الفهرس 
Applied Anatomy of the Prostate GlandOnly 14 pages are availabe for public view
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Abstract
Cancer prostate is one of the most common malignancies in elderly men.
The diagnosis of cancer prostate is based mostly on the results of ultrasonography (US)- guided transrectal biopsy. Because of the low accuracy of US for cancer prostate detection and localization, a random biopsy is usually performed. However, it has several disadvantages. For example, it may lead to an increase in complications because of the unnecessary sampling of normal prostate tissue. Moreover, cancer located outside the routine biopsy site may be missed. In addition, there may be difficulty in determining the site of a previous biopsy when repeating biopsy in a patient with a previous negative result and continuously high prostate-specific antigen levels. For these reasons, an imaging modality is needed that allows the accurate detection and localization of cancer prostate , as well as local staging, guidance of biopsy, and adequate follow- up after treatment.
Although T2-weighted MR imaging has been used widely for the pretreatment work-up of cancer prostate on the basis of its excellent soft tissue resolution, but its accuracy for the detection and localization of cancer prostate is unsatisfactory as T2-weighted imaging has significant limitations for depicting cancer in the transitional and central zones, because cancer and normal tissues both have low signal intensity on T2-weighted images. In addition, low signal intensity may be seen in the peripheral zone on T2-weighted images in the presence of many noncancerous abnormal conditions, such as nonspecific inflammation, biopsy related hemorrhage, post–radiation therapy fibrosis, and changes after hormone deprivation therapy.
In order to improve the diagnostic performance of MRI, investigators have applied, dynamic contrast-enhanced (DCE) MRI, and MR spectroscopy (MRS) to cancer detection, staging, monitoring of treatment effect, and guidance from prostate biopsy. Recently, the majority of basic and clinical researches of cancer prostate are shifting to these functional MR imaging techniques.
Dynamic contrast enhanced MR imaging allows an assessment of parameters that are useful for differentiating cancer from normal tissue. The advantages of this technique include the direct depiction of tumor vascularity , DCE MRI is helpful for the detection and localization of cancer prostate moreover, DCE MRI has been shown to provide ahigh accuracy for determining the extracapsular extension of cancer prostate and detecting local recurrence after a radical prostatectomy.
However, there also are also disadvantages, such as limited visibility of cancer in the transitional zone. Another a disadvantage of DCE MRI is that there are too many parameters for observers to interpret and this limitation is prominent for differentiating cancer prostate from noncancerous transitional zone tissue. This overlap also decreases specificity for cancer detection.
MR spectroscopy, depicts a higher ratio of choline and creatine to citrate in cancerous tissue than in normal tissue. The technique also allows detection of cancer prostate in the transitional zone and can be used to predict the aggressiveness of cancer prostate, however, it requires a long acquisition time , does not directly depict the periprostatic area and frequently is affected by artifacts.
The combined use of MR imaging and MRS may be useful in evaluating low-risk cancer prostate . The combined use of T2WI and MRS was better at predicting the probability of cancer prostate .
Thus, a comprehensive evaluation in which both functional and anatomic MR imaging techniques are used with an understanding of their particular advantages and disadvantages may help improve the accuracy of MR for detection and localization of cancer prostate .
Integration of MRS into routine prostate MRI practice has improved tumor detection rates. Moreover, MRS has been used to help detect recurrence after therapy