Gastric Pathology: SDCT/MDCT of the Stomach

Karen M. Horton ,MD and Elliot K. Fishman, MD

INTRODUCTION

Although barium studies and endoscopy have classically been considered the diagnostic modalities of choice for the evaluation of gastric pathology, CT is increasingly used as the first line imaging study in patients with a variety of symptoms. It is imperative, therefore, that the radiologist be familiar with the CT appearance of the normal stomach as well as the appearance of a variety of gastric conditions. In addition, CT also plays an important role in the staging and follow-up of gastric malignancies, once the diagnosis has been established.

The recent technical advancement in CT along with current interest in the use of water and air contrast techniques, suggests that the usefulness of CT in the evaluation gastric pathology may increase.

TECHNIQUE

For adequate CT examination of the stomach, careful technique is essential. The key to CT imaging of the stomach is gastric distention, as wall thickening can be simulated by underdistension or pathology can be masked. Gastric distention can be accomplished by positive contrast solutions such as Hypaque (Amersham Health, Princeton, NJ), by neutral agents such as water or by negative contrast agents such as air.

positive contrast

Traditionally, for abdominal imaging, positive contrast agents such as Hypaque (Amersham Health, Princeton, NJ) have been utilized. 500-750 cc of a 3% oral Hypaque solution is routinely administered 30-60 minutes before the scan in order to fill the stomach and small bowel loops. An additional 250 cc of oral contrast is given immediately prior to scanning to insure maximal distention of the stomach.

Although widely used, there are some concerns that positive contrast agents may obscure pathology when the gastrointestinal wall is simultaneously enhanced with intravenous agents 1, 2. In addition, there are reports of inadequate mixing of these agents with gastrointestinal contents, sometimes resulting in "pseudotumors"3, 4. Finally, the use of positive oral contrast agents interferes with manipulation of the data set in CT angiography. Therefore investigators have explored the use of alternative oral contrast agents for use with abdominal CT.

water contrast

Several investigators have advocated the use of water as a low density contrast agent for imaging of the stomach and upper gastrointestinal tract 1, 5-8. Water is safe, well tolerated, and inexpensive. Water may allow better visualization of the enhanced wall of the stomach and small bowel and will not interfere with CT angiography, as has been described with positive contrast agents1, 2 (Figure1). Limitations of the use of water include: suboptimal evaluation of the distal small bowel and colon and potential confusion between water filled bowel loops and abnormal abdominal fluid collections (abscess). These theoretical concerns are not usually a problem when IV contrast is administered, because even nondistended bowel loops have a characteristic wall enhancement and fold pattern which allows identification. However, water would limit the ability to diagnosis extravasation of contrast from gastrointestinal perforation and therefore for this clinical indication, positive contrast agents are preferred5. Some authors have advocated giving positive contrast initially, followed by water9. The positive contrast will opacify the distal small bowel loops, while the water will distend the stomach and proximal small bowel.

We prefer to use water in patients with suspected gastric pathology. If water contrast is desired, 750 cc of water is given 20-30 min prior to the exam. An additional 250 cc of water is given to the patient immediately before scanning begins.

air contrast

If air contrast is desired, effervescent citrocarbonate granules (4-6g) can be given with 30 cc of water. Gaseous distention alone, while good for evaluation of stomach pathology, does not provide adequate contrast for the remainder of the bowel. Gas granules can also be administered after the patient has consumed the Hypaque or water for additional air distention of the stomach. Air, like water, is a negative contrast agent and therefore allows better visualization of bowel wall enhancement will not interfere with CT angiography.

Oil based agents have also been investigated as potential CT oral contrast agents10 and do allow adequate depiction of the gastric wall, but are not well tolerated by patients and typically will cause steatorrhea.

IV Contrast

Regardless of the oral contrast agent used, the administration of intravenous contrast is essential for complete evaluation of the stomach. Spiral CT and MDCT combine rapid scanning and rapid infusion of contrast resulting in better visualization of bowel loops and gastric wall. Often subtle changes are well visualized. Typically, 120 cc of Omnipaque 350 (Amersham Health, Princeton, NJ) is injected intravenously, at a rate of 2-3 cc/sec. Scanning begins approximately 45 second after the initiation of the contrast injection.

