en Radiation Biology Radiation Biology تحقيق بديع Original Research <p style="text-align: justify;"><strong>Background: </strong>Local ablative treatments play an important role for patients who cannot be treated surgically. Radiofrequency ablation is a well-established 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 ^99mTc-pertechnetate and ^99mTc-MIBI scintigraphy. <strong>Materials and Methods:</strong> 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&nbsp; 300 seconds per ablation zone. The target temperatures ranged between 60-80 &deg;C. Pre- and post- interventional, the radionuclide uptake was determined using a thyroid specific scintillation camera. For 27 cold nodules ^99mTc-MIBI was used for evaluation; 13 indifferent nodules were measured with ^99mTc-pertechnetate. <strong>Results:</strong> 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. ^99mTc-pertechnetate scintigraphy&nbsp; showed an uptake reduction of 39% (range 9 to 85%). ^99mTc-MIBI imaging showed a median reduction of 40% (p<0.01) (range 7 to 100%). <strong>Conclusion:</strong> 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.</p> <p></p> Thyroid nodules, microwave ablation, 99mTc-pertechnetate scintigraphy, 99mTc-MIBI scintigraphy, functional imaging 91 98 http://ijrr.com/browse.php?a_code=A-10-1-603&slc_lang=en&sid=1 K. Heck kristina.heck@web.de 790031947532846008031 790031947532846008031 Yes Frankfurt University Hospital Y. Korkusuz 790031947532846008032 790031947532846008032 No Frankfurt University Hospital C. Happel 790031947532846008033 790031947532846008033 No Frankfurt University Hospital F. Grünwald 790031947532846008034 790031947532846008034 No Frankfurt University Hospital H. Korkusuz 790031947532846008035 790031947532846008035 No Frankfurt University Hospital