Gadolinium-Based-Contrast-Agents (GBCA) Enhancement During MR Urography

A retrospective review will be performed of all functional MRI urography (fMRU) cases at two institutions (Children's Hospital of Philadelphia and Vanderbilt Children's Hospital). Over 1000 studies have been performed between the institutions and the normal studies will be selected based on radiology reports and reviewed to confirm they are normal. The fMRU is performed with Gadolinium based contrast agents (GBCAs), initially was performed with Magnevist, then switched to Gadavist, and most recently converted to Dotarem. The fMRU software for analysis of the functional data provides enhancement curves of the aorta and kidneys. fMRU enhancement curves are generated by drawing regions of interest in the aorta and renal parenchyma and calculating the average signal intensity over time. A comparison of the enhancement curves will be performed of the three GBCAs in the normal pediatric population. The enhancement curves will provide peak enhancement values within the aorta and kidneys (Time to peak = TTP) and allow comparison between the GBCAs. The enhancement intensity versus time will be evaluated for each GBCAs, providing an evaluation of how long renal parenchymal enhancement is maintained. Additional functional data will be reviewed such as calyceal transit time (CTT) and renal transit time (RTT).