Scan Protocol

With a single detector row spiral scanner, 5mm collimation is adequate. A 3mm reconstruction interval is helpful if 3D imaging is to be performed. However, when imaging gastric pathology, we prefer to utilize our multidetector row scanner. It is faster, allows thinner collimation and has better resolution compared to traditional single detector row scanners. We currently use a Siemens Somatom Volume Zoom (Siemens Medical Solutions, Iselin, NJ) which can be 8 times faster than traditional 1 second single detector row spiral scanners. Depending on the collimator setting, the Volume Zoom can acquire up to 4 slices per 0.5 sec rotation. This almost eliminates motion artifacts. Also these scanners allow thinner slices than single detector spiral scanners. 1-1.25mm slices are easily obtainable. The thinner collimation definitely improves the quality of the 3D data set, in terms of gastric imaging as well as CT angiography.

When imaging a patient with gastric pathology, we utilize the 4 x 1.0 mm collimator setting; 1.25 mm slices are then generated. Using this setting, the abdomen (diaphragm to iliac crest ) can be scanned in 20 seconds. Depending of the indication, dual phase imaging may be performed. Arterial phase images are acquired 25 seconds after the start of the injection, venous phase images are acquired 50 seconds after the start of the injection. This allows optimal visualization of both the gastric arteries and veins as well as for optimizing detection of liver metastases.

3D Imaging

3D imaging of the gastrointestinal tract, the colon in particular, has gained much attention since it was first proposed in 1993. At that time, 3D imaging was limited by computer speed and performance. Early reports of 3D CT imaging of the stomach (CT gastroscopy) were limited to surface rendering techniques, i.e. shaded surface. However, with improvements in computer technology and speed, most manufacturers now also offer volume rendering. VR is superior to shaded surface for imaging the stomach and gastric vessels. We currently use the Siemens 3D Virtuoso Imaging package. This software includes real-time volume rendering as well as flythrough capabilities.

At our institution, after the data is acquired (1.25mm slices reconstructed at 1 mm intervals) it is transferred over an Ethernet to a Infinite Reality or Onyx workstation with Reality Engine graphics (Silicon Graphics, Mt. View, CA) or an O2 workstation for interactive volume rendering. Simple 2D multiplanar reconstructions of the CT data allow quick visualization of the stomach in the axial, sagittal and coronal planes (Figure 2). Most radiologists are familiar and comfortable with 2D MPR. It is quick and available on all workstations. An abnormality detected in one plane can immediately be visualized in the other two planes. It is often helpful to start with the MPR and then proceed with the 3D.

The 3D volume set can be manipulated using different orientations or cut planes in order to best demonstrate the stomach and pathology (Figure 3). This flexibility is a distinct advantage over traditional axial images. In addition to the use of cut-planes, the radiologist has the ability to change the opacity, brightness, window width and level. This allows the radiologist to accentuate certain structures.

In addition, the CT data of the stomach can be also be manipulated to simulate images as seen by the endoscopist for "virtual gastroscopy"4, 11, 12 (Figure 4). Early studies of this technique were limited, mostly due to computer limitations . In a study by Springer et al, of both cadavers and patients the endoluminal views using shaded surface display correlated well with endoscopy except for artificial smoothing of surface structures and density limitations created by the shaded surface technique4. The quality of virtual gastroscopy is improved with the use of the thinner collimation available on MDCT scanners and with the increase in the availability and speed of volume rendering. Often it is not necessary to fly through the stomach as is typically done with CT colonography, but instead, the radiologist can simply use the clip planes and different orientation planes to visualize the entire stomach11.

NORMAL STOMACH

The gastric fundus lies in the left upper quadrant of the abdomen. The gastroesophageal junction can be identified as a small soft tissue structure which indents the medial aspect of the cardia. The body of the stomach obliquely crosses the midline anteriorly and then curves posteriorly to become the antrum. The pylorus can be identified by its narrowed lumen, connecting the antrum to the duodenal bulb13.

Optimal distention of the stomach results in effacement of the normal folds (Figure 5). The normal gastric wall is very thin, usually measuring 5-7mm or less when the stomach is distended. Wall thickness greater than 8-10 mm is definitely abnormal. However, the wall of the fundus and antrum may appear thicker than the remainder of the stomach, due to their orientation within the scanning plane. This should not be confused with pathology at these sites.

