Ultrasound contrast agents and their use in urogenital radiology: status and prospects

Ultrasound contrast agents (USCAs) for intravenous use are usually microbub bles with a mean diameter less than that of a red blood corpuscle and fille d with Gras. The USCAs may improve information about tissue characteristics and physiology by enhancing B-mode imaging, all Doppler modalities and by means of contrast-specific imaging, e.g. harmonic and stimulated acoustic i maging. Results from preclinical experiments have been promising, and sever al of these have been reproduced in clinical studies. This includes improve d evaluation of renal vasculature and parenchyma, assessment of vesicourete ral reflux in children, assessment of tubal patency in women, and evaluatio n of prostate diseases and erectile dysfunction in men. Some of the physica l limits of the ultrasound technology, as well as the operator-dependent fa ctors, can probably never be overcome by the use of USCAs; however, the dev elopment of USCAs is now about to provide uroradiologists with potentially efficacious products for the benefit of the patient.