Search results for "Contrast"
showing 10 items of 1162 documents
ADC measurements in diffuse large B-cell lymphoma and follicular lymphoma: a DWI and cellularity study.
2012
Diffusion-weighted magnetic resonance imaging (DW-MRI) allows quantifying the random motion of water molecules in tissue by means of apparent diffusion coefficient (ADC) measurements. The aim of the study was to determine whether ADC measurements allow discrimination of diffuse large B-cell lymphoma (DLBCL) from follicular lymphoma (FL), and to examine the relationship between cellularity and ADC value of the tumor using DWI.Thirty-two patients with histologically proven non-Hodgkin lymphoma (21 with DLBCL and 11 with FL, 17 males and 15 females, mean age 62±13 years) underwent conventional MRI and DWI examination before treatment. The ADC values of DLBCL were compared to those of FL. The A…
Contrast-Enhanced Ultrasonography With SonoVue
2009
Objective. We investigated the ability of contrast-enhanced ultrasonography with SonoVue (Bracco SpA, Milan, Italy), a sulfur hexafluoride microbubble contrast agent, to reveal differences between benign and malignant focal splenic lesions. Methods. In a prospective study we investigated 35 lesions in 35 patients (24 male and 11 female; mean age ± SD, 54 ± 15 years) with focal splenic lesions detected by B-mode ultrasonography. After intravenous injection of 1.2 to 2.4 mL of SonoVue, the spleen was examined continuously for 3 minutes using low–mechanical index ultrasonography with contrastspecific software. The final diagnosis was established by histologic examination, computed tomography, …
Crystalens HD Intraocular Lens Analysis Using an Adaptive Optics Visual Simulator
2013
PURPOSE To compare visual and optical quality of the Crystalens HD intraocular lens (IOL) with that of a monofocal IOL. METHODS The wavefront aberration patterns of the monocular Akreos Adapt AO IOL and the single-optic accommodating Crystalens HD IOL were measured in a model eye. The Crystalens IOL was measured in its nonaccommodative state and then, after flexing the haptic to produce 1.4 mm of movement, in its accommodative state. Using an adaptive optics system, subjects' aberrations were removed and replaced with those of pseudophakes viewing with either lens. Monocular distance visual acuity (DVA) at high (100%), medium (50%), and low (10%) contrast and contrast sensitivity (CS) were …
Hemodynamic Effects of Nonionic Contrast Bolus Injection and Oxygen Inhalation During Pulmonary Angiography in Patients With Chronic Major-Vessel Thr…
1996
Background Pulmonary angiography is the gold standard for the diagnosis of chronic thromboembolic pulmonary hypertension; however, major complications have been reported. This study evaluates the hemodynamic effects of direct pulmonary nonionic contrast bolus injection and oxygen inhalation in patients with chronic thromboembolic pulmonary hypertension. Methods and Results In 33 patients, hemodynamic parameters were measured after oxygen inhalation and during bolus injection of nonionic contrast medium in a control group (group 1, n=11), in a group of patients with moderately severe pulmonary hypertension (group 2, n=9), and in a group with severe pulmonary hypertension (group 3, n=13). Ox…
Tumori gastrointestinali stromali: Aspetti con tomografia computerizzata multidetettore (40-strati)
2006
Purpose. The purpose of this study was to describe the findings and evaluate the role of multidetector (40-slice) computed tomography (MDCT) in the preoperative assessment of gastrointestinal stromal tumours (GISTs). Materials and methods. Thirteen patients with histologically proven GIST (size: 4-30 cm; mean: 9 cm) underwent 40-slice MDCT after the ingestion of 1,000 ml of water. Images were obtained before and 70 s after intravenous injection of 120 ml of iodinated contrast agent. Two experienced radiologists reviewed the CT findings to evaluate lesion site, size, margins, attenuation, growth pattern, enhancement pattern, ascites, lymphadenopathy, direct invasion to adjacent organs and di…
TC perfusionale nell'ischemia cerebrale acuta: Valore predittivo dei parametri di perfusione cerebrale nel discriminare il tessuto vitale da quello i…
2007
Purpose. The aim of this study was to assess the value of computed tomography (CT) perfusion parameters in differentiating tissue viability in acute stoke patients. Materials and methods. Thirteen patients (mean age 63.3 years) with nonhaemorrhagic stroke underwent multidetector perfusion CT within 3 h of symptom onset. Images were continuously acquired at the basal ganglia over 40 s during injection of 90 ml of iodinated contrast medium injected at a rate of 9 ml/s with a 9-s delay. Z-axis coverage was 20 mm. All patients underwent diffusion-weighted magnetic resonance imaging (DWI) within 12 h of perfusion CT to define the extent of the infarct. Perfusion CT data were analysed in regions …
Mesopic contrast sensitivity function after excimer laser photorefractive keratectomy.
