach for ventilation imaging. It has recently received enormous interest since it is capable of producing new and regional information on normal and abnormal lung ventilation. Promising preclinical and preliminary clinical results are the driving force to start phase II trials with patients suffering from obstructive and restrictive lung diseases.
Dynamic19F-MRI of pulmonary ventilation using sulfur hexafluoride (SF6) gas
2001
A new method for dynamic imaging of pulmonary wash-in and wash-out kinetics of inhaled sulfur hexafluoride (SF6) gas was developed. Measurements at the fluorine-19 Larmor frequency were performed in pigs using a gradient echo pulse sequence with 0.5 ms echo time and a measurement time of 9.1 s per image. Dynamic MRI was performed during wash-in and wash-out of SF6 gas in mechanically ventilated porcine lungs. A postprocessing strategy was developed for quantitative determination of wash-out time constants in the presence of noise. Mean wash-out constants were 4.78 ± 0.48 breaths vs. 4.33 ± 0.76 breaths for left and right lung when ventilation was performed with low tidal volume, and 1.73 ± …
Kontrastmittelverstärkte 3D-MR-Perfusion der Lunge: Einsatz paralleler Bildgebungstechniken bei gesunden Probanden
2004
PURPOSE Evaluation of lung perfusion by contrast-enhanced 3D MRI using partial parallel imaging techniques. MATERIALS AND METHODS Eight healthy volunteers were examined using a contrast-enhanced dynamic FLASH 3D sequence with partial parallel imaging technique at 1.5 T MRI with a TA of 1.5 sec. The whole lung was covered by 36 coronal slices. A ventral, middle and dorsal slice of each lung was manually segmented and signal-to-time curves were computed. For absolute quantification of blood flow through the right and left pulmonary artery, phase-contrast flow measurements were performed. RESULTS No significant difference was found between the signal intensity in the right (8.9 +/- 2.6) and le…