Percutaneous microwave ablation of benign thyroid nodules. Functional imaging in comparison to nodular volume reduction at a 3-month follow-up.

AIM

Thyroid nodules represent a common clinical issue. Amongst other minimally invasive procedures, percutaneous microwave ablation (MWA) poses a promising new approach. The goal of this retrospective study is to find out if there is a correlation between volume reduction after 3 months and 99mTc-uptake reduction of treated thyroid nodules.

PATIENTS, METHODS: 14 patients with 18 nodules were treated with MWA. Pre-ablative assessment included sonographical and functional imaging of the thyroid with 99mTc-pertechnetate and 99mTc-MIBI. Additionally, patients underwent thyroid scintigraphy 24 hours after ablation in order to evaluate the impact of the treatment on a functional level and to ensure sufficient ablation of the targeted area. At a 3-month follow-up, ultrasound examination was performed to assess nodular volume reduction.

RESULTS

Mean relative nodular volume reduction after three months was 55.4 ± 17.9% (p < 0.05). 99mTc-uptake 24 hours after treatment was 45.2 ± 31.9% (99mTc-MIBI) and 35.7 ± 20.3% (99mTc-pertechnetate) lower than prior to ablation (p < 0.05). Correlating reduction of volume and 99mTc-uptake, Pearson's r was 0.41 (p < 0.05) for nodules imaged with 99mTc-MIBI and -0.98 (p < 0.05) for 99mTc-pertechnetate. According to scintigraphy 99.6 ± 22.6% of the determined target area could be successfully ablated.

CONCLUSIONS

MWA can be considered as an efficient, low-risk and convenient new approach to the treatment of benign thyroid nodules. Furthermore, scintigraphy seems to serve as a potential prognostic tool for the later morphological outcome, allowing rapid evaluation of the targeted area in post-ablative examination.