Effects of Intratumoral Inflammatory Process on 18F-FDG Uptake: Pathologic and Comparative Study with 18F-Fluoro-?±-Methyltyrosine PET/CT in Oral Squamous Cell Carcinoma

摘要

id="p-2">The accurate depiction of both biologic and anatomic profiles of tumors has long been a challenge in PET imaging. An inflammation, which is innate in the carcinogenesis of oral squamous cell carcinoma (OSCC), frequently complicates the image analysis because of the limitations of 18F-FDG and maximum standardized uptake values (SUV_max). New PET parameters, metabolic tumor volume (MTV) and total lesion glycolysis (TLG), as well as 18F-fluoro-?±-methyltyrosine (18F-FAMT), a malignancy-specific amino acid-based PET radiotracer, are considered more comprehensive in tumor image analysis. Here, we showed the substantial effects of the intratumoral inflammatory process on 18F-FDG uptake and further study the possibility of MTV and TLG to predict both tumor biology (proliferation activity) and anatomy (pathologic tumor volume). >Methods: 18F-FDG and 18F-FAMT PET images from 25 OSCC patients were analyzed. SUV_max on the tumor site was obtained. PET volume computerized-assisted reporting was used to generate a volume of interest to obtain MTV and TLG for 18F-FDG and total lesion retention (TLR) for 18F-FAMT. The whole tumor dissected from surgery was measured and sectioned for pathologic analysis of tumor inflammation grade and Ki-67 labeling index. >Results: The high SUV_max of 18F-FDG was related to the high inflammation grade. The SUV_max ratio of 18F-FDG to 18F-FAMT was higher in inflammatory tumors (P 0.05) whereas the corresponding value in tumors with a low inflammation grade was kept low. All 18F-FAMT parameters were correlated with Ki-67 labeling index (P 0.01). Pathologic tumor volume predicted from MTV of 18F-FAMT was more accurate (R = 0.90, bias = 3.4 ?± 6.42 cm3, 95% confidence interval = 0.77-6.09 cm3) than that of 18F-FDG (R = 0.77, bias = 8.1 ?± 11.17 cm3, 95% confidence interval = 3.45-12.67 cm3). >Conclusion: 18F-FDG uptake was overestimated by additional uptake related to the intratumoral inflammatory process, whereas 18F-FAMT simply accumulated in tumors according to tumor activity as evaluated by Ki-67 labeling index in OSCC.