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PURPOSE To describe and present some preliminary results for a novel algorithm for segmentation with gray-scale connectedness as a means to separate arteries and veins in magnetic resonance angiography (MRA). MATERIALS AND METHODS The proposed algorithm, SeparaSeed, uses the gray-scale degree of connectedness as a tool to find the zone surrounding each(More)
BACKGROUND Conventional magnetic resonance imaging (MRI) has relatively long scan times for routine examinations, and the signal intensity of the images is related to the specific MR scanner settings. Due to scanner imperfections and automatic optimizations, it is impossible to compare images in terms of absolute image intensity. Synthetic MRI, a method to(More)
Tortuosity of an artery can disturb fluid mechanics and cause flow separation, which might in turn promote atherogenesis. This study discusses theoretically several quantitative measures of arterial tortuosity and curvature in two dimensions and tests them with computations from digitized femoral arteriograms. When reproducibility, sensitivity to scaling(More)
The viscosity of 7 contrast media was measured using a rotational viscometer. When solutions with similar iodine concentrations were compared, the highest viscosities were found for the nonionic dimers iodixanol and iotrolan, the lowest for diatrizoate, iopamidol, and iopromide, and intermediate values for iohexol and ioxaglate. The viscosity of iohexol and(More)
For visual grading experiments, which are an easy and increasingly popular way of studying image quality, hitherto used data analysis methods are often inadequate. Visual grading analysis makes assumptions that are not statistically appropriate for ordinal data, and visual grading characteristic curves are difficult to apply in more complex experimental(More)
  • O Smedby
  • 1997
Although the distribution of atherosclerosis has been described, little is known about the direction of growth of plaques. In this study, 237 patients with slight or moderate atherosclerosis underwent femoral angiography twice at a 3-year interval, and the films were studied with computerized image analysis. First, atherosclerosis was measured as edge(More)
PURPOSE Dual Energy Computed Tomography (DECT) may provide additional information about the chemical composition of tissues compared to examination with a single X-ray energy. The aim of this in vitro study was to test whether combining two energies may significantly improve the detection of soft tissue components commonly present in arterial plaques. (More)
BACKGROUND To define and evaluate coronary contrast opacification gradients using prospectively ECG-gated single heart beat 320-detector row coronary angiography (CTA). METHODS AND RESULTS Thirty-six patients with normal coronary arteries determined by 320 x 0.5-mm detector row coronary CTA were retrospectively evaluated with customized image(More)
Despite a long tradition, conventional anatomy education based on dissection is declining. This study tested a new virtual reality (VR) technique for anatomy learning based on virtual contrast injection. The aim was to assess whether students value this new three-dimensional (3D) visualization method as a learning tool and what value they gain from its use(More)
PURPOSE To propose a technique for standardizing volume-rendering technique (VRT) protocols and to compare this with maximum intensity projection (MIP) in regard to image quality and diagnostic confidence in stenosis diagnosis with magnetic resonance angiography (MRA). MATERIAL AND METHODS Twenty patients were examined with MRA under suspicion of renal(More)