In 2016, there were 203,000 new cases of thyroid cancer in China, ranking 7th among all malignant tumours and 4th among women, and showing a rapid growth trend. Papillary thyroid cancer (PTMC) with a diameter of ≤10 mm is the most common type of thyroid cancer, accounting for about 50% to 60% of the total number of cases. Low-risk PTMC is the most common type of thyroid cancer, with low invasiveness and good prognosis. Surgery is the treatment of choice for low-risk PTMC, but it significantly affects the quality of life of patients by affecting the function of the thyroid gland and requiring long-term medication after surgery, as well as having a high incidence of intra- and postoperative complications; there are certain impacts and limitations in the actual treatment. Microwave ablation (MWA) is a therapeutic modality emerging in recent years, which has the characteristics of easy operation, precise positioning, safety and effectiveness, small postoperative damage, fast recovery, fewer complications, and does not affect the aesthetics of the patient, which not only avoids surgical trauma and reduces the anxiety of the patient, but also better preserves the function of the thyroid gland, and its clinical application is becoming more and more widespread. In recent years, the application of microwave ablation in the treatment of PTMC has received more and more attention. Ultrasound, as a first-line examination tool, is accepted by the majority of patients because of its advantages of safety, speed, efficiency, low price and painlessness. Contrast-enhanced ultrasound (CEUS) is a new examination technique developed in recent years, which can provide richer and clearer diagnostic information than conventional ultrasound and colour Doppler ultrasound. Ultrasound contrast agents (e.g. Sonovue, Sonazoid), Sonovue with sulphur hexafluoride microbubbles as the main ingredient and Sonazoid with perfluorobutane microbubbles as the main ingredient, are non-toxic, non-radioactive, do not require allergy testing, and do not have the advantages of liver or kidney toxicity, etc., and are increasingly recognised by the public. Ultrasonography is now widely used in clinical practice as the primary modality for assessing efficacy after thyroid ablation therapy. Molecular diagnosis is one of the most important tools for preoperative diagnosis and invasiveness assessment of thyroid cancer. Common thyroid cancer gene variants include point mutations such as BRAF V600E, RAS, TP53, PIK3CA, and gene integration variants such as CCDC6-RET and ETV6-NTRK3. This project intends to assess the efficacy and prognosis of microwave ablation therapy for micropapillary thyroid cancer by ultrasonography combined with genetic molecular diagnosis, which in turn will assist in clinical treatment decisions.