Analysis of ¹⁸F-FDG maximum standardized uptake value in gastric cancer with coincidence imaging

Objective: To investigate the value of ¹⁸F-FDG SUV_max in gastric cancer diagnosis with coincidence imaging. Methods: The coincidence imaging was performed in 92 patients with gastric diseases (60 males, 32 females,age 65 (32-85) years; 78 malignant cases, 14 benign cases). The malignant cases included 3 remnant gastric cancers and 75 primary gastric cancers (staging: 4 of T_is, 13 of T₁, 9 of T₂, 33 of T₃, 11 of T₄ and 5 without surgery). The well-, moderately-and poorly-differentiated adenocarcinomas were 22, 15 and 28, respectively. Images were analyzed retrospectively with visual method and ¹⁸F-FDG SUV_max, and the diagnostic results were compared with the histopathological findings. The ROC curve was used to analyze the SUV_max. The Pearson's correlation analysis was performed to evaluate the relationship between SUV_max and tumor size. The Wilcoxon rank sum test was applied to determine the difference of SUV_max between early and advanced gastric cancers. The Kruskal-Wallis test was used to analyze the difference of SUV_max in various types of differentiated adenocarcinoma. Results: No matter visual method or SUV_max was used, the sensitivity, specificity and accuracy of coincidence imaging in diagnosis of gastric cancer were 64.1% (50/78), 64.3% (9/14) and 64.1% (59/92), respectively. The AUC of SUV_max was 0.695 and the cut-off value was 0.700. SUV_max Was positively correlated with tumor size significantly (r=0.489, P<0.001). There was statistically significant difference between SUV_max of T_is-1 and that of T_2-4 (0.676± 1.288 vs 3.851 ±3.764; Z=-3.754, P<0.001). However, there was no statistically significant difference among SUV_max of various grades of differentiated adenocarcinoma(2.805±4.008, 3.447±2.365, 3.413± 3.737; χ²=2.459, P> 0.05). Conclusions: SUV_max provides more information than visual method in assessing gastric cancer with ¹⁸F-FDG coincidence imaging. Appropriate cut-off value of SUV is necessary for improvement of the diagnostic efficiency. Relationships between SUV and pathological T stage, histopathological types and differentiation degree need further investigation. (authors)