The present invention describes processes for the preparation of a lipid blend and a uniform filterable phospholipid suspension containing the lipid blend, such suspension being useful as an ultrasound contrast agent. Preparation of the lipid blend The lipid blend may be prepared via an aqueous suspension-lyophilization process or an organic solvent dissolution-precipitation process using organic solvents. In the aqueous suspension-lyophilization process, the desired lipids are suspended in water at an elevated temperature and then concentrated by lyophilization. Preferably a dissolution procedure is used.
