Abstract: The present invention relates to a method of in vivo optical imaging, of the blood vessels and/or blood pool of a mammalian subject, which comprises an optical imaging contrast agent. The optical imaging agents comprise conjugates of far-red or near-infrared dyes with synthetic polyethyleneglycol (PEG) polymers having a molecular weight in the range 15-45 kDa. Also disclosed are methods of treatment monitoring, methods of diagnosis and medical uses involving the contrast agents.

Abstract: Ultrasound contrast agents of the phase shift colloid type, comprising emulsions of volatile oils in water, are provided with gas-containing nucleation sites associated with (e.g. within) droplets of the dispersed oil phase, in order to enhance efficacy and control of the liquid-to-gas phase transition.

Abstract: Gas-containing microcapsules useful as imaging agents, e.g. as ultrasound contrast agents, may be prepared by forming a dispersion of gas microbubbles in an aqueous medium comprising a solution or dispersion of a wall-forming material and subsequently inducing direct microencapsulation of these microbubbles by the wall-forming material.

Abstract: The present invention provides a polyethylene glycol (PEG) ester surfactant comprising at least one polyethylene glycol moiety and at least one fatty acyl moiety characterized in that said moieties are linked by a linkage incorporating a biodegradable methylene diester unit of formula (I)--CO.O.C(R.sup.1)(R.sup.2).O.CO-- (I)where R.sup.1 and R.sup.2 may, for example, each be a hydrogen atom or a monovalent organic group attached through a carbon atom or R.sup.1 and R.sup.2 together may, for example, form a divalent organic group attached through carbon atoms.