			Home About us Contact

Clear Visualization (clear + visualization)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Direct Visualization of Deformation in Volumes

COMPUTER GRAPHICS FORUM, Issue 3 2009
Stef Busking
Abstract Deformation is a topic of interest in many disciplines. In particular in medical research, deformations of surfaces and even entire volumetric structures are of interest. Clear visualization of such deformations can lead to important insight into growth processes and progression of disease. We present new techniques for direct focus+context visualization of deformation fields representing transformations between pairs of volumetric datasets. Typically, such fields are computed by performing a non-rigid registration between two data volumes. Our visualization is based on direct volume rendering and uses the GPU to compute and interactively visualize features of these deformation fields in real-time. We integrate visualization of the deformation field with visualization of the scalar volume affected by the deformations. Furthermore, we present a novel use of texturing in volume rendered visualizations to show additional properties of the vector field on surfaces in the volume. [source]

Clinical evaluation of aortic diseases using nonenhanced MRA with ECG-triggered 3D half-Fourier FSE

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2001
Joji Urata MD
Abstract The efficacy of the nonenhanced magnetic resonance angiography (MRA) technique known as fresh-blood imaging (FBI), using electrocardiograph (ECG)-triggered 3D half-Fourier fast spin-echo (FSE), was evaluated for the detection and characterization of aortic diseases. Seventy-five consecutive patients with aortic disease underwent the FBI examination on a 1.5-T clinical imager. The results showed that the FBI technique permits clear visualization of aortic diseases, and the vessel branches and their relationship, which provides valuable information. Therefore, the nonenhanced FBI technique is appropriate to use for screening purposes. J. Magn. Reson. Imaging 2001;14:113,120. © 2001 Wiley-Liss, Inc. [source]

Pulsed Z-spectroscopic imaging of cross-relaxation parameters in tissues for human MRI: Theory and clinical applications

MAGNETIC RESONANCE IN MEDICINE, Issue 5 2002
Vasily L. Yarnykh
Abstract A new method of pulsed Z-spectroscopic imaging is proposed for in vivo visualization and quantification of the parameters describing cross-relaxation between protons with liquid-like and solid-like relaxation properties in tissues. The method is based on analysis of the magnetization transfer (MT) effect as a function of the offset frequency and amplitude of a pulsed off- resonance saturation incorporated in a spoiled gradient-echo MRI pulse sequence. The theoretical concept of the method relies on an approximated analytical model of pulsed MT that provides a simple three-parameter equation for a pulsed steady-state Z-spectrum taken far from resonance. Using this model, the parametric images of cross-relaxation rate constant, content, and T2 of the semisolid proton fraction can be reconstructed from a series of MT-weighted images and a coregistered T1 map. The method was implemented on a 0.5 T clinical MRI scanner, and it provided high-quality 3D parametric maps within an acceptable scanning time. The estimates of cross-relaxation parameters in brain tissues were shown to be quantitatively consistent with the literature data. Clinical examples of the parametric images of human brain pathologies (multiple sclerosis and glioma) demonstrated high tissue contrast and clear visualization of the lesions. Magn Reson Med 47:929,939, 2002. © 2002 Wiley-Liss, Inc. [source]

Gadobenate dimeglumine as a contrast agent for MRI of the mouse liver

NMR IN BIOMEDICINE, Issue 8 2007
Yusuke Inoue
Abstract We investigated the characteristics and utility of gadobenate dimeglumine (Gd-BOPTA) for MRI of the mouse liver. Mice were imaged under isoflurane anesthesia using a T1 -weighted, three-dimensional fast low-angle shot (3D FLASH) sequence before and after intravenous or subcutaneous injection of Gd-BOPTA, and the time course of the contrast effect was examined. The appropriate dose for subcutaneous injection was determined visually, and the inter- and intra-observer reproducibilities in liver volumetry were evaluated with and without contrast injection. When mice were imaged sequentially before and after Gd-BOPTA injection and isoflurane anesthesia was maintained throughout the experiment, a long-lasting contrast effect was noted in the liver. Subcutaneous injection caused delayed, but favorable, enhancement. Washout from the liver was definitely accelerated in conscious mice in comparison with anesthetized mice. Visual evaluation indicated that a dose of 0.1,mmol/kg was appropriate for clear delineation of the entire liver margin, and the application of Gd-BOPTA significantly improved the inter- and intra-observer reproducibilities of liver volumetry. In conclusion, the intravenous or subcutaneous injection of Gd-BOPTA has a favorable contrast effect for the mouse liver, resulting in clear visualization of the liver border and improved reproducibility of liver volumetry. The possible influence of anesthesia on the pharmacokinetics of a contrast agent should be considered in determining the optimal scan timing. Copyright © 2007 John Wiley & Sons, Ltd. [source]