MR Urography

MRI of the urinary tract from kidneys through ureters to bladder. Radiation-free alternative to CT urography for evaluating obstruction, congenital anomalies, and urothelial pathology.

MR urography provides comprehensive imaging of the entire urinary tract — kidneys, renal pelves, ureters, and bladder — without ionising radiation. The examination uses a combination of T2-weighted sequences (which show static fluid in the collecting system as bright signal) and, when contrast is administered, T1-weighted excretory-phase images that trace gadolinium through the nephrons into the collecting system and ureters. The technique is particularly valuable for evaluating ureteric obstruction (identifying the level and cause of hydronephrosis), congenital urinary tract anomalies (duplex collecting systems, ectopic ureters, ureteroceles), and surveillance of urothelial tumours. It is the preferred modality for pregnant patients and children where CT radiation exposure is a concern, and for patients with iodinated contrast allergy who cannot undergo CT urography. The examination may be performed with or without gadolinium depending on the clinical indication. The static T2-weighted MR urogram is contrast-free and sufficient for many obstructive and congenital indications; the excretory-phase study adds functional information about renal excretion and ureteric drainage.