SONOGRAPHY WITH SONICATED ALBUMIN IN THE DETECTION OF VESICOURETERAL REFLUX

The primary radiological procedures for diagnosing vesicoureteral reflux are fluoroscopic and radionuclide cystography. Ultrasonography, with no ionizing radiation, would be useful as a screening tool for the diagnosis of reflux due to its absence of radiation exposure. We evaluated the usefulness of ultrasonography with sonicated albumin in the diagnosis of vesicoureteral reflux. Sonicated albumin contains approximately 3 to 5 X 10(8) microspheres per ml., which are echogenic. Sonicated albumin was tested in vitro, alone, and in human and porcine urine to assess microsphere stability. Urine dilutions, specific gravity, temperature and pH were used as variables. The mode of delivery was also tested in vitro and in vivo. These studies showed that sonicated albumin microspheres were stable over a wide range of chemical variables and urine composition. Sonicated albumin produced an image of uniform echogenicity when it was pre-loaded into a Foley catheter and followed by saline infusion in vitro. Fluoroscopic cystograms, using standard radiopaque contrast media, in 5 Hanford mini-swine in which unilateral reflux had been created previously confirmed the presence of reflux unilaterally. Sonographic cystograms with various dilutions of sonicated albumin in 0.9% sodium chloride (1:100, 1:250, 1:500, 1:750 and 1:1,000) were performed. At a dilution of 1:100 sonicated albumin produced dramatic echogenicity in the bladder and refluxing ureters during sonographic imaging. The microspheres appeared to be stable for prolonged periods (more than 40 minutes), thus allowing for a careful sonographic assessment of the entire genitourinary tract. Sonicated albumin may be valuable for the sonographic detection of vesicoureteral reflux.