The stomach is surrounded by perigastric fat, which should be of uniform density. Increased density in the perigastric fat or loss of fat planes between the stomach and adjacent organs indicates pathology.

With the use of faster scanners and bolus IV contrast, the normal wall of the gastrointestinal tract enhances brightly, up to 120 HU2. Therefore, with the use of water as oral contrast along with a good IV contrast bolus, the gastric wall is well visualized between the low density intraluminal water and the extragastric fat.

GASTRIC MALIGNANCY

Adenocarcinoma of the stomach

Adenocarcinoma represents approximately 95% of malignant gastric tumors. The incidence continues to decrease in the United States, with 22,800 new cases predicted to occur in the US each year 14. However, the prevalence of gastric carcinoma continues to be high in other countries such as Japan, Chile and Iceland. The five year survival rate is approximately 20%11, 15, 16.

Males are effected more commonly than females, with most patients presenting in the sixth decade. Several conditions have been identified which may predispose to the development of adenocarcinoma of the stomach including: pernicious anemia, gastric atrophy, Billroth II, achlorhydria and hypochlorhydria. In addition, dietary habits, geographic factors and race are also important17. In the last several years there has been much interest in exploring a possible relationship between Helicobacter pylori and gastric cancer 18. Further studies are need to fully understand H-pylori's role.

Staging

CT is the most frequently used imaging modality for staging adenocarcinoma of the stomach. However, its precise role remains controversial. Some surgeons recommend laparotomy in all cases of gastric cancer for either curative resection or palliation obviating the need for a CT scan. Conversely, many surgeons rely on CT findings to help stage the malignancy, plan patient therapy, and plan the surgical approach. The reported accuracy of CT in gastric cancer staging has varied widely in the literature, partially due to differences in scanning techniques over the past two decades. With the advent of Spiral CT and more recently MDCT, combining narrow collimation and close interspace scanning, it is very likely that the accuracy of CT will improve. In a study by Hori et al using SDCT of patients with advanced gastric cancers, water was used as an oral contrast agent. CT detected 95% of the advanced cacinomas and 93 % of the early carcinomas8. In a different study of gastric cancer staging at CT by Baert et al, CT was able to detect 22/24 cancers (91%)7. CT has some limitation when staging gastric cancers, as it cannot always determine the level of invasion within the gastric wall19. Endoscopic ultrasound is more sensitive for visualizing the individual gastric wall layers.

In addition to the use of water as oral contrast, there may be some benefit to performing dual phase imaging of the abdomen when staging patients with gastric carcinoma, as supported in studies by Hundt et al and Mani et al20, 21. Hundt et al performed dual phase imaging of the abdomen during the arterial and venous phases of enhancement and was able to detect 97.5% (39/40) cancers20. The CT staging correlated with the surgical and pathological staging in 79%. The major limitation to staging in that study was difficulty in detecting tumor invasion in normal sized lymph nodes.

Mani et al , also performed dual phase imaging, but at 45 s and 3 minutes after IV contrast injection21. The authors found that the 45s scan was helpful for determination of the depth of the tumor and invasion through the gastric wall and correctly determined the depth of tumor invasion in 17/20 patients21. The 3 min delay was not found to be helpful. It is not clear why the authors chose such as long scan delay, and decided not to image earlier, during the arterial phase which would be beneficial for displaying the arterial anatomy. The optimal protocol for imaging patients with gastric malignancies has not yet been determine. However, it is clear that a portal venous phase scan is necessary in order to detect potential liver metastases. The addition of arterial phase imaging may also be helpful in select cases.

In addition, 3D imaging may help improved the staging accuracy of CT. In a study by Lee et al of patients with advanced gastric cancer, the combination of 3D imaging with axial images allowed more accurate staging than with axial images alone16.

CT IMAGING

Primary Tumor

Common CT appearances of primary gastric carcinoma include discrete soft tissue mass with or without ulceration or wall thickening, which may be focal or diffuse (linitis plastica)14 (Figures 6, 7, 8). The average wall thickness in gastric carcinoma is 2 cm, ranging from 6 mm - 4.0 cm. Due to limited spatial resolution, CT is often not able to distinguish the layers within the gastric wall and is therefore not able to determine depth of tumor invasion. However, CT is able to accurately demonstrate wall thickening, which has been shown to correlate directly with probability of transmural extension. Patients with diffuse infiltration of the stomach can present with linitis plastica. In those cases the stomach will the thickening and will often allow only limited distention.

