Computed tomography urography

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CT urogram
Specialty Radiology

A computed tomography urography (CT urography or CT urogram) is a computed tomography scan that examines the urinary tract after contrast dye is injected into a vein. [1]

Contents

In a CT urogram, the contrast agent is through a cannula into a vein, allowed to be cleared by the kidneys and excreted through the urinary tract as part of the urine. [1]

Uses

Plain CT urography (without contrast) is used to evaluate stone diseases, calcifications within kidneys, density of renal masses and presence of any bleeding before contrast is given. Then iodinated contrast is given intravenously to evaluate kidney tumours (if any) and urinary tract. CT scan is then taken at 30 to 70 seconds (when the contrast reaches the renal cortex and renal medulla) to evaluate the perfusion and vascularity of the kidneys. CT scan taken at 90 to 180 seconds (when the contrast perfused the whole kidney) to evaluate the characteristics of kidney masses. The contrast starts to drain into the collecting system of the kidneys at 3 minutes after injection and the whole collecting system is well distended with contrast at 8 to 10 minutes. Taking a CT scan at this time is useful to evaluate any strictures or masses from within the ureters or from outside but compressing on the ureters. [2] Contrast CT urography is also useful to monitor whether a tumour is responding to treatment. [3] [4]

Procedure

FIGURE 8. Selected images from a CT Urography protocol CT. 8a is an axial CT image from the renal parenchymal phase. There is a mildly enhancing soft tissue mass in the left renal pelvis (arrow) consistent with a transitional cell carcinoma. Figure 8b (coronal reformats) and 8c (left oblique coronal reformats) demonstrate the double bolus technique of CT Urography. These images confirm soft tissue mass (arrows) in the renal pelvis with contrast excretion into the collecting system (arrowheads). Renal parenchymal phase CT of transitional cell carcinoma.jpg
FIGURE 8. Selected images from a CT Urography protocol CT. 8a is an axial CT image from the renal parenchymal phase. There is a mildly enhancing soft tissue mass in the left renal pelvis (arrow) consistent with a transitional cell carcinoma. Figure 8b (coronal reformats) and 8c (left oblique coronal reformats) demonstrate the double bolus technique of CT Urography. These images confirm soft tissue mass (arrows) in the renal pelvis with contrast excretion into the collecting system (arrowheads).

CT urography (CTU) is commonly used in the evaluation of hematuria, and specifically tailored to image the renal collecting system, ureters and bladder in addition to the renal parenchyma.[ citation needed ]

Before the procedure, a person is often asked about things that might put them at risk – for example pregnancy or an allergy to contrast. [5] [3] They are asked to drink water, and not to urinate, so that the bladder is full. [5] [3] Metal objects such as earrings, which might produce artefact on the image, are removed. [3] An intravenous cannula is inserted and contrast dye is injected through this during the scan. [5] The scan involves a person lying down on a table that is put through a CT Scanner. [5]

The CT scan will image the urinary tract, including the kidney, ureters, bladder, and urethra. [3] It does this by taking many cross-sectional images that can be computationally arranged so as to provide 3D information. [3] The scan itself usually involves a CT scan without contrast (a non-contrast phase), a CT scan while the contrast is within the kidneys (a parenchymal phase), and a CT scan taken while the contrast travels through the renal tract (an excretory phase). [4]

Risks

A person may have an allergy to the contrast dye. When this occurs, it is usually mild, causing symptoms such as an itch or a rash, [5] however rarely causes a serious reaction such as anaphylaxis that may impair breathing. [3] The contrast dye may not all go inside the vein at the cannula site, and if it extravasates, it may cause pain or bruising to the local area. [3] The scan involves radiation, which may increase the risk of future cancers by a very small amount, [3] or prove damaging to a pregnancy. [3] Additionally, the dye used can damage kidney function. [3]

Related Research Articles

<span class="mw-page-title-main">Bladder</span> Organ in vertebrates that collects and stores urine from the kidneys before disposal

The bladder is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In placental mammals, urine enters the bladder via the ureters and exits via the urethra. In humans, the bladder is a distensible organ that sits on the pelvic floor. The typical adult human bladder will hold between 300 and 500 ml before the urge to empty occurs, but can hold considerably more.

