Urodynamic studies routinely involve instillation of iohexol (OmnipaqueTM), a low osmolality contrast agent, into the bladder followed by fluoroscopic imaging to assess for reflux or variant anatomy of the genitourinary system. Recently, sulfur hexafluoride lipid-type A microspheres (LumasonTM), an ultrasound contrast agent, has been approved in the United States for intravesicular administration in the pediatric population. Contrast enhanced voiding urosonography (CEvUS) is being increasingly utilized in the place of voiding cystourethrograms, with the major advantages being decreased (zero) radiation for the patient, as well as decreased cost. Given the similarity in procedure between urodynamic studies (UDS) and voiding cystourethrograms, the investigators hypothesize that a urodynamic study may be performed with contrast enhanced ultrasound instead of fluoroscopy. The investigators plan to conduct a small feasibility study by recruiting a group of 30 patients under the age of 18, who are willing to undergo their normally scheduled UDS in addition to CEvUS. The UDS typically consists of two cycles of bladder filling and voiding; the investigators intend to replace the use of fluoroscopy and iohexol with ultrasound and sulfur hexafluoride lipid-type A microspheres. This will decrease the time commitment and eliminate radiation exposure for the patient. There will not be a formal analysis of data as the investigators are planning to test the feasibility of the procedure rather than gather any quantitative data. The goal of the study is to eventually implement CEvUS instead of fluoroscopy in all urodynamic and voiding studies if it is found to be a reasonable alternative. This will decrease pediatric radiation exposure, which will be especially important in the patients undergoing several studies each year.
The investigators will assess the feasibility of replacing fluoroscopy/iodinated contrast with ultrasound/sulfur hexafluoride lipid-type A microspheres during routine urodynamic studies.