Autoradiographic evaluation of 99mTc-methylene diphosphonate accumulation in oral cancer invading the mandible

Abstract Purpose: Skeletal scintigraphy, a sensitive diagnostic tool used to detect changes in bone, is helpful for evaluating bone invasion by oral cancer. However, the exact sites of accumulation of 99m Tc-phosphate compounds in the mandible have not yet been fully elucidated. The aim of this study was to determine the localization of 99m Tc-methylene diphosphonate (MDP) in the areas of mandible that have been invaded by cancer. Patients and Methods: Seven patients with oral cancer (lower gingiva, 4; tongue, 2; floor of the mouth, 1) who underwent surgical treatment with mandibular bone resection were included in the study. Autoradiography and contact macroradiography were used for evaluation of 99m Tc-MDP accumulation. Results: Radioactivity reflecting accumulation of 99m Tc-MDP was documented encircling the portion of the mandible with cancerous invasion, suggesting that 99m Tc-MDP accumulated in immature bone. High uptake also was found in the periosteal reactive bone around the cortical bone. Conclusions: The amount of increased 99m Tc-MDP circumscribing carcinoma invasion varies among cases. Additionally, uptake may not correspond directly with the amount of the carcinoma invasion; that seen in periosteal bone could be attributed mistakenly to bone invasion in planar scintigraphy.