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Imaging Findings of Gastric Carcinoma

Written By

Eriko Maeda, Masaaki Akahane, Kuni Ohtomo, Keisuke Matsuzaka and Masashi Fukayama

Submitted: 26 July 2012 Published: 23 January 2013

DOI: 10.5772/52076

From the Edited Volume

Gastric Carcinoma - New Insights into Current Management

Edited by Daniela Laz?r

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1. Introduction

Surgery is the only certain treatment for gastric carcinoma, so early detection and accurate staging is a key to successive treatment and mortality reduction. In this chapter, we would like to explain radiologic imaging of gastric carcinoma by

  1. Reviewing the evidences for gastric carcinoma screening

  2. Demonstrating the TNM classification of gastric carcinoma and the relevant imaging findings for each stages and

  3. Introducing unusual imaging findings of gastric carcinoma and differential diagnoses.

1.1. Gastric carcinoma screening

Gastric carcinoma is the fourth most common cancer worldwide, behind lung, breast and colorectal carcinomas, and is the second leading cause of death in both sexes worldwide and in Asia [1, 2]. There is about twice male predominance.Gastric carcinoma is particularly common in countries such as Korea (incidence 62.2 per 100,000 males; mortality 22.8 per 100,000 males), Japan (46.8; 20.5), China (41.3; 30.5), Chile (27.3; 23.1), Russia (26.9; 24.0) but not as common in a large part of western societies such as the United States (5.7; 2.7) and United Kingdom (8.0; 4.8) [1].

The high mortality is mainly due to late presentation, therefore early detection and treatment is an important way to reduce death from gastric cancer [2].There are four major methods for screening gastric carcinoma; fluoroscopy, endoscopy, serum pepsinogen testing, and Helicobacter pylori antibody testing [3]. Because of a large difference in burden of gastric carcinoma among nations, benefit of gastric cancer screening cannot be debated on the same ground for societies throughout the world. However, there have been no randomized trials evaluating the impact of screening on mortality from gastric carcinoma [2,3].For societies where gastric carcinoma is uncommon, National Cancer Institute of the United States state that for screening would not result in a decrease in mortality fromgastric carcinoma [4].

In Japan, there is a government-sponsored mass screening program with barium meal fluorography. Participants are recommended to undergo endoscopy of the upper gastrointestinal tract when positive findings are detected at fluorography. Asymptomatic individuals older than 40 years are eligible for this program, but only around 20% of the eligible subjects actually participates the program [3]. Most case-control studies from Japan show a 40-60% decrease in mortality from gastric carcinoma in the subjects who participated the program [2,5-8]. In contrast, Japanese prospective series setting death from gastric cancer as an endpoint have inconsistent results [2,9-13].Even in combination with serum pepsinogen, a large Japanese study screening 17,647 men aged 40-60 years the positive predictive value over the 7-year period was 0.85% [14].Thus even in societies with high incidence, identification of high-risk groups that benefit from screening may be necessary to perform cost-effective screening.The subgroups might include elderly patients with atrophic gastritis or pernicious anemia, patients with partial gastrectomy, patients with Epstein-Barr virus associated gastric carcinoma or history of multiple carcinomas, patients with the diagnosis of sporadic adenomas, familial adenomatous polyposis or hereditary nonpolyposis colon cancer [15-19].

Endoscopy has advantage over fluoroscopy, especially in detection of flat and non-ulcerative lesions. A Japanese study comparing finding ratio of gastric carcinoma with fluoroscopy and endoscopy reports 2.7 to 4.6-times higher ratio for endoscopy [20]. However, effective screening with endoscopy relies on the skill of the endoscopists and availability of endoscopes, and it is likely to be unfeasible to perform mass screening using endoscopy.

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2. TNM classification of gastric carcinomas and the relevant imaging findings

Owing to recent advances in CT technology, we have been able to visualize early carcinomas and to stage tumors with considerable accuracy, with the use of appropriate contrast technique and effervescent agent or water [21]. Recent CT with conventional transverse images, multiplanar reconstruction (MPR) images and virtual endoscopy can detect gastric carcinomas efficiently with the detection rates of 91%, 96% and 98%, respectively [22].

Gastric carcinomas appear as a focal area of mural thickening with or without ulceration, as a polypoid lesion, or as generalized mural thickening. Lesions occurring in the antrum, in the body, and in the fundus comprise 30% of all gastric carcinomas respectively, and the remaining 10% involve the whole stomach [23].

CT criteria for T staging of gastric carcinoma is as follows [22].

