15/08/2025
MRU stands for Magnetic Resonance Urography — an MRI-based technique used to evaluate the urinary tract (kidneys, ureters, bladder) without ionizing radiation.
There are two main techniques for MRU, often used alone or in combination:
1. Static-fluid MRU (T2-weighted)
Principle: Uses heavily T2-weighted sequences, so fluid (urine) appears very bright while surrounding tissues are darker.
Purpose: Best for detecting obstruction, congenital anomalies, or collecting system dilatation.
Technique:
Patient usually well hydrated.
No contrast required.
Sequences: Heavily T2-weighted single-shot fast spin echo (SSFSE / HASTE) or 3D T2-weighted sequences.
Images can be reformatted in multiple planes.
Advantages: Works even with impaired renal function; shows the urinary tract filled with static or slow-flowing urine
2. Excretory MRU (Contrast-enhanced, T1-weighted)
Principle: Uses gadolinium-based contrast to visualize the urinary tract as the contrast is filtered and excreted by the kidneys.
Purpose: Evaluates function and anatomy — useful for detecting ureteric strictures, tumors, and differentiating obstructive vs. non-obstructive dilatation.
Technique:
Pre-contrast T1 images for baseline.
Administer gadolinium intravenously.
T1-weighted 3D gradient-echo sequences taken dynamically during nephrographic and excretory phases.
Diuretics (e.g., furosemide) may be given to speed excretion and improve ureter visualization.
Advantages: Functional information, better for non-dilated ureters.
Typical Protocol
1. Patient preparation: Hydration, sometimes diuretic before scan.
2. Sequences:
Coronal and axial T2-weighted images (static-fluid MRU).
T1-weighted pre- and post-contrast images (excretory MRU).
3D reconstruction for anatomical overview.
3. Optional breath-hold techniques to reduce motion artifacts
Exam done on Philips Free helium MRI system Ambition X 1.5 T by Alaa Alghazaly
Iraq / Karbala
Imam Zain alabdeen hospital
