Search results for "contrast"
showing 10 items of 1162 documents
Effect of 3rd-order aberrations on human vision
2007
To investigate the effect of 3rd-order aberrations on human vision.Grupo de Ciencias de la Visión, University of Murcia, Murcia, Spain.The 3rd-order aberrations coma and trefoil were induced with purpose-designed soft contact lenses, 3 inducing coma (low [0.05 microm], medium [0.13 microm], high [1.03 microm]) and 3 inducing trefoil (low [0.07 microm], medium [0.17 microm], high [0.96 microm]). Monocular high-contrast (HCVA) and low-contrast (LCVA) visual acuities and contrast sensitivity were measured in 11 subjects wearing contact lenses with a 5.0 mm artificial pupil.The reduction in HCVA and LCVA was statistically significant only for the highest coma and trefoil values (P.0001). For co…
Long-term follow-up of a multifocal apodized diffractive intraocular lens after cataract surgery.
2007
Purpose To report the long-term performance of the AcrySof ReSTOR SA60D3 intraocular lens (IOL) after cataract surgery. Setting University Hospital Maastricht, Maastricht, The Netherlands. Methods This prospective clinical trial comprised 44 eyes (22 consecutive patients) having cataract surgery with implantation of the ReSTOR IOL. Monocular and binocular uncorrected distance visual acuity, best corrected distance visual acuity, uncorrected near visual acuity, best distance-corrected near visual acuity, spectacle dependence, undesired visual symptoms, patient satisfaction, and incidence of posterior capsule opacification were analyzed 6 months and 3 years postoperatively. Results The mean u…
Contrast-enhanced second-harmonic sonography in the detection of pseudocapsule in renal cell carcinoma.
2004
“OBJECTIVE. Our purpose was to assess the capacity of contrast-enhanced second-harmonic sonography to detect a pseudocapsule in renal masses compared with conventional gray-scale sonography. SUBJECTS AND METHODS. Thirty-two patients with 40 renal masses suspicious for renal cancer (mean diameter, 3.1 cm) were prospectively studied with contrast-enhanced second-harmonic sonography during IV administration of a second-generation sonographic contrast agent. The sonographic criteria for the presence of a pseudocapsule were a peritumoral hypoanechoic halo on conventional gray-scale imaging and a rim of perilesional enhancement, increasing in the tardive phase of the examination, on contrast-enha…
Motor imagery training: Kinesthetic imagery strategy and inferior parietal fMRI activation
2017
Motor imagery (MI) is the mental simulation of action frequently used by professionals in different fields. However, with respect to performance, well‐controlled functional imaging studies on MI training are sparse. We investigated changes in fMRI representation going along with performance changes of a finger sequence (error and velocity) after MI training in 48 healthy young volunteers. Before training, we tested the vividness of kinesthetic and visual imagery. During tests, participants were instructed to move or to imagine moving the fingers of the right hand in a specific order. During MI training, participants repeatedly imagined the sequence for 15 min. Imaging analysis was performed…
Forty-slice MDCT enteroclysis: evaluation after oral administration of isotonic solution in Crohn's disease.
2007
Objective. The aim of this study was to evaluate the accuracy of multidetector computed tomography (MDCT) enteroclysis after oral hyperhydration with isotonic solution in detecting bowel wall alterations in patients with Crohn’s disease. Materials and methods. Twenty-eight patients with a diagnosis of Crohn’s disease established by ileocolonoscopy and histology were enrolled in the study; 15 patients with negative ileocolonoscopy served as controls. In all cases, MDCT enteroclysis was performed after oral administration of 2,000 ml of isotonic solution and intravenous administration of N-butylscopolamine. Axial, isotropic multiplanar and volume-rendered reconstructions were used to evaluate…
Transcatheter embolization of a renal artery pseudoaneurysm after open partial nephrectomy.
2011
Twelve days after an open partial nephrectomy, a 31-year-old man was re-admitted urgently for acute lumbar pain. An emergent helical computed tomography scan with intravenous contrast revealed a 3-cm renal artery pseudoaneurysm at the site of the partial nephrectomy, which was responsible for a large perirenal hematoma. Transarterial hyperselective embolization successfully occluded the pseudoaneurysm with less than 1 mL of N-butyl-2-cyanoacrylate, an embolizing agent less costly than coils. The kidney parenchyma was fully preserved.
Crohn's disease: A comparative prospective study of transabdominal ultrasonography, small intestine contrast ultrasonography, and small bowel enema
2005
Background: Small intestine contrast ultrasonography (SICUS), when performed after distention of the small bowel lumen with an iso-osmolar polyethylene glycol electrolyte-balanced solution, shows high sensitivity (100%) and specificity (97%) in detecting small bowel abnormalities in patients who have not received a diagnosis but in whom there is a suspicion of intestinal diseases. The diagnostic yield of SICUS remains to be established in detecting small bowel lesions in patients with proven Crohn's disease (CD) in comparison with transabdominal ultrasonography (TUS), and in relationship to the experience of the operator, using small bowel enema (SBE) as the “gold standard.” Aim: The aim of…
Passive exposure to speech sounds modifies change detection brain responses in adults
2019
In early life auditory discrimination ability can be enhanced by passive sound exposure. In contrast, in adulthood passive exposure seems to be insufficient to promote discrimination ability, but this has been tested only with a single short exposure session in humans. We tested whether passive exposure to unfamiliar auditory stimuli can result in enhanced cortical discrimination ability and change detection in adult humans, and whether the possible learning effect generalizes to different stimuli. To address these issues, we exposed adult Finnish participants to Chinese lexical tones passively for 2 h per day on 4 consecutive days. Behavioral responses and the brain's event-related potenti…
Synergy of spatial frequency and orientation bandwidth in texture segregation
2021
Defining target textures by increased bandwidths in spatial frequency and orientation, we observed strong cue combination effects in a combined texture figure detection and discrimination task. Performance for double-cue targets was better than predicted by independent processing of either cue and even better than predicted from linear cue integration. Application of a texture-processing model revealed that the oversummative cue combination effect is captured by calculating a low-level summary statistic (\(\Delta CE_m\)), which describes the differential contrast energy to target and reference textures, from multiple scales and orientations, and integrating this statistic across channels wi…
Influence of myocardial fibrosis and blood oxygenation on heart T2* values in thalassemia patients
2009
Purpose To determine whether T2* measurements quantifying myocardial iron overload in thalassemia patients are influenced by myocardial fibrosis and blood oxygenation. Materials and Methods Multislice multiecho T2* was performed in 94 thalassemia patients in order to quantify myocardial iron overload. The left ventricle was automatically segmented into a 16-segment standardized heart model, and the T2* value on each segment as well as the global T2* were calculated. Delayed enhanced cardiovascular magnetic resonance (DE-CMR) images were obtained to detect myocardial fibrosis. The blood oxygenation was assessed by the noninvasive measurement of partial pressure of oxygen (pO2). Results Myoca…