الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 187 |  |  |
| | | from | 187 | | |
Abstract
Diseases of the stomach and duodenum are immensely common, accounting for 4% of family doctor visits per year and account for about 50% of cases of dyspepsia.
Gastric carcinoma represents the most common gastric neoplasm accounting for 95% of all gastric tumors.
Prognosis and therapy of gastric carcinoma depend on the stage of the disease at the time of the diagnosis and the first challenge for clinicians is to define the extent of the tumor in order to plan the best treatment Besides, an early diagnosis and accurate staging are crucial for the choice of an accurate therapeutic approach and can also influence the survival rate.
Endoscopy and double contrast barium examination of the upper gastrointestinal tract are still the basic investigational tool for diagnosing gastric malignancies, but they are stressful and uncomfort¬able for patients. Also, they are exclusively based on depiction of the gastric mucosa and are limited by their inability to evaluate transmural and extragastric exten¬sion of disease. This means that they are unsuitable for T as well as M-staging according to the TNM system.
The depth of mural invasion and the presence of extragastric lesions can be determined with endoscopic ultrasonography (US) and computed tomography (CT) which are often used as preoperative image modalities in staging gastric malignancies. EUS was superior to CT in T staging and perigastric lymph node evaluation in previous studies. However, it cannot be used for metasatatic staging (peritoneal dissemination and liver metastasis) due to diminution of the field of view.
Recently, fast scanning with rapid infu¬sion of IV contrast medium administration (dynamic CT) and filling the stomach with a large amount of low-density fluid have been used to overcome the limitations of conventional CT in the evaluation of the transmural and extraserosal spread of disease with rates of high accuracy rates.
The depth evaluation of gastric carcinoma mural invasion is improved with the clinical application of multidetector devices and multiplanar reconstructions. Therefore, multidetector computed tomography currently remains the most commonly used examination in the preoperative gastric cancer staging, with faster examination times and higher spatial resolution. In fact, it allows to acquire isotropic voxels and to reduce motion artifacts as compared to single-detector devices and the resulting benefits are represented by a better image quality in axial, coronal and sagittal planes and also better quality reconstructions as well as three-dimensional (3D) ”navi¬gator” virtual gastroscopic (VG) scanning of the gastric images , with an overall greater diagnostic accuracy.
Multidetector CT is the modality of choice for planning curative or palliative surgery and provides useful information for comparison during chemotherapy in patients with inoperable carcinomas .It accurately defines the group of patients for whom primary surgical therapy will not be suitable.
Therefore, preoperative staging of gastric cancer appears to be by far the main clinical indication.
In addition, multidetector CT plays an important role in evaluation of post operative complications and detection of tumor recurrence following partial gastrectomy.
Despite substantial advances introduced by MDCT technology, there are still several limitation. The main disadvantage is that they are time consuming. A second limitation is the inability to obtain histologic results. A third limitation is patient exposure to substantial doses of ionizing radiation. Also its inability to detect flat type of early gastric cancer (IIB) even in combination with VG and MPR images.