<span class="mw-page-title-main">Ureter</span> Tubes used in the urinary system in most animals

The ureters are tubes composed of smooth muscle that transport urine from the kidneys to the urinary bladder. In an adult human, the ureters typically measure 20 to 30 centimeters in length and about 3 to 4 millimeters in diameter. They are lined with urothelial cells, a form of transitional epithelium, and feature an extra layer of smooth muscle in the lower third to aid in peristalsis. The ureters can be affected by a number of diseases, including urinary tract infections and kidney stone. Stenosis is when a ureter is narrowed, due to for example chronic inflammation. Congenital abnormalities that affect the ureters can include the development of two ureters on the same side or abnormally placed ureters. Additionally, reflux of urine from the bladder back up the ureters is a condition commonly seen in children.

<span class="mw-page-title-main">Renal cell carcinoma</span> Medical condition

Renal cell carcinoma (RCC) is a kidney cancer that originates in the lining of the proximal convoluted tubule, a part of the very small tubes in the kidney that transport primary urine. RCC is the most common type of kidney cancer in adults, responsible for approximately 90–95% of cases. It is more common in men. It is most commonly diagnosed in the elderly.

<span class="mw-page-title-main">Hematuria</span> Presence of blood in urine

Hematuria or haematuria is defined as the presence of blood or red blood cells in the urine. "Gross hematuria" occurs when urine appears red, brown, or tea-colored due to the presence of blood. Hematuria may also be subtle and only detectable with a microscope or laboratory test. Blood that enters and mixes with the urine can come from any location within the urinary system, including the kidney, ureter, urinary bladder, urethra, and in men, the prostate. Common causes of hematuria include urinary tract infection (UTI), kidney stones, viral illness, trauma, bladder cancer, and exercise. These causes are grouped into glomerular and non-glomerular causes, depending on the involvement of the glomerulus of the kidney. But not all red urine is hematuria. Other substances such as certain medications and foods can cause urine to appear red. Menstruation in women may also cause the appearance of hematuria and may result in a positive urine dipstick test for hematuria. A urine dipstick test may also give an incorrect positive result for hematuria if there are other substances in the urine such as myoglobin, a protein excreted into urine during rhabdomyolysis. A positive urine dipstick test should be confirmed with microscopy, where hematuria is defined by three or more red blood cells per high power field. When hematuria is detected, a thorough history and physical examination with appropriate further evaluation can help determine the underlying cause.

<span class="mw-page-title-main">Pyelonephritis</span> Inflammation of the kidney

Pyelonephritis is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications may include pus around the kidney, sepsis, or kidney failure.

<span class="mw-page-title-main">Hydronephrosis</span> Dilation of the renal pelvis due to obstruction of urine flow

Hydronephrosis describes hydrostatic dilation of the renal pelvis and calyces as a result of obstruction to urine flow downstream. Alternatively, hydroureter describes the dilation of the ureter, and hydronephroureter describes the dilation of the entire upper urinary tract.

<span class="mw-page-title-main">Diatrizoate</span> Chemical compound

Diatrizoate, also known as amidotrizoate, Gastrografin, is a contrast agent used during X-ray imaging. This includes visualizing veins, the urinary system, spleen, and joints, as well as computer tomography. It is given by mouth, injection into a vein, injection into the bladder, through a nasogastric tube, or rectally.

<span class="mw-page-title-main">Nephrostomy</span> Surgical procedure that creates a long-term opening between the kidney and the skin

A nephrostomy or percutaneous nephrostomy is an artificial opening created between the kidney and the skin which allows for the urinary diversion directly from the upper part of the urinary system. It is an interventional radiology/surgical procedure in which the renal pelvis is punctured whilst using imaging as guidance. Images are obtained once an antegrade pyelogram, with a fine needle, has been performed. A nephrostomy tube may then be placed to allow drainage.

Pyelogram is a form of imaging of the renal pelvis and ureter.

<span class="mw-page-title-main">Computed tomography angiography</span> Medical investigation technique

Computed tomography angiography is a computed tomography technique used for angiography—the visualization of arteries and veins—throughout the human body. Using contrast injected into the blood vessels, images are created to look for blockages, aneurysms, dissections, and stenosis. CTA can be used to visualize the vessels of the heart, the aorta and other large blood vessels, the lungs, the kidneys, the head and neck, and the arms and legs. CTA can also be used to localise arterial or venous bleed of the gastrointestinal system.

<span class="mw-page-title-main">Ureterostomy</span>

A ureterostomy is the creation of a stoma for a ureter or kidney.

