Abstract: A system and method for positioning a device at a desired location in a tubular organ such as an artery. A three-dimensional reconstruction of the organ is obtained, and the desired location is marked in the reconstruction. The device is inserted into the organ and an image is obtained of the device and organ. The reconstruction with the marked location is projected onto a plane from the perspective of the image and the projection and image are superimposed. If the device is not at the desired location, the device is repositioned in the organ and an additional image of the device is obtained. The reconstruction is then projected onto a plane from the perspective of the additional image and the additional image and the projection are superimposed. This process is repeated, as required, until the device is in the desired location.

Abstract: A method for processing an image of coronary arteries given by an intensity function I(x,y). A function z(x,y) is obtained describing the heart surface. The image is then processed to produce an image having an intensity function I?(x,y) where I? is obtained in a calculation involving the function z. The method may be used to enhance the stereoscopic effect of a stereo pair of images of coronary arteries.

Abstract: A method for processing an image of coronary arteries given by an intensity function I(x,y). A function z(x,y) is obtained describing the heart surface. The image is then processed to produce an image having an intensity function I′(x,y) where I′ is obtained in a calculation involving the function z. The method may be used to enhance the stereoscopic effect of a stereo pair of images of coronary arteries.

Abstract: Infrared, visible or mm. radiation is screened by an aerosol comprising flakes (0.03-0.3.times.1.5-20 microns) of aluminum metal composition, having a mass extinction coefficient of at least 4.5 m.sup.2 /g in respect of infrared radiation and at least 3.5 m.sup.2 /g in respect of visible radiation. The invention includes also the flakes per se, and formulations containing them, the flakes being additionally characterized by the facts that the amount of manufacturing process additive with which they are coated has been reduced to between 0 and 2.5 weight percent, and that they have a bulk density at least 0.5, preferably at least 1.5 g/cc. The reduction in the coating additive may be achieved by modifying the amount of additive used in the manufacturing process, or by treating the conventionally manufactured flakes with solvents to reduce the amount of coating additive to the desired level.