الفهرس 
Normal CT Anatomy of the Urinary TractOnly 14 pages are availabe for public view
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Abstract
Haematuria is a common problem that can be a sign of a number of benign and malignant underlying diseases. Many different imaging modalities have been used in the evaluation of patients with haematuria, and patients frequently require multiple examinations for work-up. Multi-slice CT urography has become the most useful imaging test of the urinary tract. It provides a single noninvasive examination of the kidneys, ureters, and urinary bladder in one test. As a result, CT urography is the current modality of choice for evaluation of painless gross or microscopic haematuria. I.V. contrast media injection schemes are closely related to the number and timing of CT data acquisition. Two major approaches have been followed : a single bolus of contrast media, combined with a three phase study using unenhanced, nephrographic and excretory phase series, versus a split-bolus contrast media injection, combined with a two phase study using unenhanced and a combined nephrographic-excretory phase series. Three main 3D visualization techniques currently are used on workstations: multi-planar reformation (MPR), maximum intensity projections (MIP), and volume-rendering technique (VRT). Multi-slice CT urography allows for identification of urinary stones, renal parenchymal masses, and urothelial abnormalities. It also plays an important role in trauma. Contrast-enhanced multi-slice CT urography performed with a combination of unenhanced, nephrographic-phase, and excretory phase imaging can demonstrate a wide spectrum of disease in these patients with a single study. Unenhanced imaging provides optimal detection of calculi, a common cause of haematuria. In addition, the combination of unenhanced and nephrographic-phase imaging provides outstanding evaluation of renal masses. Findings at excretory-phase imaging mimic IVU findings and allow excellent evaluation of the collecting systems and ureters. Bladder disease , a common cause of haematuria , is often well seen on un-enhanced or excretory-phase images, although cystoscopy may still be necessary. The relatively high radiation dose of multi-phase CTU is a significant limitation of the widespread acceptance of this technique. Multi phase CTU protocol can be associated with effective dose as high as 25-35 mSv, depending upon the number of phases included. Reduced dose should therefore, always be weighed against diagnostic image quality.