Search results for "Image Enhancement"
showing 10 items of 215 documents
Controlling diffusion of 3He by buffer gases: a structural contrast agent in lung MRI.
2006
Purpose: To study the influence of admixing inert buffer gases to laser-polarized 3 He in terms of resulting diffusion coefficients and the consequences for image contrast and resolution. Materials and Methods: The diffusion coefficient of 3 He was altered by admixing buffer gases of various molecular weights ( 4 He, N2, and SF6). The influence of the pulse sequence and the diffusion coefficient on the appearance of MRI of (laserpolarized) gases was analyzed by comparison of basic theoretical concepts with demonstrative experiments. Results: Excellent agreement between theoretical description and observed signal in simple gradient echoes was observed. A maximum signal gain can be predicted …
3D integral imaging display by smart pseudoscopic-to-orthoscopic conversion (SPOC).
2010
Previously, we reported a digital technique for formation of real, non-distorted, orthoscopic integral images by direct pickup. However the technique was constrained to the case of symmetric image capture and display systems. Here, we report a more general algorithm which allows the pseudoscopic to orthoscopic transformation with full control over the display parameters so that one can generate a set of synthetic elemental images that suits the characteristics of the Integral-Imaging monitor and permits control over the depth and size of the reconstructed 3D scene.
Dynamic laser speckle analyzed considering inhomogeneities in the biological sample
2017
Dynamic laser speckle phenomenon allows a contactless and nondestructive way to monitor biological changes that are quantified by second-order statistics applied in the images in time using a secondary matrix known as time history of the speckle pattern (THSP). To avoid being time consuming, the traditional way to build the THSP restricts the data to a line or column. Our hypothesis is that the spatial restriction of the information could compromise the results, particularly when undesirable and unexpected optical inhomogeneities occur, such as in cell culture media. It tested a spatial random approach to collect the points to form a THSP. Cells in a culture medium and in drying paint, repr…
Contrast ultrasound LI-RADS LR-5 identifies hepatocellular carcinoma in cirrhosis in a multicenter restropective study of 1,006 nodules
2018
Background & Aims The use of contrast enhanced ultrasound (CEUS) for the diagnosis of hepatocellular carcinoma (HCC) in cirrhosis was questioned because of the risk of a false positive diagnosis in cases of cholangiocarcinoma. The American College of Radiology has recently released a scheme (CEUS Liver Imaging Reporting and Data System [LI-RADS®]) to classify lesions at risk of HCC investigated by CEUS. The aim of the present study was to validate this LI-RADS scheme for the diagnosis of HCC. Methods A total of 1,006 nodules from 848 patients with chronic liver disease at risk of HCC were collected in five Italian centers and retrospectively analyzed. Nodules were classified as LR-5, (HCC) …
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…
Prevalence of coronary artery intramyocardial course in a large population of clinical patients detected by multislice computed tomography coronary a…
2008
Background: Intramyocardial course, an inborn coronary anomaly, is defined as a segment of a major epicardial coronary artery that runs intramurally through the myocardium; in particular, we distinguish myocardial bridging, in which the vessel returns to an epicardial position after the muscle bridge, and intramyocardial course, which is described as a vessel running and ending in the myocardium. Purpose: To evaluate the prevalence of myocardial bridging and intramyocardial course of coronary arteries as defined by multidetector computed tomography (MDCT) angiography. Material and Methods: The study population consisted of 242 consecutive patients (211 men, 31 women; mean age 59±6 years) w…
EEG-related Functional MRI in Benign Childhood Epilepsy with Centrotemporal Spikes
2003
The localization of epileptic foci is an important issue in children with extratemporal epilepsies. However, the value of noninvasive methods such as the EEG-assisted functional magnetic resonance imaging (fMRI) has not been sufficiently investigated in children. As a model of extratemporal epilepsies, we studied 7 patients aged 5 to 12 (median 10) years with benign childhood epilepsy and centrotemporal (rolandic) spikes. Interictal spikes were recorded during the fMRI acquisition on a MR-compatible battery-powered digital EEG system with 16 channels. The fMRI sequences were correlated off-line with the EEG spikes and analyzed with the software Statistical Parametrical Mapping SPM99. The fM…
A supervised learning framework of statistical shape and probability priors for automatic prostate segmentation in ultrasound images
2013
Prostate segmentation aids in prostate volume estimation, multi-modal image registration, and to create patient specific anatomical models for surgical planning and image guided biopsies. However, manual segmentation is time consuming and suffers from inter-and intra-observer variabilities. Low contrast images of trans rectal ultrasound and presence of imaging artifacts like speckle, micro-calcifications, and shadow regions hinder computer aided automatic or semi-automatic prostate segmentation. In this paper, we propose a prostate segmentation approach based on building multiple mean parametric models derived from principal component analysis of shape and posterior probabilities in a multi…
Evaluation of intraindividual contrast enhancement variability for determining the maximum achievable consistency in CT
2019
OBJECTIVE. The purpose of this study was to quantify temporal variability in vascular and parenchymal enhancement within the same patient and to determine technique-related factors contributing to this variability. MATERIALS AND METHODS. We identified 100 patients who underwent four CT scans within 12 months with identical acquisition and contrast injection parameters. Enhancement was recorded in the abdominal aorta, main portal vein, liver parenchyma, and subcutaneous fat. Patient demographic and body habitus data were recorded. Injection-related factors were recorded including delay time from contrast injection to image acquisition. All pairwise differences in enhancement within each pati…
Higher intracoronary attenuation improves diagnostic accuracy in MDCT coronary angiography
2006
OBJECTIVE: The purpose of this study was to investigate whether the amount of intracoronary attenuation influences the diagnostic accuracy of MDCT coronary angiography in the detection of clinically significant stenosis. MATERIALS AND METHODS: One hundred twenty patients in sinus rhythm with suspected coronary artery disease who underwent MDCT of the heart and conventional coronary angiography were retrospectively selected. The population was divided into two groups depending on median (326 H) coronary vascular enhancement (i.e., low attenuation and high attenuation). The diagnostic accuracy of MDCT for the detection of clinically significant coronary artery lesions (> or = 50% lumen reduct…