mmon clinical scenario [1]. The prevalenceof thyroid nodules is ~18-40% in Chineseadults [2]; however, only 5-10 percent of allthyroid nodules are malignant. Although withthe development of the ultrasound technique,several ultrasonographic characteristics havebeen associated with thyroid malignancy[3], individual ultrasound features arenot accurate predictors of thyroid cancer.Thyroid fine-needle aspiration [FNA] hasbeen recommended by various organizationsfor the more precise preoperative diagnosisof thyroid nodules [4]. Non-diagnostic rateof FNA comparison and estimate betweenthe other studiesMaterials and Мethods: We performedover 100 FNA using one pass of the 21-Gneedle attached to a 10 ml syringe withoutlocal anesthesia in 2015. All the FNAswere performed without the guidance ofultrasound. Recent study 100 cases of themwere not selected for a specific method.Results: In total there were 100 patientsrecruited in the study with a mean ageof 45.94±13.13 years and 83.0% femalepatients.The Non-diagnostic rate was comparedbetween groups with different needlesizes and methods. In the 22 G group,non-aspiration showed a decreased NDrate as compared to aspiration [44.21 vs.76.76%, P<0.001;]. In the non-aspirationgroup, a lower ND rate was revealed in the25-G needle group compared to the 22-Gneedle group [34.97 vs. 44.21%, P=0.032;].Notably, the ND rate in the 25 G group wassignificantly lower than in the all 22 G group[34.97 vs. 58.13%, P<0.001;]. In the 21 Ggroups, aspiration showed a decreased NDrate as compared to aspiration [44.21 vs.76.76%, P<0.001;]. 21G aspiration groupshowed decrease twofold ND rate ascompared 22G aspiration group [31.63 vs.76.76%, P<0.001;]Conclusion: There have been studiesusing various needle types [regular needle,needle with a stylet or spinal needle [5]and different needle sizes from [21 G to27 G] with or without aspiration duringthe procedure. Numerous factors influencethe diagnostic rate in thyroid FNA, amongwhich the nodule component is an extremelyimportant factor [6]. In general, the morecystic the percentage of each nodule, thehigher the rate of non-diagnostic, with the lowest ND rate in the solid nodule using a25-G needle at 26.77% and the highest inthe cystic nodule using 22 G aspiration at85.19%. A similar trend was found in eachgroup with lowest rate of ND in the 25 Gnon-aspiration group and highest in the 22G aspiration group.

Background: Thyroid nodules (TNs) are a common clinical issue, and their prevalence has been increasing over the last 2 decades [1] due to the widespread use of ultrasound (US) imaging. More than 50% of TNs are detected with US examination In the general population, while only 3–7% are detected with palpation [2]. Nodular goiter is the most common cause of thyroid disease in Mongolia, as in other countries. Recent guidelines suggest that a nodule without clinical symptoms should be treated with watchful waiting; however, some patients require treatment because of cosmetic problems or symptoms. There are several treatment options, but neither is perfect. The main treatment of the disease is still the traditional surgical resection. it still carries a 2–10% prevalence of complications, such as neck scarring, hypothyroidism, transient or definitive postoperative hypoparathyroidism, recurrent laryngeal nerve injury, and the recognized risks associated with general anesthesia [3,4]. Minimally invasive alternatives have been explored. Laser ablation, microwave ablation, HIFU, and radiofrequency ablation (RFA) are safe and effective techniques for the treatment of nodular goiter. it is possible to treat small nodules early and enlarge them before surgical intervention is indicated. We have introduced a new method of RFA treatment (2019) in our country. Purpose: To assess the effectiveness of radiofrequency ablation (RFA) for cystic thyroid nodules. Material and Method: This retrospective study was approved by the Research Ethics Committee of the Mongolian National University of Medical Sciences and informed consent was obtained from all patients before RFA. The study was conducted from 9th Jan 2019 to 15th Oct 2021, 485 nodules from 183 patients (M:F=9:174; mean age±SD=46.3±11.4 years) who met the eligibility criteria and provided written informed consent were enrolled at the First Central Hospital of Mongolia. Nodules were assessed pre-treatment and at 1, 3, 6, 12, and 24 months post-treatment. Nodule volume were recorded at each time point.
The primary endpoint was the volume reduction ratio (percentage) at 1, 3, 6, 12, and 24 months follow-up. Results: For the primary outcome of nodule volume reduction, the absolute volume reduction at the 24-month follow-up was 45 (77.6%). Completely destroyed 10 (17.2%), volume increased by 3 (5.2%) (table. 3). The median volume reductions at the 1, 3, 6, 12, and 24-months follow-ups were 34.9%, 61.0%, 74.9%, 83.3% and 74.0% respectively. Median volume statistically decreased by a significant p=0.0001. At 3 months follow up after RFA, the nodules decreased most. All study subjects recovered without sequelae. Therefore, no patient experienced a life-threatening or delayed complication during the follow-up. Conclusion Our study demonstrates that RFA is a safe and effective treatment for cystic thyroid nodules. Advantages of RFA include no surgical scars or general anesthesia, low complication rates, and avoiding lifelong thyroid hormone replacement.