2002
ABSTRACT PURPOSE: To evaluate contrast sensitivity under mesopic conditions in patients who had undergone uncomplicated excimer laser photorefractive keratectomy (PRK) for myopia. METHODS: Monocular contrast sensitivity function was measured with the Stereo Optical ?A.C.T. chart in 26 patients who had received PRK using the Nidek EC-5000 excimer laser system. Mean preoperative refractive error was -6.23 ? 1.69 D (range, -4.00 to -8.25 D); postoperatively, mean refractive error was -0.36 ? 0.58 D (range, -0.75 to +0.50 D). Contrast sensitivity function was measured 6 months after surgery using four different chart luminances: 85, 5.0, 2.5, and 0.1 cd/m2, the first being a photopic level and …
Mesopic Contrast Sensitivity Function After Laser in situ Keratomileusis
2003
ABSTRACT PURPOSE: To evaluate contrast sensitivity under mesopic conditions in patients who have undergone uncomplicated bilateral laser in situ keratomileusis (LASIK) for myopia. METHODS: Best-corrected monocular contrast sensitivity was measured with the Stereo Optical F.A.C.T. chart at 1.5, 3, 6, 12, and 18 c/deg in 20 patients (20 left eyes) before and after bilateral LASIK (with the Nidek EC-5000 excimer laser and the Automated Corneal Shaper). Mean preoperative refractive error was -6.40 ± 1.28 D (range -4.00 to -8.00 D) and postoperative mean refractive error was -0.41 ± 0.45 D (range -0.75 to +0.50 D). Contrast sensitivity function was measured before and 6 months after surgery usin…
Soleus aponeurosis strain distribution following chronic unloading in humans: an in vivo MR phase-contrast study.
2006
The in vivo strain properties of human skeletal muscle-tendon complexes are poorly understood, particularly following chronic periods of reduced load bearing. We studied eight healthy volunteers who underwent 4 wk of unilateral lower limb suspension (ULLS) to induce chronic unloading. Before and after the ULLS, maximum isometric ankle plantar flexion torque was determined by using a magnetic resonance (MR)-compatible dynamometry. Volumes of the triceps surae muscles and strain distribution of the soleus aponeurosis and the Achilles tendon at a constant submaximal plantar flexion (20% pre-maximal voluntary contraction) were measured by using MRI and velocity-encoded, phase-contrast MRI techn…
Psychophysiological and vocal measures in the detection of guilty knowledge.
2004
The Guilty Knowledge Test (GKT) and its variant, the Guilty Actions Test (GAT), are both psychophysiological questioning techniques aiming to detect guilty knowledge of suspects or witnesses in criminal and forensic cases. Using a GAT, this study examined the validity of various physiological and vocal measures for the identification of guilty and innocent participants in a mock crime paradigm. Electrodermal, respiratory, and cardiovascular measures successfully differentiated between the two groups. A logistic regression model based on these variables achieved hit rates of above 90%. In contrast to these results, the vocal measures provided by the computerized voice stress analysis system …