<span class="mw-page-title-main">Abdominal x-ray</span>

An abdominal x-ray is an x-ray of the abdomen. It is sometimes abbreviated to AXR, or KUB.

<span class="mw-page-title-main">Ovarian vein syndrome</span> Medical condition

Ovarian vein syndrome is a rare condition in which a dilated ovarian vein compresses the ureter. This causes chronic or colicky abdominal pain, back pain and/or pelvic pain. The pain can worsen on lying down or between ovulation and menstruation. There can also be an increased tendency towards urinary tract infection or pyelonephritis. The right ovarian vein is most commonly involved, although the disease can be left-sided or affect both sides. It is currently classified as a form of pelvic congestion syndrome.

Urologic diseases or conditions include urinary tract infections, kidney stones, bladder control problems, and prostate problems, among others. Some urologic conditions do not affect a person for that long and some are lifetime conditions. Kidney diseases are normally investigated and treated by nephrologists, while the specialty of urology deals with problems in the other organs. Gynecologists may deal with problems of incontinence in women.

<span class="mw-page-title-main">Ureteral cancer</span> Medical condition

Ureteral cancer is cancer of the ureters, muscular tubes that propel urine from the kidneys to the urinary bladder. It is also known as ureter cancer, renal pelvic cancer, and rarely ureteric cancer or uretal cancer. Cancer in this location is rare. Ureteral cancer becomes more likely in older adults, usually ages 70–80, who have previously been diagnosed with bladder cancer.

<span class="mw-page-title-main">Computed tomography of the abdomen and pelvis</span>

Computed tomography of the abdomen and pelvis is an application of computed tomography (CT) and is a sensitive method for diagnosis of abdominal diseases. It is used frequently to determine stage of cancer and to follow progress. It is also a useful test to investigate acute abdominal pain. Renal stones, appendicitis, pancreatitis, diverticulitis, abdominal aortic aneurysm, and bowel obstruction are conditions that are readily diagnosed and assessed with CT. CT is also the first line for detecting solid organ injury after trauma.

<span class="mw-page-title-main">Renal ultrasonography</span> Examination of one or both kidneys using medical ultrasound

Renal ultrasonography is the examination of one or both kidneys using medical ultrasound.

The genitourinary tract, or simply the urinary tract, consists of the kidneys, ureters, bladder, and the urethra. The kidney is the most frequently injured. Injuries to the kidney commonly occur after automobile or sports-related accidents. A blunt force is involved in 80-85% of injuries. Major decelerations can result in vascular injuries near the kidney's hilum. Gunshots and knife wounds and fractured ribs can result in penetrating injuries to the kidney.

Ultrasound of the urinary tract involves the use of an ultrasound probe to image parts of the urinary tract. The urinary tract is the path that urine follows after it is formed within the kidneys, and involves a left and right ureter, the bladder, and the urethra.

Ureteric stricture (ureteral stricture) is the pathological narrowing of the ureter which may lead to serious complications such as kidney failure.

References

  1. 1 2 Radiology (ACR), Radiological Society of North America (RSNA) and American College of. "Urography". www.radiologyinfo.org. Retrieved 4 July 2020.
  2. ↑ Kawashima, Akira; Vrtiska, Terri J.; LeRoy, Andrew J.; Hartman, Robert P.; McCollough, Cynthia H.; King, Bernard F. (October 2004). "CT Urography". RadioGraphics. 24 (suppl_1): S35–S54. doi:10.1148/rg.24si045513. ISSN   0271-5333.
  3. 1 2 3 4 5 6 7 8 9 10 11 "CT urogram | Bladder cancer | Cancer Research UK". www.cancerresearchuk.org. Retrieved 2020-07-04.
  4. 1 2 Noorbakhsh, Abraham; Aganovic, Lejla; Vahdat, Noushin; Fazeli, Soudabeh; Chung, Romy; Cassidy, Fiona (December 2019). "What a difference a delay makes! CT urogram: a pictorial essay". Abdominal Radiology. 44 (12): 3919–3934. doi:10.1007/s00261-019-02086-0. ISSN   2366-004X. PMC   8882435 . PMID   31214728.
  5. 1 2 3 4 5 "Computerized tomography (CT) urogram - Mayo Clinic". www.mayoclinic.org. Retrieved 2020-07-04.
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