MRI Urography, Types of MR Urography, Indications of MR Urography, Advantages of MR Urography.

MRI Urography (MR Urography or MRU) is a non-invasive imaging technique used to evaluate the kidneys, ureters, and urinary bladder. It combines standard MRI imaging with specialized sequences and sometimes contrast agents to provide detailed images of the urinary tract.

🔹 Types of MR Urography

1. Static-Fluid MR Urography

   • Uses heavily T2-weighted sequences.

   • Visualizes fluid-filled urinary tract structures (kidney collecting system, ureters, bladder).

   • No contrast required.

   • Best for patients with poor renal function or contraindications to contrast.

2. Excretory (Contrast-Enhanced) MR Urography

   • Uses gadolinium-based contrast agents.

   • Provides functional and anatomical information.

   • Demonstrates excretion of contrast through kidneys, ureters, and bladder.

   • Useful for assessing obstruction, strictures, or urothelial tumors.

🔹 Indications of MR Urography

• Evaluation of congenital anomalies (e.g., duplicated ureters, UPJ obstruction).

• Hydronephrosis and its cause.

• Ureteric obstruction (stone, stricture, external compression).

• Urothelial tumors.

• Vesicoureteral reflux (VUR) assessment.

• Preoperative mapping in donor kidney evaluation.

• Patients allergic to iodinated contrast (alternative to CT urography).

• Patients with renal impairment where iodinated contrast is risky.

🔹 Advantages of MR Urography

• Non-invasive, no ionizing radiation (unlike CT urography).

• Excellent soft-tissue contrast.

• Can combine anatomical + functional assessment.

• Useful in pediatrics and pregnant patients (with non-contrast MRU).

🔹 Limitations

• Longer scan time compared to CT.

• Motion artifacts (breathing, peristalsis).

• Not as sensitive as CT for small urinary stones.

• Gadolinium contraindicated in severe renal failure (risk of NSF).