The MRI Urography is a highly sophisticated, non-invasive imaging method that is capable of giving detailed information about the evaluation of the kidneys, ureters, and urinary bladder. It offers both anatomical and functional information about the urinary tract and does not lead to exposure to patients from ionizing radiation.

The scan may be done without or with an injection of Gadolinium-based contrast medium, depending on the clinical need. In particular, MRI Urography is indicated for patients who are contraindicated for CT Urography due to iodine contrast allergy, concerns about radiation, or reduced kidney function.

MR Urography is used for the detection of structural abnormalities, blockage of urine flow, tumours, congenital defects, infection, or other disorders of the urinary tract with high-resolution multiplanar imaging.

Purpose of MRI Urography

Used to find out about the urinary system and any problems with urine flow or kidney function.

Key Purposes:

• Assess the integrity of the urinary tract.
• Identify urine blockages or stricture.
• Explain what causes hematuria (blood in urine).
• Examine kidney stones if other imaging tests don't provide a diagnosis.
• Identify tumour or abnormal growth.
• Assess congenital abnormalities of the kidneys and ureters.
• Assess urinary tract trauma.

Clinical Indications

MRI Urography may be suggested in the following cases:

• Unexplained hematuria.
• Young children who have recurrent urinary tract infections (UTIs).
• An increase in the amount of urine in the kidneys (hydronephrosis).
• The presence of renal stones and a suspected obstruction are the other reasons for locating the stricture.
• Urethral or suspected UT tumours (both small and large).
• GU birth defects.
• Stones that are not clearly visible on other imaging techniques in the kidney or ureters.
• Pre-surgical planning.
• Post-surgical or post-treatment follow-up.

Procedure of MRI Urography

Before the Scan

• MRI screening for safety is done on:
  • Pacemakers
  • Metallic implants
  • Cochlear implants
  • Surgical clips
• In some cases, testing of kidney function may be needed if there is the intention to have contrast.
• Take off all metal objects (jewelry, watches, hairpins, cards).
• Generally, do not fast unless directed to do so.
• It may require drinking water before the scan to fill the bladder.

During the Scan

• During the MRI scan, you will be lying on the MRI table with your belly down.
• A body coil is used for the acquisition of images.
• Initial non-contrast sequences (T1 and T2) are done.
• Gadolinium contrast is administered if necessary for functional imaging.
• Multiple planes of images are obtained with the potential to generate 3D images.
• The body must be completely immobile; short movements might be needed.

After the Scan

• No isolation or quarantine is needed, and normal activities can be resumed right away.
• If contrast used: drink lots of fluids.
• Reports are obtained within 24 hours.

Techniques Used in MRI Urography

Static-Fluid MR Urography

• Aims to find structures filled with urine fluid, using T2 weighting (T2W).
• No contrast required.
• Ideal for those who have kidney impairment.

Excretory MR Urography

• Uses gadolinium contrast.
• Determines whether the function of both the urinary system and the kidneys is normal or not.

3D MR Urography

• Provides in-depth volumetric imaging.
• The reconstruction is comparable to that obtained from CT urography.

Advantages of MRI Urography

• No radiation exposure.
• Good soft tissue contrast.
• Helps to provide structural and functional information.
• While a patient is allergic to iodine contrast solution, this is a safe choice.
• May be done with or without contrast as necessary.
• Best for repeated follow-Up imaging.
• Excellent anatomical separation with multiplanar imaging.

Limitations

• Longer scan time than CT.
• The patient's movement or breathing can interfere with the process.
• Inferior sensitivity (efficacy) compared to CT for very small stones that may break up over time.
• Cost is higher, and it is not available in certain areas.
• The gadolinium contrast could not be used in patients with severe kidney disease.

Patient Preparation Tips

• Ensure proper clothing, no metal.
• As directed by hydration or fasting directions.
• Provide employees with information on implants, surgeries, or allergies.
• Do not move during the scan.
• For claustrophobics, discuss the sedating option beforehand

What Radiologists Evaluate?

Radiologists look for the following:

• The size, shape and location of the kidneys.
• The histogram shows the renal parenchyma and corticomedullary differentiation.
• Dilation or blockage of the collecting systems.
• The complete course, diameter and obstruction of the ureters.
• Increased thickness of the bladder wall and masses.
• Defects that fill (stones or tumours).
• Patterns of urinary drainage & pattern of contrast in urine.
• Compare the functioning of both kidneys.

Conclusion

MRI Urography is a very useful non-invasive imaging method, which gives a complete assessment of the urinary tract. It is a combination of detailed anatomical imaging and functional assessment, which aids in the diagnosis of various conditions such as obstruction, tumours, congenital disorders, infections, and trauma.

Being non-radiating, it's particularly beneficial for children, young adults, and those who need to take images more than once. MR Urography is a form of exact diagnostic, treatment planning, and Follow-Up imaging that is important for accurate diagnosis, treatment planning, and follow-up in modern urology with the benefit of excellent soft tissue resolution and advanced imaging capabilities.