In a study by Cho et al, using water contrast, dynamic scanning, rapid intravenous contrast injection and dual phase image acquisition, 88% of the primary gastric cancers were detected. This detection rate could potentially improve if spiral scanning were utilized22. 3D imaging of the stomach may improve the rate of detection of tumor. In a study by Lee et al, of 31 patients with early gastric cancer, the investigators were able to detect 93.5% of the tumors when using 3D CT. Only 64.5% of the tumors were detected on axial images alone15.

Local Extension

Stage III tumors are characterized by extragastric extension of tumor with or without regional adenopathy (Figure 9). Early perigastric invasion may appear as increased attention of the fat surrounding the stomach, or obliteration of fat planes separating the stomach from adjacent organs (i.e.. pancreas). Although fat plane obliteration is a reliably sign of extragastric tumor invasion, the absence of distinct fat planes can occur as a normal variant in cachectic patients, or in patients with inflammatory conditions such as pancreatitis. The most problematic area for CT in staging gastric neoplasms, is in determining pancreatic invasion23, 24. This inability of CT to distinguish between fat plane obliteration due to inflammation from tumor, has limited CT usefulness in staging the primary tumor in earlier studies. 3D imaging which allows real-time manipulation of the data set, may help better visualize local extension of tumor and invasion of adjacent organs.

Adenopathy

The detection of adenopathy is important in evaluation of gastric carcinomas, as perigastric lymph node involvement decreases median survival by 65%25. Nodal spread of disease may extend into or around the gastrohepatic ligament (Figures 6 & 10). Nodes in this region are considered suspicious for harboring malignancy if they are greater than 8 mm in diameter 26. Although the best indication of lymph node involvement is enlargement, it has been shown that normal sized nodes may contain tumor, while some enlarged nodes do not. Multiple enlarged nodes are more likely to be malignant than a solitary enlarged node27. Other factors that may help distinguish metastatic from normal nodes is lack of enhancement .

The reported sensitivity of CT for detection on adenopathy in patients with adenocarcinoma of the stomach ranges between 47-97%23, 28, 29. Although, the use of spiral CT may help improve results, the major limitation is CT continues be its inability to detect microscopic involvement of normal sized nodes.

Distant Metastases

Spiral CT is excellent for the detection of distant metastases in patients with gastric cancer, as it combines rapid imaging, and intravenous contrast injection with three dimensional imaging display capabilities . Common sites for gastric metastatic disease include the liver, adrenal glands, and bone (Figure 9 & 10). In addition, gastric cancer can involve the ovaries (Krukenberg tumor). Gastric cancer may also be associated with carcinomatosis (Figure 11) .

Spiral scanning with rapid IV contrast injection is considered the preferred technique for liver imaging. A study of the detection of hepatic masses using single detector spiral CT demonstrated a better than 90% sensitivity for detecting lesions over 1cm in size, and a 56% sensitivity for detecting lesions less than one centimeter30. This is an improvement compared with traditional CT scanning and it is likely that these numbers will improve with the MDCT.

Postoperative Stomach and Recurrence

In patients with limited disease, partial gastrectomy is the treatment of choice. The median survival for patients after subtotal gastrectomy is 18 months, and after total gastrectomy only 12 months. The success of gastrectomy depends on the extent of gastric wall invasion and lymphatic spread. Chemoradiation protocols are being tested in an attempt to improve survival after gastrectomy. After treatment, these patients are followed regularly with endoscopy and CT in order to identify recurrence.

In a study by Ha et al of 36 patients with tumor recurrence s/p gastrectomy, 69% of recurrences involved nodal spread along the celiac axis or hepatic pedicle; 28% of recurrences involved the anastomotic site or gastric stump, 22% involved the pancreas and 11% occurred in the anterior abdominal wall31. A similar study by Mullin of 38 patients with recurrent tumor after gastrectomy for carcinoma also demonstrated that the majority of recurrence involved regional lymph nodes or metastases to organs such as the liver, lung, adrenals or bone32. Occasionally the recurrence can be extensive, involving peritoneal implants and carcinomatosis.

Endoscopic ultrasound, upper endoscopy, barium are often capable of detecting recurrence at the anastomosis or in the gastric stump, but are unable to image tumor spread to the abdominal wall or distant organs. In addition, CT is useful guide for percutaneous biopsy of suspicious lesions.

