Search results for "Contrast"
showing 10 items of 1162 documents
Maternal homework assistance and children's task-persistent behavior in elementary school
2018
Abstract The present study used a sample of 365 children to investigate the longitudinal associations between maternal homework assistance (i.e., help, monitoring, and autonomy granting) and children's task-persistent behavior in learning situations from grade 2 to grade 4 of elementary school. Also, the extent to which task-persistent behavior plays a role in the links between parental homework assistance and children's academic performance was examined. The results showed that the more autonomy granting mothers reported, the more task-persistent behavior children exhibited; and more task-persistent behavior children exhibited, the more autonomy their mothers granted. In contrast, the more…
Proton magnetic resonance imaging with para-hydrogen induced polarization.
2012
A major challenge in imaging is the detection of small amounts of molecules of interest. In the case of magnetic resonance imaging (MRI) their signals are typically concealed by the large background signal of e.g. the body. This problem can be tackled by hyperpolarization which increases the NMR signals up to several orders of magnitude. However, this strategy is limited for (1)H, the most widely used nucleus in NMR and MRI, because the enormous number of protons in the body screens the small amount of hyperpolarized ones. Here, we describe a method giving rise to high (1)H MRI contrast for hyperpolarized molecules against a large background signal. The contrast is based on the J-coupling i…
Digital Acquisition and Processing of Video Angiocardiograms
1986
Angiocardiographic diagnosis is still mainly based on the visual assessment of radiographic projection images recorded on photographic film. Considerable amounts of contrast material have to be selectively injected into the circulation in order to make the regions of diagnostic relevance visible in the superposition of the shadows of tissue and bone structures displayed in these transmission images. In addition, selective angiocardiography requires exact positioning of the catheter, a time-consuming procedure which is not without risk. The processing of the angiographie films obtained is difficult to maintain at a constant high quality level, and this introduces an disadvantageous delay bet…
MRI of the inner ear: use of modified GRASS and fast spin-echo sequences
1996
We report our experience with MRI of the normal and pathological inner ear with fast spin-echo and modified gradient recalled at steady state sequences. Although earlier studies on temporal bone MRI were discouraging, improvements in MR technology combined with the use of paramagnetic contrast media can make MRI a useful diagnostic tool for the assessment of inner ear pathology. Conventional spin-echo imaging seems not to be the modality of choice because of the relatively thick slices and the long acquisition times.
Segmentanatomie der Leber in der Computertomographie: Lokalisieren wir die Läsionen richtig?*
2000
Purpose: To evaluate if Couinaud's model using the planes of the major veins is an adequate tool for the presurgical localization of focal liver lesions. Methods: Biphasic helical CT scans were performed on patients evaluated for liver resection using an increased IV bolus of contrast medium (180 ml lopamidol) and 2 mm image reconstruction increments. During the first evaluation, all liver lesions were localized in the conventional way using the planes of the 3 major hepatic veins and the portal trunks as segmental boundaries. In a second review, all lesions were attributed to the nearest peripheral portal branches. The path and the segmental attribution of the portal branches were analysed…
Type 1A endoleak detachable coil embolization after endovascular aneurysm sealing: Case report
2021
Introduction Endovascular aneurysm sealing (EVAS) with the Nellix system was introduced to reduce endovascular aneurysm repair (EVAR) perioperative complications, especially endoleaks. Herein we report a case of successful type 1A endoleak managed with detachable coils embolization after EVAS. Presentation of case A 77-year-old male was referred for abdominal pain. The angio-CT scan confirmed the previous EVAS procedure and showed a type Is2 endoleak below the right renal artery resulting in a 2.5 cm aortic blister with contrast medium filling the space between the aortic wall and the endobags. The patient was considered unfit for conventional open surgery and an endovascular approach with …
Acute cerebrovascular manifestation of Takayasu arteritis
2011
International audience
Pilot Study on Visual Function and Fundus Autofluorescence Assessment in Diabetic Patients.
2015
Purpose. Evaluate optimized fundus autofluorescence (FAF) imaging in early stages of diabetic retinopathy (DR) and relate findings with conventional colour fundus imaging and visual function in diabetic patients and control subjects.Materials and Methods. FAF and colour images were obtained using the CR-2 Plus digital nonmydriatic retinal camera in seven diabetic patients and thirteen control subjects. Visual-Functioning Questionnaire-25 (VFQ-25) and Diabetes Self-Management Questionnaire (DSMQ) were used to assess the quality of life and diabetes self-care. Contrast sensitivity function (CSF) was evaluated with the Vistech 6500 chart.Results. FAF and optimized-FAF imaging showed more retin…
Computational fluid dynamics simulation to evaluate aortic coarctation gradient with contrast-enhanced CT
2014
Coarctation of aorta (CoA) is a narrowing of the aorta leading to a pressure gradient (Delta P) across the coarctation, increased afterload and reduced peripheral perfusion pressures. Indication to invasive treatment is based on values of maximal (systolic) trans-coarctation Delta P. A computational fluid dynamic (CFD) approach is herein presented for the non-invasive haemodynamic assessment of Delta P across CoA. Patient-specific CFD simulations were created from contrast-enhanced computed tomography (CT) and appropriate flow boundary conditions. Computed Delta P was validated with invasive intravascular trans-CoA pressure measurements. Haemodynamic indices, including pressure loss coeffic…
Comparison of biometric measurements using partial coherence interferometry and applanation ultrasound
2003
Abstract Purpose To compare and contrast axial length (AL) measurements assessed by ultrasound biometry and optical biometry. Setting Department of Ophthalmology, Johannes Gutenberg-University, Mainz, Germany. Methods Optical biometry and ultrasound biometry were performed in 360 eyes to measure AL. Results In eyes with a clear-appearing crystalline lens, there was a statistically significant median difference in AL measurements between the 2 methods in eyes with a normal or long length. In eyes with cataract, there was a statistically significant median difference in AL measurements in eyes with a normal or short length. In these cases, optical biometry produced larger readings than ultras…