A computerized axial tomography scan is performed by obtaining axial x-rays images using computerized reconstruction. Patients are usually given an oral contrast liquid by mouth to aid in imaging the alimentary tract. See a CAT scan of normal kidneys.
Usefulness: A CAT scan is helpful in delineating solid renal, retroperitoneal or pelvic masses in children. It can detect lymphatic, liver and lung metastases. CAT scans can be enhanced by using intravenous iodinated contrast material. This allows one to detect perfusion and concentration of the contrast by the kidney.
Limitations: A CAT scan is an invasive test. It requires placement of an intravenous line. It also exposes a child to a significant amount of radiation. It is rarely the first exam to obtain. The majority of abdominal masses in children are from the urinary tract and most of these are cystic (hydronephrosis). An ultrasound is, therefore, a better initial exam in a child with an abdominal mass. Although significant renal function is required to concentrate and excrete the contrast material, CAT scans are relatively sensitive in detecting and comparing renal function between two kidneys. Most young children require sedation to undergo a CAT scan. CAT scans are relatively expensive.
Indications: A CAT scan is very useful in evaluating solid abdominal masses in children. A child suspected of having a genitourinary tumor may benefit from a CAT scan.
CAT Scan Example
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©David A. Hatch, M.D., 1996