LYMPHOMA

Gastric lymphoma comprises approximately 1-5% of all gastric malignancies, and represents the most common extranodal site of non Hogkins lymphoma 33. The majority of cases are non Hodgkin's lymphomas, predominately of the diffuse histiocytic subtype. The CT appearance of gastric lymphoma is variable. Gastric lymphoma may appear as diffuse or segmental wall thickening , with an average wall thickness of 4-5cm33, 34. Alternately gastric lymphoma may present as a localized polypoid mass with or without ulceration14. Most patients with gastric lymphoma have associated adenopathy, which is often bulky and may extend below the left renal hilum.

The CT appearance of gastric lymphoma may mimic adenocarcinoma of the stomach (Figure 12, 13). Several key finding have been identified which may help distinguish the two malignancies. First, the gastric wall in lymphoma tends to be thicker (4-5cm) and more lobular than in adenocarcinoma (1-3cm). In addition, although lymphadenopathy may occur in both gastric lymphoma and adenocarcinoma, adenopathy in gastric lymphoma tends to be bulkier and often extended below the level of the renal hilum. Finally, although gastric lymphomas may appear as large bulky tumors, they are often pliable and rarely result in gastric outlet obstruction13.

Spiral CT is valuable for both patients with primary gastric lymphoma and in detecting gastric involvement in patients with more extensive disease. Accurate staging of disease is enhanced with narrower scan collimation and interscan gaps. Water as oral contrast may also be helpful in identifying more subtle cases. In addition, it is necessary to optimize organ enhancement and disease detection in the liver, spleen and kidneys. Solid organ involvement is being detected more commonly especially in patients whose lymphoma is a result of immunosuppression, be it due to AIDS or following organ transplantation. With the increase use of CT we are seeing cases of incidental gastric lymphoma. These cases are uncommon but we are able to be identified especially if careful attention to paid to scan protocols.

Mucosa-associated lymphoid tissue (MALT) lymphoma is a low grade lymphoma which is being recognized with increased frequency. It is thought to be associated with Helicobacter pylori. This tumors differ from the typically high grade Non-Hodgkin gastric lymphoma. In a series of 40 patients with gastric MALT lymphoma by Kessar et al, the most frequent finding was gastric wall thickening35.The wall thickening is usually minimal and my not be detected on CT, especially is the stomach is not maximally distended (Figure 14). Associated adenopathy or extragastric distention is not common35.

Treatment consists of surgery with postoperative chemoradiation therapy. Radiotherapy alone may be effective in patients with stage I and II disease. Chemotherapy is indicated in patients with disseminated disease.

Gastrointestinal Stomal Tumors

Gastrointestinal stromal tumors are gastrointestinal neoplasms which arise from mesenchymal cells in the bowel wall. These tumors which were formerly referred to as smooth muscle tumors such as leiomyomas or leiomyosarcomas, have undergone pathological reclassification. These tumors encompass several different histological varieties which demonstrate variability in differentiation and are categorized based on immunohistiochemical and ultrastructural studies36. Stromal tumors can be classified histiologically as myogenic (arising from smooth muscle), neurogenic (arising from neural elements) or less differentiated tumors, referred to as GIST. Stromal tumors with smooth muscle differentiation were formerly called leiomyoma/leiomyosarcoma. They account for only 1% of gastric tumors, and usually occur in adults37.

On CT, these tumors vary in appearance and size. 90% of gastric leiomyosarcomas occur in the fundus or body of the stomach38. Small tumors will appear as masses arising from the smooth muscle layers of the bowel wall (Figure 15). As the tumors grow, they stretch the overlying mucosa and can ulcerate. When large (>5cm), the tumors often appear grow exophytic and may contain areas of central necrosis or calcification39. When the tumors are large and exophytic it may be difficult to appreciate their gastric origin on axial scans (Figure 16). Multiplanar reconstructions and 3D imaging can be helpful to better characterize the mass and its relationship to the stomach. Adenopathy is uncommon, unlike patients with gastric adenocarcinoma or lymphoma.

