When is MRU contraindicated?
MRU does not have the spatial resolution of CTU for detecting small urothelial lesions, thus making it inferior to CTU, IVU, and retrograde pyelography for evaluation of the collecting systems. MRU is a superb technique for delineating an obstructed urinary tract and for evaluating congenital anomalies. It is contraindicated in patients with a prior history of adverse reaction to gadolinium-based contrast material, in pregnant patients, and in patients with general contraindications to MRI, such as when certain metallic or electronic devices are present.
