Contrast Enhanced Ultrasound for Renal Obstruction

Participants will undergo an ultrasound contrast evaluation of both kidneys. This will include placement of an intravenous (IV) catheter in a vein and the delivery of Definity ultrasound contrast agent through the IV. Imaging will be completed for each kidney. The proposed total dose for adult patients will not exceed 20 microliters/kilograms (kg). Each individual dose not to exceed 10 microliters/kg. At initiation of patient studies, the dose will start at 10 microliters/kg for the first injection and a second 10 microliters/kg dose to evaluate the contralateral kidney. However, if ultrasound findings in patient studies demonstrate a dose that is too high (unable to make accurate ultrasound assessment), the dose will be reduced.