T1 lesion = focal thickening of the inner layer, almost well enhanced, and has visible low-attenuation-strip outer layer of gastric wall and clear fat plane around tumor

T2 lesion = focal or diffuse thickening of the wall with transmural enhancement, almost well enhanced, and has smooth outer wall border and clear fat plane around tumor

T3 lesion = transmural tumor with irregular or nodular outer border and/or perigastric fat infiltration

T4 lesion = Obliteration of fat plane betweengastric tumor and adjacent organ or invasion of adjacent organ

Figure 1.

T1a gastric carcinoma in a 76-year old man. Contrast CT shows a subtle thickening and enhancement of the inner layer (arrow) with low-attenuation-strip outer layer of gastric wall and clear fat plane around tumor.

Figure 2.

T2 gastric carcinoma in a 82-year old man. Contrast CT shows a well-enhanced focal mural thickening (arrow)andfocal enhancement of the outer layer (arrowhead).The tumor has smooth outer wall border and clear fat plane around tumor.

Accuracy of CT in T-staging with transverse images only is 73%, but it rises to 89% with the use of MPR [22]. Therefore it is important to perform appropriate reconstruction techniques in CT diagnosis of gastric carcinoma.

Figure 3.

T3 gastric carcinoma in a 64-year old woman. Contrast CT shows a mass in the lesser curvature (arrow), obliterating the outer layer of the stomach. The outer border of the tumor is irregular, and perigastric fat stranding is visualized (arrowhead).

Figure 4.

Type IV gastric carcinoma in a 47-yer old man. Contrast CT shows diffuse mural thickening obliterating thefolds and the inner structure of the gastric wall (arrows). The enhancement “running” through the gastric wall is characteristic of scirrhous tumors.

T1 tumors are classified into T1a and T1b tumors; a T1a lesion stay within the mucosal layer, while a T1b lesion stay within the submucosal layer (Figure 1).

A T2 tumor infiltrates into the muscularis propria layer and stays within the layer (Figure 2).

A T3 tumor extends over the muscularis propria layer, but its border stays within the subserosal layer (Figure 3).

Figure 5.

Advanced gastric carcinoma in a 60-year old man. Contrast CT shows diffuse mural thickening of the antrum (arrows). The fat plane between the tumor and the liver is obliterated. Liver metastasis can be found as well (curved arrow).

Figure 6.

Advanced gastric carcinoma in a 60-year old man (the same patient as Figure 5). The clear and smooth border between the tumor and the liver (between two arrows) can be shown with coronal MPR. This tumor can be staged as T4a.

T4 tumors are classified into T4a and T4b tumors; A T4a lesion invades the serosa, exposing its surface to the peritoneal cavity in many cases. The tumor is classified as T4b when it invades the adjacent organs, such as the transverse colon, pancreas, spleen, liver and the diaphragm.Signet-ring cell carcinoma, often found at T4a stage, usually manifests as a scirrhous tumor, and appears as diffuse thickening of the gastric wall with obliteration of gastric folds, usually extending from the antrum into the body and fundus (Figure 4) [23].

T4b tumor requires resection of adjacent organs with the primary tumor, and discrimination of T4a tumors from “T4b-looking tumor” is an important function of preoperative imaging. An advanced tumor can be recognized as T4a when the fat plane between the tumor and the adjacent organ is visualized, or when the fat plane is invisible or compressed by the tumor, the tumor is considered to be T4a if it has a clear and smooth border (Figures 5-7).MPR in appropriate plane is especially effective in differentiating between T4a and T4b; MPR is reported to improve the specificity without compensation in sensitivity in diagnosis of invasion into the transverse colon or mesocolon and the pancreas [24].

Figure 7.

Advanced gastric carcinoma in a 88-year old woman. The tumor extends downwards toward the pancreas (arrow), and causes dilatation of the main pancreatic duct as a result of pancreatic infiltration (arrowheads). This tumor is staged as T4b.

Criteria for N staging for gastric carcinoma is as follows:

N0 = no lymph nodes involved

N1 = metastases in 1-2 regional lymph nodes

N2 = metastases in 3-6 regional lymph nodes

N3a = metastases in 7-15 regional lymph nodes

N3b = metastases in more than 15 regional lymph nodes

Gastric carcinoma is often accompanied with nodal metastases even at relatively earlier stages. Micrometastases and normal-sized metastatic nodes are common in gastric carcinoma, and this makes accurate N staging difficult. Ring enhancement,inhomogeneous enhancementand strong enhancement at arterial phase are known as possible signs of metastases in a normal sized lymph node. Therefore it is important to point out nodes with these atypical findings, even when the node is smaller than 10mm.Since accurate counting of lymph node metastases is the key to accurate N staging,active reconstruction with MPR is warranted for accurate measurement and interpretation of conglomerated lymph nodes (Figures 8,9).

