Search results for " Enhancement"
showing 10 items of 521 documents
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…
Texture analysis of cardiac cine magnetic resonance imaging to detect nonviable segments in patients with chronic myocardial infarction.
2017
[EN] Purpose: To investigate the ability of texture analysis to differentiate between infarcted nonviable, viable, and remote segments on cardiac cine magnetic resonance imaging (MRI). Methods: This retrospective study included 50 patients suffering chronic myocardial infarction. The data were randomly split into training (30 patients) and testing (20 patients) sets. The left ventricular myocardium was segmented according to the 17-segment model in both cine and late gadolinium enhancement (LGE) MRI. Infarcted myocardium regions were identified on LGE in short-axis views. Nonviable segments were identified as those showing LGE 50%, and viable segments those showing 0 < LGE < 50% transmural …
Evaluation of demineralized bone and bone transplantsin vitroandin vivowith cone beam computed tomography imaging
2010
The objective of this study was to determine the ability of two flat panel cone beam CT (CBCT) devices to identify demineralized bone and bone transplants in vivo and in vitro.Datasets from patients with autologous bone grafts (n = 9, KaVo 3DeXam (KaVo, Biberach, Germany); n = 38, Accuitomo 40 (Morita, Osaka, Japan)) were retrospectively evaluated. Demineralized and non-demineralized porcine cancellous bone blocks were examined with the two CBCT devices. A SawBone skull (Pacific Research Laboratories, Vashon, WA) was used as a positioning tool for the bone blocks. Descriptive evaluation and image quality assessment were conducted on the KaVo 3DeXam data (voxel size 0.3 mm) using the OsiriX …
Comparison of post-activation performance enhancement (PAPE) after isometric and isotonic exercise on vertical jump performance.
2021
Purpose This study aimed to compare the post-activation performance enhancement (PAPE) induced by isometric and isotonic exercise on vertical jump performance. Methods 18 healthy trained men (25.8±2.7 years; 78.4±8.2 kg; 175.7±6.1 cm; 25.4±1.8 BMI; 126.72±10.8 kg squat 1-RM) volunteered for this study. They randomly performed two different PAPE protocols: Isotonic squats (ISOTS), which consisted of 2 sets of 3 repetitions at 75% of one-maximum repetition (1-RM); and isometric squats (ISOMS), which consisted of 2 sets of 4 seconds of submaximal (75% of 1-RM) isometric contraction at 90°-knee flexion. Countermovement jump (CMJ) height was tested at baseline and 4 minutes after each condition…
Effects of manganese injected into rat nostrils: implications for in vivo functional study of olfaction using MEMRI.
2011
WOS: 000298212500007; International audience; Manganese-enhanced magnetic resonance imaging (MEMRI) is a powerful tool for visualizing neuronal pathways and mapping brain activity modulation. A potential drawback of MEMRI lies in the toxic effects of manganese (Mn), which also depend on its administration route. The aim of this study was to analyze the effects of Mn doses injected into the nostrils of rats on both olfactory perception and MRI contrast enhancement. For this purpose, doses in the range 0-8 μmol MnCl(2) were tested. Behavioral items were quantified with and without odor stimulation during the first 2 h following Mn injection. The MRI study was performed after 16 h of intermitt…
Magnetic resonance pharmacokinetic imaging clusterization of hepatocellular carcinomas as a means to grade tumor aggressiveness.
2012
Hepatocellular carcinoma (HCC) management takes into account clinical and radiological findings, such as tumor stage, hepatic functional status and clinical symptoms. It is necessary to evaluate the number, size and location of the lesions. However, lesion aggressiveness is not considered in this therapeutic workflow, although the biology and the growth rate of the lesions have an important impact on survival. The aim of this work was to establish if the quantitative pharmacokinetic assessment of dynamic contrast-enhanced magnetic resonance images of HCC can separate lesions with different microvascular properties and biological evolution. Forty five patients with HCC and dynamic contrast-e…
Non-viral VEGF(165) gene therapy--magnetofection of acoustically active magnetic lipospheres ('magnetobubbles') increases tissue survival in an overs…
2008
Abstract Adenoviral transduction of the VEGF gene in an oversized skin flap increases flap survival and perfusion. In this study, we investigated the potential of magnetofection of magnetic lipospheres containing VEGF165-cDNA on survival and perfusion of ischemic skin flaps and evaluated the method with respect to the significance of applied magnetic field and ultrasound. We prepared perfluoropropane-filled magnetic lipospheres (‘magnetobubbles’) from Tween60-coated magnetic nanoparticles, Metafectene, soybean-oil and cDNA and studied the effect in an oversized random-pattern-flap model in the rats (n= 46). VEGF-cDNA-magnetobubbles were administered under a magnetic field with simultaneousl…
A spline-based non-linear diffeomorphism for multimodal prostate registration.
2012
This paper presents a novel method for non-rigid registration of transrectal ultrasound and magnetic resonance prostate images based on a non-linear regularized framework of point correspondences obtained from a statistical measure of shape-contexts. The segmented prostate shapes are represented by shape-contexts and the Bhattacharyya distance between the shape representations is used to find the point correspondences between the 2D fixed and moving images. The registration method involves parametric estimation of the non-linear diffeomorphism between the multimodal images and has its basis in solving a set of non-linear equations of thin-plate splines. The solution is obtained as the least…