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CT UROGRAPHYQ: What is CT Urography?A: CT Urography is a sophisticated, specialized radiological examination designed to evaluate the urinary tract (kidneys, ureters and bladder) using computed tomography (CT). This exam has been introduced by RMG to replace or complement the IVP (or excretory Urogram). CT produces slices or cross-sectional images through the body enabling exquisite and detailed evaluation of the internal organs. The CT Urogram is optimally designed to specifically evaluate the urinary tract with the added advantage of visualizing all of the other inta-abdominal and pelvic structures as well. These examinations are best performed using Spiral CT scanners, and RMG provides the latest state-of-the-art multi-slice spiral CT scanners at all of its facilities.
Q: What are the indications for this study? Kidney stones are very common. Stones or calculi cause problems when they block or obstruct the renal collecting system (ureter). When this happens, patients can experience intense, spasmodic flank pain (renal colic). Historically, patients with renal colic have been evaluated with intravenous urography/pyelography, popularly known as the IVP. While very accurate in detecting calculi and ureteral obstruction, this examination requires an injection of intravenous contrast material followed by serial plain films of the abdomen. This carries some risk, albeit slight, of allergic reaction to the contrast material. In addition, if the ureter is completely blocked by a stone, the IVP exam may be quite lengthy, sometimes requiring several hours. CT Urography without IV contrast has now been shown to be superior to the IVP in evaluating patients with suspected kidney stones. Patients do not require any injections or special preparation, and the examination is completed in seconds. Unlike the IVP, in patients whose flank pain is not related to kidney stones, CT often makes the alternate diagnosis. Painless hematuria (blood in the urine), even if microscopic, requires prompt medical attention. In virtually all cases, a thorough evaluation is necessary to exclude malignancy arising from the kidneys, ureters or bladder. Traditionally, patients are referred to a urologist who typically requests an IVP and performs cystoscopy (endoscopy of the bladder). The IVP's strength lies in its ability to visualize the renal collecting system or ureters. Some kidney cancers however, particularly small masses, may not be detectable with the IVP. Recognizing this shortcoming, CT Urography with IV contrast has emerged. This combines the strengths of CT and the IVP into one comprehensive examination with exceptional evaluation of the kidneys and collecting systems. The CT urogram with contrast is, therefore, often ordered instead of the IVP to evaluate painless hematuria. Q: Is there any risk?A: CT urography without contrast (usually performed to evaluate acute flank pain) has no significant risk. The amount of radiation received during this exam is minimal and should cause no concern except for pregnant patients, in which case an alternate or limited exam is usually performed. CT urography with contrast does require an injection of "x-ray dye." While very safe, this injection carries a small risk of allergic reaction, which may rarely be serious. For additional information on the risks of iodinated contrast material or “x-ray dye,” please go to “Patient Services” on our home page, and select “Procedure Info”. Then, click on “Contrast Material” for a detailed discussion on x-ray contrast. Q: Is a contrast injection ever necessary to evaluate kidneys stones?A: Yes. Occasionally, a CT urogram without contrast will be converted by the radiologist to a contrast study in order to confirm the diagnosis and to provide additional useful information to your referring physician.
Q: Are there any patients who should not undergo CT Urography? A: Although CT urography is more costly than the IVP, it is considerably safer, more accurate and provides much more information. In addition, it is faster and more comfortable. At RMG we have aggressively priced this examination so that it is affordable to our patients. For more information regarding fees for this and other examinations, please return to the home page of this website, and click on “Our Fees.” References:
2. Darymple NC, et al. The value of unenhanced spiral computerized tomography in the management of acute flank pain. J Urol 1998; 159(3): 735-740. 3. McNicholas MMJ, et al. Excretory Phase CT Urography for Opacification of the Urinary Collecting System. AJR 1998; 170:1261-1267. |
