Clinical Research Of Ultrasound-guided Percutaneous Radiofrequency Ablation For Benign Thyroid Nodules

Objective: To investigate the clinical effectiveness of ultrasound-guidedpercutaneous ablation for benign thyroid nodules.Methods:1. A total of72benign thyroid nodules in45patients were dignosed as benign byfine needle aspiration biopsy(FNAB). Before ablation, the US examination,lastosonographic characteristics, and laboratory studies were performed with all patients.The volume, composition, intra-nodular vascularity, elastosonographic characteristics,locations were evaluated to make sure the puncture route was optimal.2．The patients were placed in the supine position with the neck extended.2%lidocaine was injected for the local anesthesia of the puncture route. The mixture oflidocaine and saline was injected around thyroid to protect vital organs from beinginjured. An catheter needle was inserted into the thyroid nodule under US guidance,took out the needle core and inserted the electrode tip, turned on ablation system. Whenthe ablation system working, the area of the nodule became transit hyperechoic zone.While the buzzer warned, it meaned that ablation was over. We determined the numberof ablation according to the size of nodule. The turn of ablation was from deep toshallow, from remote to near. We did not stop ablation untill the nodule was covered byhyperechoic area, no color flow signal.3. After RF ablation, US examinations were preformed at1,3,6and12months,untill the ablation zone was absorbed completely. We measured the size andcalculated the volume reduction ratio (%, VRR) in the same way as before RFablation. Intra-nodular vascularity and elastosonographic characteristics were alsoevaluated. The thyroid function test (TFT) was carried out one week after ablation. Thecomplications were assessed during the follow-up.Results：1. Ultrasonographic features: When ablation ended, the ablation zone showed ill-defined yperechoic area. At the follow-up, the ablation zone showed well-definedhypoecho area, no color flow signal.2. The volume and VRR of the ablation zone: At6months follow-up, the volumesof ablation zone were smaller significantly than the initial nodules(p<0.001). VRRgreater than50%was observed in44.94%,78.69%,56.1%,100%at every follow-up.4.92%,9.02%,25.0%index nodules had disappeared at3,6months and the lastfollow-up. At1month follow-up, the mix nodules decreased in size more than theothers, but there was no significant between the types of nodules at the other follow-up.3. Ultrsound-elastography evaluation: As the elapse of time, the ablation zonessoftened gradually, the grade of the ultrsound-elastosonography (US-E) reduced. At1,3,6months and last follow-up, the grade of US-E was Ⅲ, Ⅳ for80.73%,36.67%,18.52%,0.00%separately, and the grade of US-E was Ⅰ, Ⅱfor19.28%,63.33%,81.48%,100%separately. The elastographic grades of the mixed nodules and the solidnodules were of significant difference statistically (p<0.001), but there was nosignificant between the types of nodules at the other follow-up.4. Thyroid function:93.22%of the patients were in normal range. The TSH haddecreased, the FT3、FT4had increased in3patients. The TSH had decreased, the A-TGhad increased in1patients, with no clinical symptom, they had normalized at the1month follow-up without treatment.5. Complications: There was no serious complications. During the ablation,hematoma developed in2patients, stopped ablation immediately and observed30minute to make sure there was no active bleeding, the ablation went on. All patientscomplained slight pains, which were eased the next day. When the capsule of dorsalthyroid was separated, patients complained voice changed and throat discomfort slightly,which would be eased within hours to days.Conclusion:1. Ultrasound-guided percutaneous radiofrequency ablation is effective, beautifuland controllable，and minimally invasive treatment for benign thyroid nodules.2. At6months follow-up, ablation zones absorpt rapidly, later the speed ofabsorption decreased.6months after ablation was the key time point for evaluating theeffectiveness of ablation.3．As the elapse of time, the ablation zones softened gradually，the grade of theelastography reduced. The ultrsound-elastosonography can evaluate the absorption ofablation zones.