The porous, guidewire-directed, detachable aneurysm liner: a new concept in the endovascular treatment of intracranial aneurysms.

A new device for the endovascular treatment of aneurysms is described. It consists of a guidewire-directed porous liner or bag, detachably mounted on a microcatheter and designed to be inserted into an aneurysm and to be filled with detachable coils or other embolic agents. Several prototypes have been made. Preliminary in vitro and in vivo experiments have demonstrated its behavior in relatively wide-necked aneurysms.

Comparison of fluence rate distributions made by side-firing fibers in an optical phantom.

Side-firing fibers are used to provide coagulative therapy to the urologic tract. These fibers use different optical technologies to deflect the beam transverse to the fibers' optical axis. This produces emitted beams which differ in both beam direction and divergence angles. The relative optical performance of 13 fibers was studied in an optical phantom suspension. The fluence rate distribution created by each side-firing fiber was determined. The fluence rate distribution accounts for both the direct and spurious beams emitted from side-firing fibers as well as the light scattering produced by the target tissue. Based upon limited clinical dosimetry studies, the relative fluence rate distribution appears to indicate general exposure conditions for the evaluated fibers. © 1999 Society of Photo-Optical Instrumentation Engineers.

Induction of lambda prophage near the site of focused UV laser radiation.

DNA damage from photon scatter or beam spread during UV excimer laser irradiation was investigated using the induction of bacteriophage lambda in E. coli BR339. Prophage induction in these cells leads to the production of beta-galactosidase which can be detected colorimetrically by the application of appropriate substrates. An agar surface overlayed with BR339 cells was placed at various distances from the focal point of a converging lens and exposed to either 193 or 248 nm laser radiation. Energy densities ranging from approximately 5 mJ/cm2 to 30 J/cm2 were used. Ablation with 193 nm laser radiation produced an 800 microns wide clear 'trench' surrounded by a 500 microns zone of cells in which lambda had been induced. Following ablation with 248 nm laser radiation, the zone of induction was several millimeters wide. Exposures to 193 nm radiation at 170 mJ/cm2/pulse produced visible ablation of the agar surface at 1.7 J/cm2. Lambda induction was observed surrounding cleared ablation areas. The presence of induction in this system suggests that both 248 and 193 nm excimer laser radiation delivered at high energy densities has sufficient spread or scatter to damage DNA in cells surrounding areas of ablation.

Determining x-ray projections for coil treatments of intracranial aneurysms.

The endovascular coil embolization of intracranial saccular aneurysms requires a set of specific X-ray images with which to view the aneurysm during coiling. These two-dimensional (2-D) images, known as working projections, should be optimal for measuring the aneurysm sac diameter, inserting the first coil, and checking coil overhang into the surrounding vessels. At present the gantry tilt that produces these images is found by the radiologist by trial and error. In this paper, we present a method for automatically finding the angles that will produce the desired X-ray projections. Our method consists of four steps: 1) finding the location and orientation of the aneurysm neck; (2) labeling the aneurysm sac; 3) determining the optimal tilts for viewing the aneurysm during coiling; and 4) adjusting the optimal tilts for change in the patient orientation between pre-Guglielmi detachable coil (GDC) scanning and the coiling treatment. We discuss these steps and present results of the algorithm applied to pathological examples in the form of simulated X-ray images. A final discussion is given for one example where our results have been applied in a clinical situation.

An accurate laser radiometer for determining visible exposure times.

A laser light radiometer has been developed for the Electro-Optics Branch of the Center for Devices and Radiological Health (CDRH). The radiometer measures direct laser radiation emitted in the visible spectrum. Based upon this measurement, the instrument's microprocessor automatically determines at what time duration the exposure to the measured laser radiation would exceed either the class I accessible emission limits of the Federal Performance Standard for laser products or the maximum permissible exposure limits of laser user safety standards. The instrument also features automatic background level compensation, pulse measurement capability, and self-diagnosis. Measurement of forward surface illumination levels preceding HpD photoradiation therapy is possible.

