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A computed tomography urography (CT urography or CT urogram) is a computed tomography
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.
Before the procedure, a person is often asked about things that might put them at risk – for example pregnancy or an allergy to contrast. They are asked to drink water, and not to urinate, so that the bladder is full. Metal objects such as earrings, which might produce artefact on the image, are removed. An intravenous cannula is inserted and contrast dye is injected through this during the scan. The scan involves a person lying down on a table that is put through a CT Scanner.
The CT scan will image the urinary tract, including the kidney, ureters, bladder, and urethra. It does this by taking many cross-sectional images that can be computationally arranged so as to provide 3D information. 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).
scan
Scan may refer to:
Acronyms
* Schedules for Clinical Assessment in Neuropsychiatry (SCAN), a psychiatric diagnostic tool developed by WHO
* Shared Check Authorization Network (SCAN), a database of bad check writers and collection agency for bad ...
that examines the urinary tract
The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, c ...
after contrast dye is injected into a vein.
In a CT urogram, the contrast agent is through a cannula into a vein, allowed to be cleared by the kidneys and excreted
Excretion is a process in which metabolic waste
is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after lea ...
through the urinary tract as part of the urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra.
Cellular ...
.
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. Theniodinated contrast
Iodinated contrast is a form of intravenous radiocontrast agent containing iodine, which enhances the visibility of vascular structures and organs during radiographic procedures. Some pathologies, such as cancer, have particularly improved visib ...
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
The renal cortex is the outer portion of the kidney between the renal capsule and the renal medulla. In the adult, it forms a continuous smooth outer zone with a number of projections (cortical columns) that extend down between the pyramids. It ...
and renal medulla
The renal medulla is the innermost part of the kidney. The renal medulla is split up into a number of sections, known as the renal pyramids. Blood enters into the kidney via the renal artery, which then splits up to form the segmental arteries whi ...
) 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. Contrast CT urography is also useful to monitor whether a tumour is responding to treatment.
Procedure
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.
Before the procedure, a person is often asked about things that might put them at risk – for example pregnancy or an allergy to contrast. They are asked to drink water, and not to urinate, so that the bladder is full. Metal objects such as earrings, which might produce artefact on the image, are removed. An intravenous cannula is inserted and contrast dye is injected through this during the scan. The scan involves a person lying down on a table that is put through a CT Scanner.
The CT scan will image the urinary tract, including the kidney, ureters, bladder, and urethra. It does this by taking many cross-sectional images that can be computationally arranged so as to provide 3D information. 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).
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, however rarely causes a serious reaction such as anaphylaxis that may impair breathing. 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. The scan involves radiation, which may increase the risk of future cancers by a very small amount, or prove damaging to a pregnancy. Additionally, the dye used can damage kidney function.References
{{Urologic procedures Urologic imaging