الفهرس 
Normal Anatomy ofOnly 14 pages are availabe for public view
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Abstract
There is no universal agreement about the optimal imaging work-up of hematuria. Traditionally, excretory urography was the standard, but the establishment of this practice preceded the development of multidetector CT urography, which is a single imaging test that comprehensively evaluates the UT.
With MDCT, it has become possible to obtain a large number of very thin section axial overlapping CT images through the entire renal collecting systems, ureters and bladder in a very short period of time during the excretory phase. This has been termed CT urography. This allows for more detailed evaluation of the urothelium.
Multiplanar reformation images provide orthogonal coronal or sagittal or oblique planes, which help to define the location and extent of the lesions shown on axial CT images. MIP processing has several advantages: it allows visualization of structures that do not lie in a single plane. So it can visualize high-density structures, such as contrast-filled renal arteries and the whole collecting system in such a way as angiograms or urogram. Caliceal details were occasionally better seen on MIP images.
MPR is the most commonly used reformation. Two dimensional reformatted sagittal and coronal images are reconstructed from the stack of axial image data. It helps to define the location and extent of the lesions shown on axial CT images. A known limitation of MPR is that visualized structures must be in the same plane.
MIP, MPR, and volume rendering are used to generate images simulating IVU. The main advantage of these images was that they were more familiar to our clinical colleagues, because they closely resemble those of IVU. Additionally, these images could be more effectively used for preoperative planning.
The protocol of MDCTU used a three plane examination.
- Unenhanced CT from the kidneys through the bladder is used to detect calculi and as a baseline for characterization of renal parenchymal masses.
- Nephrographic phase-enhanced through the kidneys is used to detect and characterize renal parenchymal masses.
- Excretory phase CT is used to detect urothlial lesions.
MDCTU is now described as a comprehensive test, which can be performed as a substitute ”one stop” imaging test for a number of imaging studies, thereby saving time, hospital visits and cost, and potentially shortening the duration of diagnostic evaluation for urinary tract pathology.
The major concern, which may limit universal acceptance of MDCTU, is the radiation dose associated with the procedure.
Radiation dose with MDCTU clearly significantly exceeds IVU. However, radiation dose can be reduced by adapting scanning parameters for each phase of MDCTU and by reduction of number of phase.
MDCTU should be considered as a first line investigation in patients with hematuria when risk of disease outweighs, risk of radiation exposure (ie, patients at high risk of urologic cancer).
This study proved that MDCT is the most sensitive and specific test for the diagnosis of urinary tract calculi and also for detection and characterization of renal masses.
Regarding upper urothiliam malignancy, our results were sensitivity 96%, and specificity between 98% and 100%. Therefore, MDCTU rather than excretory urography should be the first choice noninvasive imaging modality for diagnosing upper urinary tract transitional cell carcinoma.
Also, CT urography can be helpful in assessing the upper tracts for synchronous or metachronous urothelial neoplasms in patients with current or previously treated bladder cancers. CT urography is particularly important in patients who have undergone cystectomy, in whom, as a result of surgery, retrograde pyelography or ureteroscopy may be technically challenging.
MDCT was used to detect 80% of bladder tumors < 5mm in this study. Diagnostic accuracy improved when the data were reconstructed as thin sections with MPR, which also used to improve the detection of bladder tumors in areas contiguous with other anatomic structures and difficult to analyze.
Therefore, CT urography is an accurate, noninvasive test for detecting bladder cancer in patients at risk for the disease. Unlike cystoscopy, CT urography can be used to evaluate the upper tracts concomitantly, which considered an important step in the evaluation of patients with bladder cancer.
In conclusion, the results of our study are encouraging and demonstrated that many causes of hematuria could be successfully detected with MDCT. Future efforts in continued refinement of MDCTU protocols must focus on radiation dose optimization and radiation dose reduction, which will likely be achieved by reducing the number of imaging phases and by using emerging technologies for radiation dose reduction. If efforts to optimize radiation dose results in acceptable radiation dosages comparable with IVU, MDCTU would appear to be the most likely imaging study to offer comprehensive ‘‘one-stop’’ imaging of the urinary tract.