Computed tomography urography

Computed Tomography Urography

Renal parenchymal phase CT of transitional cell carcinoma

Computed Tomography Urography (CTU) is a specialized imaging technique used to evaluate the urinary system, including the kidneys, ureters, and bladder. It combines the use of computed tomography (CT) scanning with the administration of a contrast agent to provide detailed images of the urinary tract.

Purpose

CTU is primarily used to diagnose and evaluate conditions affecting the urinary tract. It is particularly useful for detecting urinary tract stones, tumors, infections, and congenital abnormalities. CTU can also be used to assess the extent of urinary tract injuries and to plan surgical interventions.

Procedure

The CTU procedure involves the intravenous injection of an iodinated contrast agent, which enhances the visibility of the urinary tract structures on the CT images. The patient is positioned on the CT table, and images are acquired in multiple phases:

• Non-contrast phase: Initial images are taken without contrast to identify calcifications and stones.
• Corticomedullary phase: Images are taken shortly after contrast injection to visualize the renal cortex and medulla.
• Nephrographic phase: Images are acquired to assess the renal parenchyma and detect masses or lesions.
• Excretory phase: Delayed images are taken to visualize the ureters and bladder as the contrast is excreted through the urinary tract.

Advantages

CTU offers several advantages over traditional imaging techniques such as intravenous pyelography (IVP):

• Higher resolution: CTU provides high-resolution images that allow for detailed evaluation of the urinary tract.
• Multiplanar imaging: CTU can produce images in multiple planes, aiding in the assessment of complex anatomical structures.
• Rapid acquisition: The procedure is quick, reducing the time the patient needs to remain still.

Risks and Considerations

While CTU is generally safe, it does involve exposure to ionizing radiation. The use of contrast agents can also pose a risk of allergic reactions or contrast-induced nephropathy, particularly in patients with pre-existing kidney disease. It is important to assess the patient's medical history and kidney function before the procedure.

Alternatives

Alternatives to CTU include ultrasound, magnetic resonance urography (MRU), and traditional IVP. Each modality has its own indications, advantages, and limitations, and the choice of imaging technique depends on the clinical scenario and patient factors.

Related Pages

• Computed tomography
• Intravenous pyelogram
• Magnetic resonance imaging
• Ultrasound