Abstract: Phospholipid liposomes are provided having a lipid bilayer surrounding a confined composition which includes a gas or a gas precursor. The liposomes can be administered to a patient and can be detected in vivo by ultrasound techniques which permit organ imaging.

Abstract: Amines, including proteins and polypeptides covalently coupled with a chelating agent such as diethylenetriaminepentaacetic acid (DTPA) can be labeled with .sup.99m Tc in the presence of a stannous reducing agent at near neutral pH by maintaining the protein concentration at a low level and the DTPA concentration at a high level. The .sup.99m Tc is labeled to the protein through the DTPA sites linked to the protein. Utilizing .sup.111 In labeled proteins as controls, it is shown that the .sup.99m Tc labeled proteins are labeled at the DTPA sites and that they exhibit in vivo stabilities equal to that of the .sup.111 In labeled proteins.

Abstract: Phospholipid liposomes are provided having an outer layer including a cholesterol derivative such as a cholesterol ester and an aqueous medium confined by the layer which includes a tracer agent, a cytoxic agent or a therapeutic agent. The liposomes are adapted for specific organ targeting.

Abstract: A dicyclic dianhydride rapidly and efficiently couples with a broad variety of amines such as polypeptides and proteins in non-aqueous or aqueous media and then may be chelated with a wide choice of radioisotope metallic cations to yield a radio-labeled product that is stable in vivo. A simple 1-step synthesis of the coupled amine in aqueous solution of neutral pH is described which requires only a few minutes time and with little accompanying hydrolysis.