Abstract: Ultrasonic contrast media are provided comprising small particles with entrapped gas, where the compositions can be selected for rapid dissolution with production of microbubbles or maintaining the gas in microtubules, microchambers or microcracks, providing for echogenicity. The particles are readily formed by precipitation from a liquid, either solution or melt, of a monomeric material, followed by drying and mechanically reducing the size of the particles.

Abstract: In the inventive method, microbubbles are formed in body liquid or carrier liquid, for example within the genitourinary or digestive systems in order to alter the transmission characteristics thereof to electromagnetic and sonic waves transmitted therethrough, by dissolving therein a solid particulate material, preferably as a suspension in a carrier liquid in which the particulate material is at least temporarily stable, the particles of which are substantially free of microbubbles and have a plurality of gas-filled voids communicating with the surface of the particles and providing nuclei for microbubble formation and the ratio of the mass of the particles to the volume of gas in the voids is sufficient to render the liquid in which the particulate material is dissolved supersaturated with respect to the gas in the voids in the area of the liquid surrounding the microbubbles when they are formed.

Abstract: Microbubbles are formed in a liquid, e.g., blood in order to alter the transmission characteristics thereof to electromagnetic and sonic waves transmitted therethrough, by dissolving therein a solid particulate material, preferably as a suspension in a carrier liquid in which the particulate material is at least temporarily stable, the particles of which are substantially free of microbubbles and have a plurality of gas-filled voids communicating with the surface of the particles and providing nuclei for microbubble formation and the ratio of the mass of the particles to the volume of gas in the voids is sufficient to render the liquid in which the particulate material is dissolved supersaturated with respect to the gas in the voids in the area of the liquid surrounding the microbubbles when they are formed.

Abstract: Microbubbles are formed in a liquid, e.g., blood in order to alter the transmission characteristics thereof to electromagnetic and sonic waves transmitted therethrough, by dissolving therein a solid particulate material, preferably as a suspension in a carrier liquid in which the particulate material is at least temporarily stable, the particles of which are substantially free of microbubbles and have a plurality of gas-filled voids communicating with the surface of the particles and providing nuclei for microbubble formation and the ratio of the mass of the particles to the volume of gas in the voids is sufficient to render the liquid in which the particulate material is dissolved supersaturated with respect to the gas in the voids in the area of the liquid surrounding the microbubbles when they are formed.

Abstract: A method is presented for measuring fluid flow rate in a system having a conduit through which the fluid flows. The method is particularly useful for measuring blood flow rate in a cardiovascular system. A substance which provides a plurality of microbubbles is added to the fluid flow system upstream of the measurement position in the conduit. An ultrasonic pulse is generated from a position opposite and spaced from the conduit as the microbubbles pass therethrough. A reflected ultrasonic image, created by reflection of the pulse from at least the wall of the conduit which is distal from said position, is measured. The fluid flow rate within the conduit is determined from these ultrasonic images using dye dilution techniques. In a living being, the pulse is preferably generated adjacent the rib cage or in the esophagus and the conduit is preferably the heart or the pulmonary artery, whereby, the blood flow rate determined is equal to the volumetric cardiac output rate.

Abstract: Ultrasonic images of flowing streams can provide important information regarding the streams. Herein, a plurality of microbubbles are provided in such streams to enhance such images, aid in tumor detection and treatment, provide mapping of vascularity of tissue masses and measure instantaneous blood flow rate. The preferred microbubbles have a coalescence resistant surface membrane encapsulating a gas of a selected composition, the membrane including non-toxic and non-antigenic organic molecules. Preferrably, the microbubbles have diameters in the 0.5 micron-300 micron range.

Abstract: Pressure within a liquid containing vessel is determined by adding a solid precursor for at least one bubble to the liquid, retaining the precursor in the liquid for a sufficient time for it to form at least one bubble and generate a sonic signal, metering a characteristic of the sonic signal which is representative of the pressure in the liquid and determining the pressure in the liquid from the measured characteristic.