Figure 8.

A 50-year old man with gastric carcinoma. Contrast CT shows a mass at the lesser curvature (arrow).

Figure 9.

A 50-year old man with gastric carcinoma (the same patient as Figure 8). MPR in the coronal plane shows this mass consists of two lymph nodes.

The liver is the most common metastatic sites for gastric carcinoma because the gastric veins drain into the hepatic portal system.Metastatic hepatic tumors are often accompanied with ring enhancement at earlier phase, and portal phase in addition to the equilibrium phase. Some tumors lose contrast to the liver parenchyma after the delivery of the contrast material, and we obtain the plane CT images as well in the metastasis survey protocolof our institution.Other common sites for distant metastases include the lungs, adrenal glands, and the ovaries (Krukenberg tumors).Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) is not appropriated for local tumor staging, but is effective for detection of distant metastases [25].

CT does not have enough sensitivity for detection of peritoneal dissemination. Even with recent 16- or 64-row detector scanners, the sensitivity and specificity of CT diagnosis of peritoneal dissemination are 28.3% and 98.9% respectively when definite criteria are adopted, and 50.9% and 96.2% when the criteria included the suspicious findings [26]. This report mentions greater tumor size and advanced T stage as predictive factors for dissemination, and recommends staging laparoscopy for tumors with these factors, even when CT results are negative for peritoneal dissemination. The value of FDG-PET in detection of peritoneal dissemination is still controversial [25].

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3. Unusual imaging findings of gastric carcinoma and differential diagnoses

Rarely, gastric carcinomas present with gross or psammomatous calcifications. Calcified gastric carcinomas are usually found in mucinous adenocarcinoma; a carcinoma characterized by prominent glandular formations and abundant mucin deposition. Calcifications in mucinous carcinoma are military and punctate [27,28]. Rarely, calcification within gastric carcinoma lesion occurs as a result of secretion of parathyroid hormone-like substance [29]. Other reported atypical features of gastric carcinomas include transpyloric spread, giant gastric folds and hypervascular masses [27,30,31].

Epstein-Barr virus associated gastric carcinoma (EBVaGC) is a clinicopathologically and molecularly distinct type of gastric carcinoma.EBV-associated gastric carcinoma (EBVaGC) occurs worldwide, with the reported incidence varying from 1.3% to 20.1%, affects 70,000-80,000 people per year (estimate), constituting the largest group of EBV-associated malignancies [16,32,33].EBVaGC is associated with male predominance, location in the proximal stomach, multiplicity and carcinomas affecting remnant stomachs [33,34].Although there are some conflicting evidences, lower rate of lymph node involvement and relatively favorable prognosis is suggested [32,33,35].EBVaGC is associated with two types of histology: lymphoepithelioma (LE) -like type which is almost identical to the subgroup reported as “gastric carcinoma with lymphoid stroma (GCLS)”, and ordinary type [36,37].Imaging findings of LE-like type or GCLS is characterized by a large thickness-to-length ratio, and is sometimes accompanied with a bulky portion projecting from the gastric wall [38] (Figure 10).

Figure 10.

LE-type EBVaGC in a 69-year old woman. Contrast CT shows massive mural thickening involving the gastric fundus and the esophagogastric junction (arrows).

Gastric carcinoma need to be differentiated from other malignant tumors involvingthe stomach, whichincludes carcinoid, carcinosarcoma, lymphoma, mucosa-associated lymphoid tissue lymphoma (MALToma) and gastrointestinal stromal tumor (GIST) (Figures 11-13) [27]. Benign tumors of the stomach include hyperplastic or adenomatous polyps, leiomyoma, schwannoma, lipoma, hemangioma and glomus tumor. Heterotopic pancreas can also be mistaken as a gastric carcinoma (Figure 14).

Figure 11.

Diffuse large B-cell lymphoma in a 73-year old woman. Contrast CT shows a dumbbell-shaped mass extending from the fundus into the spleen (arrow).

Figure 12.

High-grade GIST in a 53-year old man. Contrast CT shows an enormous tumor extending along the outer gastric wall (arrows).The tumor has a smooth border but the enhancement is very heterogeneous, with a large area of necrosis showing homogeneous low attenuation. Note the compressed cavity of the stomach (arrowhead).

Figure 13.

Low-grade GIST in a 74-year old man. Contrast CT shows a smooth round tumor with homogeneous enhancement within the fundus (arrow).

Figure 14.

