| Objective:The aim of this study was to discuss the value of 18F-FDG PET/CT in differential diagnosis of gastric carcinoma and gastric lymphoma.Methods:We analyzed PET/CT scans of 80 gastric carcinoma(60 non-mucinous adenocarcinoma, 20 mucinous adenocarcinoma) and 47 PGL(22 mucosa-associated lymphoid tissue, lymphoma and 25 diffuse large B-cell lymphoma, DLBCL) from June 2006 to May 2014. We performed the spiral CT scanning followed by PET acquisition. And then we used the ANOVA test for the maximal gastrointestinal wall thickness(THKmax), the maximum standardized uptake value(SUVmax) of primary lesions and the CT value of the lesion, and we use SNK method on the comparison of SUVmax between the two groups; and use chis-quare test on the involvement of gastric tissue, the type of lesion gastric wall, mucosal morphology; and use Pearon analyze on the values of THKmax and the values of SUVmax. When analyzing lymph node metastases and splenomegaly, the sample is divided into two categories of PGL and gastric carcinoma and using chis-quare test on them.Results:PET-CT for gastric carcinoma and PGL can be expressed in different forms of thickening of the gastric wall, and most of gastric carcinoma expressed with segmental or localized thickening of the gastric wall, while most of the PGL expressed with diffuse or segmental thickening of the gastric wall. There were 8 cases of TypeⅠ(diffuse thickened gastric wall),8 cases of typeⅡ(segmental thickened gastric wall),6 cases of type Ⅲ(local thickened gastric wall) among 22 patients of MALT. And there were 13 cases of TypeⅠ, 7 cases of type Ⅱ, 5 cases of type Ⅲ among 25 patients of DLBCL. And there were 12 cases of TypeⅠ, 21 cases of type Ⅱ, 27 cases of type Ⅲ among 60 patients of non mucinous adenocarcinoma. The difference between the type of lesion of 4 kinds of patients were statistically significant(F=14.849,P<0.05).There were 16 cases of involving the retroperitoneal renal hilar lymph node and 7 cases with splenomegaly from gastric carcinomapatients, and the number of PGL patients were 10 and 12. There were 50 cases without lymph node metastases, 16 cases with unilateral mediastinal lymph node, 14 cases with bilateral mediastinal lymph node from gastric carcinoma patients. And the number of PGL patients were 26, 12, 9. The PGL patients are more likely to show up with splenomegaly than gastric carcinoma patients and the difference between then were statistically significant(P<0.05)。There is no statistically significant difference between PGL and gastric carcinoma patients in lymph node metastases(P >0.05).Among 80 gastric carcinoma patients, there was only one case of mucinous adenocarcinoma showed negative FDG with T3 step, while other 79 cases showed positive FDG. Among 47 PGL patients, there was only one case of MALT showed negative FDG with I step, while other 46 cases showed positive FDG. The CT values of this 4 kinds of patients are 41±11HU、38±9HU、40±11HU、40±8HU, and the SUVmax value are 4.6±2.9、18.3±7.6、5.6±1.9、9.9±6.6, and the THKmax values are 1.3±1.1cm、2.6±1.5cm、1.9±0.9cm、2.1±1.2cm.The type of lesion and SUVmax of four groups of patients were statistically significant difference(F=26.922,P<0.05),with compare of any pair of them: there was no statistically significant difference between MALT and mucinous adenocarcinoma(P>0.05),and for other compare, there was statistically significant difference(P<0.05). The difference between the CT values and the THKmax values of the 4 kinds of patients were no statistically significant(P>0.05). The SUVmax values of the above 4 kinds of patients were unrelated to there THKmax values(R=0.055, 0.346,0.226,0.133,P > 0.05). The number of cardiac involvement patients of MALT patients, DLBCL patients, mucinous adenocarcinoma patients and non mucinous adenocarcinoma patients are 4,7,5 and 27. And the number of involvement of gastric body patients of them are:14,16,13 and 28. And the number of involvement of gastric fundus patients of them are 5,7,2 and 16. And the number of gastric sinus involvement patients of them are: 3,17,9 and 27. The difference of gastric sinus involvement between them was statistically significant(χ2=14.101,P<0.05). The difference of cardiac involvement, involvement of gastric body and involvement of gastric fundus between them was not statistically significant(P>0.05). The number with stiff gastric wall of MALT patients, DLBCL patients, mucinous adenocarcinoma patients and non mucinousadenocarcinoma patients are 1, 10, 8, 26. The number with ulcer mucosa are 6, 18, 10, 34. The difference of gastric wall form and mucosal ulcer was statistically significant(χ2=11.221,P<0.05;χ2=10.028,P<0.05).Conclusions:PET-CT is favorable to the diagnosis and differentiation between PGL and gastric carcinoma.Compare with PGL patients, gastric carcinoma patients are more likely show up with stiff gastric or ulcer mucosa especial non mucinous adenocarcinoma patients. As the part of systemic lymphoma, PGL is more easily to cause splenomegaly. The FDG uptake values were different for MALT patients, DLBCL patients, non mucinous adenocarcinoma patients and mucinous adenocarcinoma patients. The SUVmax values of DLBCL patients were higher. The SUVmax values of MALT patients and mucinous adenocarcinoma patients are significantly lower than the other two kinds of patients. And the FDG uptake values of the other two kinds of patients were lower, PET-CT may show false negative results, so we must be on the alert of them. Gastric carcinoma and PGL can showed up with Ⅰ,Ⅱ,Ⅲ type. AndⅠ,Ⅲ type are commonly with MALT or DLBCL, and Ⅱ,Ⅲ type are commonly with mucinous adenocarcinoma or non mucinous adenocarcinoma. 58(45.7%) patients’ tumor accumulated to a plurality of position of gastric tissue, with statistical analysis we found that the tumor of DLBCL and gastric carcinoma are more easily cause gastric sinus involvement. |
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