Abnormal Focal Jaw Uptake of 153 Sm-Ethylene-Diamine-Tetra- Methylene-Phosphonate (EDTMP) - What is the Reason?

Abnormal focal tracer uptake in the jaw during conventional bone scintigraphy is a quite frequent finding usually not related to malignant disease. In patients undergoing radionuclide therapy with lanthanoids or rhenium, the appearance is also quite frequent. ItAS¼s origin so far has not been studied in a large number of patients. Objective, to evaluate the underlying reason of abnormal focal tracer uptake in the jaw in patients who underwent 153Sm-EDTMP therapy for painful metastatic lesions. Methods, out of 138 patients, 82 revealed a positive result, 60 males and 22 females (mean age: 63.9 ± 13.9years; range 19-90 years), with metastatic bone pain were examined. Their lesions were judged by a dentist clinically and radiologically. Results, the most frequent reason of increased focal uptake in the group of mainly prostate and breast cancer patients was inflammation in 13 (24.5%) and 9 (41%) patients, respectively. In the patients below 70 years of age, inflammation was the most frequent reason with (32.7%) while in the older ones of 70 years, it was mechanically irritated by a prosthesis with (50%). In 4 of the patients, the increased uptake of 153Sm-EDTMP was due to metastatic disease as shown by PET/CT and/or MRI. Conclusion, although the number of secondary lesions in the jaw is small (4.8%), the underlying reason in conventional bone scintigraphy as well as in post-therapeutic scintigraphy should be always evaluated.