Colour Doppler signal enhancement of intrarenal vasculature of the rabbit with Perflubron

The colour Doppler signal enhancement of the intrarenal vasculature of the kidney was studied after intravenous infusion of Perflubron. This enhancement was evaluated qualitatively and semi-quantitatively. Nine rabbits received 1 g/kg of a 100% w/v Perflubron emulsion [perfluorooctylbromide (PFOB), Alliance Pharmaceutical] intravenously. Then, two groups of 2 rabbits received 2 and 3 g/kg respectively, and 1 rabbit received 4 g/kg. The kidneys were imaged longitudinally on a colour Doppler unit with a 7.5 MHz transducer. Signal enhancement was evaluated semi-quantitatively by counting the levels of signal threshold that had to be subtracted to reproduce the baseline image. This measurement was performed 1, 3, 5, 10, 30, 45, 60, 90 and 120 min after infusion. We found that detection of very small vessels deep into the parenchyma was possible with Perflubron. In the group that received 1 g/kg Perflubron significant variations in signal enhancement were noted. The curve of mean signal enhancement showed a maximum Doppler signal at about 15 min, which slightly and progressively decreased during the next hour. With the 2, 3 and 4 g/kg doses, enhancement was constant and proportional to the infused dose. Perflubron emulsion allows significant Doppler enhancement on colour flow imaging, providing better visualisation of deep parenchymal small vessels. A dose of 1 g/kg seems adequate for this purpose.Correspondence to: N. Grenier