分析甲状腺髓样癌高频超声图像特征，并比较最大径＞1.0 cm及≤1.0 cm的超声图像特征的差异。

回顾性分析2016年1月至2019年12月在解放军总医院第一医学中心接受超声检查及手术切除的36例甲状腺髓样癌患者的临床资料、超声图像及病理结果。总结甲状腺髓样癌病灶的超声特征，并依病灶最大径分为＞1.0 cm及≤1.0 cm两组，比较两组间超声图像表现的差异。

甲状腺髓样癌病灶共42个，最大径为（2.6±1.5）cm（0.4~5.4 cm）。甲状腺髓样癌主要分布于甲状腺中上极（32个，76.2%），所有病灶均为低回声，以实性为主（39个，92.8%），多数伴有钙化（25个，59.5%）。与≤1.0 cm的病灶相比，＞1.0 cm的甲状腺髓样癌病灶血流信号多丰富（65.5% vs 7.7%，P=0.001），颈部淋巴结转移比例更高（79.3% vs 15.4%，P＜0.001），病灶超声诊断准确性更高（93.1% vs 61.5%，P=0.037）。

甲状腺髓样癌病灶主要分布于甲状腺中上极，实性低回声为主，多数伴有钙化。不同大小甲状腺髓样癌超声特征不同，准确理解这些特征有助于甲状腺髓样癌的早期诊断和治疗。

To analyze the high-frequency ultrasound (US) features of medullary thyroid carcinoma (MTC), and to compare the differences between MTC with the maximum diameter of ＞1.0 cm and ≤1.0 cm.

The clinical data, US images, and pathological results of 36 MTC patients who underwent high-frequency US examination and surgical resection at the First Medical Center of Chinese PLA General Hospital from January 2016 to December 2019 were analyzed retrospectively. The US features of MTC were summarized and a comparative study was performed between subgroups with the maximum diameter of ＞1.0 cm and ≤1.0 cm.

Forty-two MTC lesions with the maximum mean diameter of (2.6±1.5) cm (range, 0.4-5.4 cm) were enrolled in this study. MTC lesions were mainly distributed in the middle and upper poles of the thyroid (32, 76.2%); all were hypoechoic, 39 of them were mainly solid (39, 92.8%), and most of them had calcifications (25, 59.5%). Compared with lesions with the maximum diameter of ≤1.0 cm, the blood flow signal of lesions with the maximum diameter of ＞1.0 cm was more abundant (65.5% vs 7.7%, P=0.001); the rate of cervical lymph node metastasis in patients with lesions ＞1.0 cm was higher (79.3% vs 15.4%, P＜0.001), and US diagnosis accuracy in these cases was higher (93.1% vs 61.5%, P=0.0.037).

Most MTCs are located in the middle and upper poles of the thyroid, with solid component, hypo-echogenicity, and calcifications. Different sizes of MTC have different US features. Accurate differentiation of these US features is helpful for the early diagnosis and treatment of MTC.