percutaneous microwave ablation of thyroid nodules: efficacy evaluation with 99m tc - pertechnetate and 99mtc-mibi functional imaging

Background: local ablative treatments play an important role for patients who cannot be treated surgically. radiofrequency ablation is a wellestablished alternative to surgical treatment of thyroid nodules, however it also has disadvantages. microwave ablation (mwa) is a new minimally invasive treatment promising several improvements. the aim of this retrospective study was to evaluate the effects of microwave ablation on thyroid nodules by 99mtcpertechnetate and 99mtcmibi scintigraphy. materials and methods: 30 patients with overall 40 nodules were treated. for the ablation of thyroid nodules, a microwave generator working with frequencies from 902 to 928 mhz was used. the ablation time ranged between 120 and 300 seconds per ablation zone. the target temperatures ranged between 6080 deg;c. pre and post interventional, the radionuclide uptake was determined using a thyroid specific scintillation camera. for 27 cold nodules 99mtcmibi was used for evaluation; 13 indifferent nodules were measured with 99mtcpertechnetate. results: the relative change of uptake was detected as a quotient of pre and post therapeutic uptake. the statistical analysis of scintigraphy data proved the efficacy of microwave ablation. 99mtcpertechnetate scintigraphy showed an uptake reduction of 39% (range 9 to 85%). 99mtcmibi imaging showed a median reduction of 40% (plt;0.01) (range 7 to 100%). conclusion: the determined results show the effectiveness of mwa as a treatment option for benign thyroid nodules. with functional scintigraphy a significant activity decrease could be detected in the ablation zone; hence a verification of affectivity was possible after a short period of time.