. . "In addition, the inclusion of starch or dextrins, a sugar polyester and/or an inflating agent such as methylene chloride, 1,1,2-trichlorotrifluoroethane (FREON 113, EM Science, Gibbstown, N.J. ) or perfluorohexane, will result in microbubbles with an increased in vivo half-life." . .