A 46-year old woman with a submucosal mass. Contrast CT shows a mass (arrow) presenting similar enhancement as the pancreas (arrowhead). Heterotopic pancreas was suspected on CT and at endoscopic ultrasonography, and was confirmed by fine-needle biopsy.

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4. Conclusion

Although early detection is the key to the mortality reduction of gastric carcinoma, the benefit of screening is still under debate even in the societies with high incidence. Recent CT with appropriate reconstruction technique can detect and locally stage gastric carcinomas sufficiently. It remains a challenge to accurately diagnose lymph node metastasis and peritoneal dissemination with imaging. Imaging can also depict unusual manifestationsof gastric carcinomas such as calcification and a large thickness-to-width ratio or projecting mass in EBVaGC.

References

  1. 1. Ferlay J. Shin H.R. Bray F. Forman D. Mathers C. Parkin D.M. 2008 GLOBOCAN v1.2, Cancer Incidence and Mortality Worldwide: IARC Cancer Base No.10Lyon, France: International Agency for Research on Cancer
  2. 2. Leung W. K. Wu M. S. Kakugawa Y. et al. 2008 Asia Pacific Working Group on Gastric Cancer. Screening for gastric cancer in Asia: current evidenceand practice. Lancet Oncol. 9 3 279 87
  3. 3. Hamashima C. Shibuya D. Yamazaki H. et al. 2008 The Japanese guidelines for gastric cancer screening. Jpn J Clin Oncol. 38 4 259 67
  4. 4. National Cancer Institute 2012 Stomach (Gastric) cancer screening (PDQ) cancer. Health Professional http://cancer.gov/cancertopics/pdq/screening/gastric/
  5. 5. Kunisaki C. Ishino J. Nakajima S. et al. 2006 Outcomes of mass screening for gastric carcinoma. Ann Surg Oncol 13 2 221 28
  6. 6. Oshima A. Hirata N. Ubukata T. et al. 1986 Evaluation of a mass screening program for stomach cancer with a case-control study design. Int J Cancer 38 6 829 33
  7. 7. Fukao A. Tsubono Y. Tsuji I. et al. 1995 The evaluation of screening for gastric cancer in Miyagi Prefecture, Japan: a population-based case-control study. Int L Cancer 60 1 45 48
  8. 8. Abe Y. Mitsushima T. Nagatani K. et al. 1995 Epidemiological evaluation of the protective effect for dying of stomach cancer by screening programme for stomach cancer with applying a method of case-control study-a study of an efficient screening programme for stomach cancer. Nippon Shokakibyo Gakkai Zasshi 92 5 836 45
  9. 9. Oshima A. Hanai A. Fujimoto I. 1979 Evaluation of a mass screening program for stomach cancer. Natl Cancer Inst Monogr. 53 181 86
  10. 10. Hisamichi S. Sugawara N. 1984 Mass screening for gastric cancer by X-ray examination. Jpn J Clin Oncol. 14 2 211 13
  11. 11. Inaba S. Hirayama H. Nagata C. et al. 1999 Evaluation of a screening program on reduction of gastric cancer mortality in Japan: preliminary results from a cohort study. Prev Med. 20 2 9 102
  12. 12. Mizoue T. Yoshimura T. Tokui N. et al. 2003 Prospective study of screening for stomach cancer in Japan. Int J Cancer: 106 1 103 07
  13. 13. Lee K. J. Inoue M. Otani T. et al. 2006 Gastric cancer screening and subsequent risk of gastric cancer: a large-scale population-based cohort study, with a 13-year follow up in Japan. Int J Cancer 118 9 2315 21
  14. 14. Ohata H. Oka M. Yanaoka K. et al. 2005 Gastric cancer screening of a high-risk population in Japan using serum pepsinogen an barium digital radiography. Cancer Sci. 96 10 713 20
  15. 15. Staël von. Holstein C. Eriksson S. Huldt B. et al. 1991 Endoscopic screening during 17 years for gastric stump carcinoma. A prospective clinical trial. Scand J Gastroenterol 26 10 1020 6
  16. 16. Fukayama M. 2010 Epstein-Barr virus and gastric carcinoma, Pathol Int. 60 5 337 50
  17. 17. Ming S. Goldman H. 1965 Gastric polyps: a histogenetic classification and its relation to carcinoma. Cancer 18 6 721 726
  18. 18. Utsunomiya J. Maki T. Iwama T. et al. 1974 Gastric lesion of familial polyposis coli. Cancer 34 3 745 54