CT cannot usually differentiate between malignant and benign gastric stromal tumor unless obvious local invasion or metastatic disease is detected37. However, small tumors (<4-5cm) are usually benign. Malignant stromal tumors can invade adjacent organs and can metastasize hematogenously, usually to the lung or liver or peritoneal surfaces39. Metastatic lesions may also appear cystic due to central necrosis. It is important to careful investigate all cystic lesions in the liver in patients with gastrointestinal stromal tumor, as the cystic metastases can mimic benign liver cysts.

METASTASES

Metastases to the stomach occur in approximately 2% of patients who die of cancer each year. Metastases which involve the stomach by hematogenous spread include melanoma, breast and lung, ovary (Figure 18 & 19) . Cancers of the esophagus and colon can spread to the stomach by lymphatic invasion. The stomach by also be involved by direct extension of local malignancies originating in the colon, pancreas or liver40, 41. Patients can present with a variety of symptoms including gastrointestinal bleeding, anemia, epigastric pain, gastric outlet obstruction.

The CT appearance of metastatic disease of the stomach is variable. It can appear as a solitary mass, multiple masses (melanoma) or as rigid wall thickening , as in linitis plastica (breast). The appearance of metastatic disease can be indistinguishable from primary gastric malignancies, stressing the importance of clinical information27. Tumor implants on the stomach are especially common in processes such as ovarian cancer.

GASTRIC VARICES

Gastric varices are tortuous distended collateral vessels fed mainly from the coronary vein which may develop in association with esophageal varices in patients with cirrhosis and portal hypertension. While intra or extrahepatic obstruction leads to esophageal and gastric varices, isolated splenic vein occlusion leads to the development of gastric varices, without accompanying esophageal collaterals. Gastric varices may occur in any region of the stomach, but are most commonly located in the fundus. Although gastric varices do not bleed as frequently as esophageal varices, hemorrhage from gastric collaterals can be more severe.

The ability of endoscopic and the conventional esophagogram to diagnosis gastric varices is limited, especially if not accompanied by esophageal varices. In the past angiography was considered the most reliable method for diagnosis of gastric varices. With the advent of CT, CT with intravenous contrast was quickly shown to be a sensitive method for the detection of gastric varices42. In recent years, spiral CT with intravenous contrast has been shown to be an accurate modality for the detection and evaluation of portosystemic shunts in patients with portal hypertension43.

The CT appearance of gastric varices varies depending on the size and extent of involvement. Usually, on unenhanced scans, gastric varices appear as a scalloped, lobulated gastric border .With IV contrast, gastric varices will appear as enhancing tubular and rounded structures within in the gastric wall. On noncontrast scans, large varices can simulate adenopathy in the posterior mediastinum which is a potential pitfall13, 14.

CT Angiography with volume rendering and 3D image display can also be used to better evaluate gastric varices and their relationship to the portal and systemic venous systems44 (Figure 20).

GASTRITIS

There are many causes of gastritis including infections (Helicobacter pylori, Cryptosporidia, CMV), inflammatory conditions (Crohn disease, eosinophilic gastroenteritis, Zollinger-Ellison syndrome), radiation and ingestion of alcohol, corrosive agents, or drugs.

At CT, gastritis usually appears as gastric fold and wall thickening, regardless of etiology. The thickened wall typically has soft tissue density. Although, if there is significant edema, the wall may a have a low density14 (Figure 21). In some patients, a due to significant edema and hyperemia, a layered appearance can be seen in the gastric wall after intravenous contrast. This will be most apparent on early phase imaging and helps to confirm the diagnosis, as neoplasms of the stomach will not respect the bowel wall layers and typically will not result in this layered appearance. Gastritis does not have to involve the stomach diffusely and thus can appear as focal or segmental thickening (Figure 22). Helicobacter pylori gastritis in particular can simulate a gastric neoplasm, as it often results in circumferential antral wall thickening or focal thickening along the greater curvature45.

Adequate gastric distention is necessary in order to avoided confusing wall thickening from gastritis with underdistention. The CT appearance of gastritis and gastric cancer often overlap, requiring biopsy for the definitive diagnosis.

CONCLUSION

Although CT is not the primary imaging modality for gastric disease, it plays a significant role in the evaluation and staging of gastric carcinoma and in the imaging of a variety of benign diseases. With the increased use of water as an oral contrast agent along with the introduction of multidetector row CT and continued advancements in 3D volume rendering, the role of CT in the evaluation of gastric diseases continues to evolve.

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