Abstract: An imaging agent for ultrasound to be administered into a vein is provided. More specifically, an imaging agent for ultrasound containing microbubbles, which has a long-life and is stable within a human body even after is has passed through a lung, and a method for producing the same, are provided.A method for producing an imaging agent for ultrasound comprises a mixing step wherein a mixture of water, Sodium Stearate, Saponin and CaCl.sub.2 and gas are mixed by a homogenizer for forming bubbles, and a separation step wherein bubbles having a desired size are separated according to their buoyancy after the mixing step. The mixing step further includes two stages, i.e., a low speed mixing stage and a high speed mixing stage. In the low speed mixing stage, a shaft of the homogenizer is immersed into a solution containing a preset amount of Sodium Stearate, Saponin, and CaCl.sub.2, which is mixed at a low rotation speed for a given period of time and is then left for a given period.

Abstract: An imaging agent for ultrasound to be administered into a vein is provided. More specifically, an imaging agent for ultrasound containing microbubbles, which has a long-life and is stable within a human body even after is has passed through a lung, and a method for producing the same, are provided.A method for producing an imaging agent for ultrasound comprises a mixing step wherein a mixture of water, Sodium Stearate, Saponin and CaCl.sub.2 and gas are mixed by a homogenizer for forming bubbles, and a separation step wherein bubbles having a desired size are separated according to their buoyancy after the mixing step. The mixing step further includes two stages, i.e., a low speed mixing stage and a high speed mixing stage. In the low speed mixing stage, a shaft of the homogenizer is immersed into a solution containing a preset amount of Sodium Stearate, Saponin, and CaCl.sub.2, which is mixed at a low rotation speed for a given period of time and is then left for a given period.