  19. 19. Aarnio M. Salovaara R. Aaltonen L. A. et al. 1997 Features of gastric cancer in hereditary non-polyposis colorectal cancer syndrome. Int J Cancer 74 5 551 5
  20. 20. Tashiro A. Sano M. Kinameri K. et al. 2006 Comparing mass screening techniques for gastric cancer in Japan. World J Gastroenterol 12 30 4874 75
  21. 21. Shimizu K. Ito K. Matsunaga N. et al. 2005 Diagnosis of gastric cancer with MDCT using the water-filling method and multiplanar reconstruction: CT-histologic correlation. AJR Am J Roentgenol 185 5 1152 58
  22. 22. Chen C. Y. Hsu J. S. Wu D. C. et al. 2007 Gastric cancer: preoperative local staging with 3D multi-detector row CT: correlation with surgical and histopathologic results. Radiology 242 2 472 82
  23. 23. Ba-Ssalamah A. Prokop M. Uffmann M. et al. 2003 Dedicated multidetector CT of the stomach: spectrum of diseases. Radio Graphics 23 3 625 644
  24. 24. Kim Y. H. Lee K. H. Park S. H. et al. 2009 Staging of T3 and T4 gastric carcinoma with multidetector CT: added value of multiplanar reformation for prediction of adjacent organ invasion. Radiology 250 3 767 775
  25. 25. Lim J. S. Yun M. J. Kim M. J. et al. 2006 CT and PET in stomach cancer: preoperative staging and monitoring of response to therapy. Radio Graphics 26(1) 143 156
  26. 26. Kim S. J. Kim H. H. Kim Y. H. et al. 2009 Peritoneal metastasis: detection with 16- or 64-detector row CT in patients undergoing surgery for gastric cancer. Radiology 253 2 407 415
  27. 27. Park S. H. Han J. K. Kim T. K. et al. 1999 Unusual gastric tumors: radiologic-pathologic correlation. Radio Graphics 19 6 1435 1446
  28. 28. Dickson A. M. Schuss A. Goyal A. et al. 2004 Radiology-Pathology Conference:Calcified untreated gastric cancer. Clin Imaging 28 6 418 21
  29. 29. Murayama H. Kamio A. Imai T. et al. 1982 Gastric carcinoma with psammomatous calcification: report of a case, with reference to calcinogenesis. Cancer 49 4 788 96
  30. 30. Mei M. Jingmei N. Zongming C. et al. 2012 Diffuse type gastric carcinoma presenting as giant gastric folds: Lessons learned from six miss diagnosed cases. Clin Res Hepatol Gastroenterol http://dx.doi.org/10.1016/j.clinre,2012.04.009
  31. 31. Johnson P. T. Horton K. M. Fishman E. K. 2010 Hypervascular gastric masses: CT findings and clinical correlates. AJR Am J Roentgenol 2010 Dec. 195(6):W 415 20
  32. 32. van Beek J. zur Hausen A. Klein Kranenbarg E. et al. 2004 EBV-positive gastric adenocarcinomas: a distinct clinicopathologic entity with a low frequency of lymph node involvement, J Clin Oncol. 22 4 664 70
  33. 33. Lee J. H. Kim S. H. Han S. H. et al. 2009 Clinicopathological and molecular characteristics of Epstein-Barr virus-associated gastric carcinoma: a meta-analysis, J Gastroenterol Hepatol 24 3 354 65
  34. 34. Murphy G. Pfeiffer R. Camargo M. C. et al. 2009 Meta-analysis shows that prevalence of Epstein-Barr virus-positive gastric cancer differs based on sex and anatomic location, Gastroenterology 137 3 824 33
  35. 35. Tokunaga M. Land C. E. 1998 Epstein-Barr virus involvement in gastric cancer: biomarker for lymph node metastasis, Cancer Epidemiol Biomarkers Prev. 7 5 449 50
  36. 36. Fukayama M. Ushiku T. 2011 Epstein-Barr virus-associated gastric carcinoma, Pathol Res Pract. 207 9 529 37
  37. 37. Watanabe H. Enjoji M. Imai T. 1976 Gastric carcinoma with lymphoid stroma. Its morphologic characteristics and prognostic correlations, Cancer 38 1 232 43
  38. 38. Maeda E. Akahane M. Uozaki H. et al. 2009 CT appearance of Epstein-Barr virus-associated gastric carcinoma, Abdom Imaging 34 5 618 25
  39. 39. Randjelovic T. Filipovic B. Babic D. et al. 2007 Carcinosarcoma of the stomach: a case report and review of the literature. World J Gastroenterol 13 41 5533 6

Written By

Eriko Maeda, Masaaki Akahane, Kuni Ohtomo, Keisuke Matsuzaka and Masashi Fukayama

Submitted: 26 July 2012 Published: 23 January 2013