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, we hypothesize that a urodynamic study may be performed with contrast enhanced ultrasound instead of fluoroscopy. We plan to continue enrollment from our feasibility study and perform an efficacy study by recruiting a group of 105 patients under the age of 18, who are willing to undergo their normally schedule UDS using CEvUS to image the study in place of fluoroscopy. The UDS typically consists of two cycles of bladder filling and voiding; we intend replace the use of fluoroscopy and iohexel with ultrasound and sulfur hexafluoride lipid-type A microspheres. This will decrease the time commitment and eliminate radiation exposure for the patient. Data to be analyzed will include images from the study and patient/caregiver preference. Results from the ceVUS images will be compared to images obtained during previous tests imaged with fluoroscopy from the same patients currently enrolled in this study. Bladder shape and morphology, bladder neck configuration and performance, structure of the urethra, presence and degree of vesicoureteral reflux, and active voiding images will all be compared to fluoroscopy images from previous studies. The purpose of the study is to demonstrate that ceVUS is effective as an imaging technique for urodynamic studies, with an ultimate goal of using ceVUS instead of fluoroscopy in all urodynamic and voiding studies in order to decrease pediatric radiation exposure. The hypothesis is that ceVUS will be as effective for imaging urodynamics studies as fluoroscopy.
The investigators will assess the feasibility of replacing fluoroscopy/iodinated contrast with ultrasound/sulfur hexafluoride lipid-type A microspheres during routine urodynamic studies.