The ultrasonic evaluation of psoas abscess (tropical pyomyositis) in children.

Psoas abscesses in children are not rare in tropical and sub-tropical countries and are related to staphylococcus aureus infection and poor socio-economic conditions. The condition should be considered in all children with the triad of pyrexia, flank pain and hip symptoms. Ultrasound is a readily available and definitive examination. Sonography was used in a series of 45 patients. The findings are discussed and two representative cases presented.

In vitro production of viable bacteriophage in carbon dioxide and argon laser plumes.

Both CO2 and argon laser ablation of an agar substrate containing high titres of bacteriophage phi X174 create plumes which disperse viable phage particles. Irradiances at the beam impact site ranged from 73 to 215 W/cm2 for the CO2 laser and from 40 to 227 W/cm2 for the argon laser. To increase the absorption of argon laser radiation, oxidized hemoglobin was added to the target material. Plume-borne viable phage were observed to be associated with particles large enough to settle out from the plume within 100 mm of the beam impact site. The ratio of the number of dispersed viable phage to the number of viable phage potentially dispersible by a single, 1-second laser exposure was on the order of 10(-6) to 10(-5).

Comparison of the thermal tissue effects produced by aged sapphire and silica hemispherical tips.

This study evaluated the performance of sapphire and fused silica hemispherical tips under the same exposure conditions. Lesions produced in the chicken breast and a blood field were sectioned for light and transmission polarizing microscopy. Lesion size and thermal damage area were recorded as a function of the tips accumulated exposure. The tips transmission was measured after every 1,000 J of exposure. Fused silica tips lasted for approximately 5,000 J and experienced significant surface and transmission deterioration. The sapphire hemispherical tips lasted for > 12,000 J with no surface and transmission deterioration. Lesions produced with the fused silica tips generally increased in depth with use, and depths of 6 mm were common. Lesions produced by the sapphire tips were subsurface spherical areas of coagulation with the tissue surface relatively intact. This difference in resulting lesions may be attributed to the higher thermal conductivity of sapphire.

Effect of coolant flow on the performance of round sapphire tips in a saline field.

Round sapphire and silica tips have been studied as surgical probes for focusing Nd:YAG laser radiation during various surgical indications. Since most of these data have been obtained with silica tips from Surgical Laser Technology, there are limited data on the physical performance of round sapphire tips. An investigation of round sapphire tip performance during tissue ablation was undertaken. Nd:YAG laser power was delivered in repetitive 2-sec exposures to a round sapphire tip placed on fresh skinned chicken breast. Total exposures of 1,000 J were performed at different saline perfusion rates. The tip's performance in terms of tissue perforation rate, blanched tissue area, tissue heating rate, and forward transmission was measured. Best tip performance occurred at the lowest cooling rates and was independent of the tip's forward transmission value. No physical deterioration of the tip's optical surface was observed. Round sapphire tip performance in a saline field is primarily determined by the tip's temperature.

Lifetime testing of sapphire and sculpted silica fiber scalpels.

BACKGROUND AND OBJECTIVE: Sapphire and sculpted silica fiber scalpels were evaluated for performance as they aged. Performance was determined by measuring their useful lifetime, forward transmission, incision depth, and the thermal coagulation thickness at the sides and bottom of the incision. STUDY DESIGN/MATERIALS, AND METHODS: Aging was performed with a chicken breast model. Performance measurements were made at periodic intervals. Sapphire scalpels were cooled with air or saline. RESULTS: The air-cooled, frosted sapphire scalpels had the longest useful lifetime, whereas the saline-cooled, frosted sapphire scalpels had the shortest. Aging deteriorated the forward transmission of the sculpted silica fiber scalpels the most. Little difference was found between the averages of all incision measurements. Two of the saline-cooled, frosted sapphire scalpels fractured during the aging process. CONCLUSION: Aging influences the scalpel lifetime, but there was no evidence that the aging process significantly affected the incision size.