High-resolution venography of the brain using magnetic resonance imaging

The purpose of this study was to evaluate a non-flow related magnetic resonance imaging method to visualize small veins independent of arteries in the human brain. A long TE, high-resolution 3D gradient echo MR acquisition was used to highlight venous information. The method is based on the paramagnetic property of deoxyhemoglobin and the resulting phase difference between veins and brain parenchyma at long echo times. The MR magnitude images were masked with a phase mask filter to enhance small structure visibility.. Venous information down to sub-pixel vessel diameters of several hundred microns is visible. Venous data are displayed in an angiographic manner using a minimum intensity projection algorithm. Both superficial veins and deep white matter veins are visible. The method has been successfully applied in volunteers. Preliminary results in patients with cerebral arteriovenous malformations indicate its potential in clinical applications. The proposed method is easy to implement and does not require administration of a contrast agent or application of specially designed rf pulses to highlight the veins. Rather it exploits the intrinsic magnetic properties (BOLD-effect) and the prolonged T ^_2* of venous blood. The method may be of diagnostic potential in the assessment of arteriovenous malformations or other vascular venous lesions. © 1998 Elsevier Science B.V. All rights reserved.     

IPAS: a design framework for analysis,synthesis and optimization of image processing applications for heterogenous computing architectures

Recent trends in the image processing field have led to the use of more heterogeneous hardware architectures. The reason for this increase is that specialized cores, compared to standard CPUs, offer a more efficient way of achieving image processing applications. Specialized cores have less power, resource, and area consumption. On the other hand, designing such a heterogenous system with specialized cores is a challenging, error-prone and time-consuming task. Therefore, new frameworks are necessary for bringing an image processing application onto a given target platform by means of a tool chain. Some frameworks exist, but they do not address each need of a heterogeneous image processing application. Common weaknesses are (1) the low utilization of the image processing domain, (2) the inflexibility of the programming paradigms for different hardware architectures. Therefore, we define our own domain-specific design language called IPOL. To automate the derivation and optimization process, a synthesis tool named Image Processing Architecture Synthesis was created. This tool will be the focus of this work.     

A new approach to the Noack volatility test

This paper reports on the method and preliminary results of a significant modification of the Noack volatility test. This modification permits collection and examination of the volatile products as well as of the residue. The analysis of such volatiles by chromatography and spectroscopy revealed surprising information that is especially relevant in the face of increasingly difficult automotive and heavy duty engine emission limitations. The data also showed very close agreement with the Unified Test Method for the Noack Volatility Test now covered by CEC L-40-T-87. Important to operators, the authors' modified Noack apparatus avoids the use of the toxic Wood's Metal of the earlier Noack apparatus.     

Development and validation of an algorithm for registration of serial 3D MR breast data sets

We report on the development of an algorithm to improve the registration of serial 3D MR breast images using combined global translation and rotation with locally varying parameters as geometric transformations. Several phantom and volunteer data sets were acquired and registered using mutual information as a similarity measure of the matching process. After applying a global translation by using a rigid matcher, optimum horizontal and vertical rotation angles were determined. In case of the phantom measurements, angle optimization was performed for each slice of the 3D data set of the phantom, which was deliberately shifted and rotated around different axes. In case of registration of volunteer data, optimum rotation parameters were calculated for preselected equidistant slices of the data set to speed up the calculation time. For slices located between and outside these support slices, the rotation angles were calculated by linear interpolation and extrapolation of the slope of the regression determined by the optimized angles of the support slices. The algorithm improves the registration of serial 3D MR data sets and represents a compromise between a rigid and an elastic 3D matching procedure.     

Exploring Internal Structure of Nanoporous Glasses Obtained by Leaching of Phase‐Separated Alkali Borosilicate Glasses

Mesoporous glasses – the leaching products of phase‐separated alkali borosilicate glasses – are widely used in fundamental research and practical applications. In this work, the option to control their internal mesopore structure by varying the conditions of microphase separation has been studied. Structure and transport characterization of a family of nanoporous glasses obtained under different conditions has been performed using a combination of several experimental techniques, including gas adsorption, nuclear magnetic resonance cryoporometry and diffusometry.     

Restoration and reconstruction from overlapping images formulti-image fusion

This paper describes a technique for restoring and reconstructing a scene from overlapping images. In situations where there are multiple, overlapping images of the same scene, it may be desirable to create a single image that most closely approximates the scene, based on the data in all of the available images. For example, successive swaths acquired by NASA's moderate imaging spectrometer (MODIS) will overlap, particularly at wide scan angles, creating a severe visual artifact in the output image. Resampling the overlapping swaths to produce a more accurate image on a uniform grid requires restoration and reconstruction. The one-pass restoration and reconstruction technique developed in this paper yields mean-square optimal resampling, based on a comprehensive end-to-end system model that accounts for image overlap and is subject to user-defined and data-availability constraints on the spatial support of the filter     

In vivo studies of an implantable energy convertor for skeletal muscle powered cardiac assist

A device that harnesses the mechanical energy of skeletal muscle contracting in a linear configuration has been implanted in goats. This energy convertor transforms muscle work to hydraulic energy that could drive a variety of cardiac assist devices. The device is mounted with a rib clamp and plate affixed to the sternum by cortical bone screws. A transcutaneous hydraulic line carries a silicon based working fluid to an external system that controls the muscle load. In 60 to 70 kg goats, the latissimus dorsi insertion was reattached to the energy convertor. A Telectronics myostimulator with intramuscular electrodes stimulated the latissimus dorsi. In acute implants, hydraulic pressures in excess of 150 psi were obtained. Chronic implantation of the device allowed system evaluation in the conscious unanesthetized animal. Two weeks after implant, hydraulic pressures in excess of 200 psi were obtained and energy transferred to the external loading system exceeded 1 J per contraction. Six weeks after implant, the device continued to cycle freely. These initial results are very promising and suggest an implantable energy convertor is feasible. Development of an energy convertor is an important step toward tether-free skeletal muscle powered cardiac assist devices.