18F-fluorodeoxyglucose Positron Emission Tomography/computed Tomography Comparison of Gastric Lymphoma and Gastric Carcinoma

Abstract ObjectiveThis study aimed to compare the characteristics of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in gastric lymphoma (GL) and gastric carcinoma (GC).METHODSPatients with newly diagnosed GL or GC who underwent 18F-FDG PET/CT prior to treatment were included in this study. The PET/CT features of gastric wall lesions, including FDG avidity, pattern, and intensity [maximal standard uptake value (SUVmax)] were reviewed and analyzed. The correlation of SUVmax with gastric clinicopathological variables was investigated by Student’s t test, Mann-Whitney U test, chi-square test, and receiver-operating characteristic (ROC) curve analysis to determine the differential diagnostic value of SUVmax-associated parameters in GL and GC.RESULTSA total of 68 patients with GL and 117 with GC were included in this study. Abnormal gastric FDG accumulation was found in 66 (97.05%) patients with GL and 109 (93.16%) patients with GC. Majority of the GL patients presented with type I and III lesions, whereas GC patients mainly with type II and III lesions. The SUVmax [14.89(6.56，22.12) vs 4.08(5.75，10.24), P<0.001) and SUVmax/THKmax (maximal thickness) [0.72(0.50,1,10) vs 0.39(0.28,0.64), P<0.000] were both higher in patients with GL when compared with GC. The SUVmax was higher in GL patients with DLBCL than in those with MALT (17.51±10.31 vs 4.97±2.92, P =0.0010) and higher in patients with advanced Lugano stage (II1/II2/IV) than in those with stage I (18.27±10.19 vs 9.92±9.22, P = 0.002). In GC patients, the SUVmax was higher in T3+T4 than in T1+T2 [6.79(4.47,12.41) vs 4.09(2.32,6.31), P = 0.000], but there were no significant differences between TNM stage I+II and TNM stage III+IV. The ROC curve analysis suggested a better performance of SUVmax/THKmax in evaluating gastric lesions between GL and GC when compared to SUVmax alone. The sensitivity of SUVmax and SUVmax/THKmax for differential diagnosis of GL and GC were 0.917 and 0.578, respectively. However, the specificity of SUVmax/THKmax for differential diagnosis of GL and GC was higher than that of SUVmax alone (0.894 VS 0.485).CONCLUSIONThe PET/CT features differed between GL and GC, and these can improve the evaluation of PET/CT of gastric wall lesions and help differentiate GL from GC.