Ultrasonography Diagnosis and Imaging-Based Management of Thyroid Nodules: Revised Korean Society of Thyroid Radiology Consensus Statement and Recommendations

Abstract

The rate of detection of thyroid nodules and carcinomas has increased with the widespread use of ultrasonography (US), which is the mainstay for the detection and risk stratification of thyroid nodules as well as for providing guidance for their biopsy and nonsurgical treatment. The Korean Society of Thyroid Radiology (KSThR) published their first recommendations for the US-based diagnosis and management of thyroid nodules in 2011. These recommendations have been used as the standard guidelines for the past several years in Korea. Lately, the application of US has been further emphasized for the personalized management of patients with thyroid nodules. The Task Force on Thyroid Nodules of the KSThR has revised the recommendations for the ultrasound diagnosis and imaging-based management of thyroid nodules. The review and recommendations in this report have been based on a comprehensive analysis of the current literature and the consensus of experts.

Keywords: Ablation techniques; Lymph nodes; Multidetector computed tomography; Thyroid neoplasm; Thyroid nodule; Ultrasonography.

Fig. 1. Algorithm of K-TIRADS for malignancy risk stratification based on solidity and echogenicity of thyroid nodules.

Modified from Na et al. Thyroid 2016;26:562-572 (25). ^*Microcalcification, nonparallel orientation, spiculated/microlobulated margin. K-TIRADS = Korean Thyroid Imaging Reporting and Data System, US = ultrasonography

Fig. 2. Korean Thyroid Imaging Reporting and Data System 5 (high suspicion).

A. Solid hypoechoic nodule with microcalcifications. B. Solid hypoechoic nodule with multiple microcalcifications and macrocalcifications. C. Solid hypoechoic nodule with non-parallel orientation. D. Solid hypoechoic nodule with spiculated/microlobulated margin. Diagnosis: papillary carcinoma (A-D).

Fig. 3. Korean Thyroid Imaging Reporting and Data System 4 (intermediate suspicion).

A. Solid hypoechoic nodule without suspicious US features. Diagnosis: benign follicular nodule. B. Solid isoechoic (predominantly isoechoic) nodule with microcalcification. Diagnosis: benign follicular nodule. C. Predominantly solid hypoechoic nodule with multiple microcalcifications. Diagnosis: papillary carcinoma. D. Predominantly cystic hypoechoic nodule with microcalcification (arrow). Diagnosis: papillary carcinoma. US = ultrasonography

Fig. 4. Korean Thyroid Imaging Reporting and Data System 3 (low suspicion).

None of nodules have any suspicious US features such as microcalcification, non-parallel orientation, and spiculated/microlobulated margins. A. Solid isoechoic nodule. Diagnosis: follicular variant papillary carcinoma. B. Predominantly solid and isoechoic nodule. Diagnosis: benign follicular nodule. C. Predominantly solid and hypoechoic nodule. Diagnosis: benign follicular nodule. D. Predominantly cystic and isoechoic nodule. Diagnosis: benign follicular nodule. US = ultrasonography

Fig. 5. Korean Thyroid Imaging Reporting and Data System 2 (benign).

A. Spongiform nodule. Diagnosis: benign (FNA not performed). B. Spongiform nodule with tiny microcystic changes. Diagnosis: benign follicular nodule. C. Predominantly cystic nodule with multiple comet tail artifacts. Diagnosis: benign follicular nodule with colloid. D. Cyst with comet-tail artifact. Diagnosis: benign (colloid cyst, FNA not performed). FNA = fine-needle aspiration

Fig. 6. Suspicious lymph nodes (ultrasonography features).

A. Large cystic nodal mass. B. Small focal cystic change and hyperechogenicity in lymph node. C. Hyperechogenicity and macrocalcifications in lymph node. D. Multifocal hyperechogenicity (black arrows) and microcalcification (white arrow) in lymph node. E. Hyperechogenicity, microcalcification, and abnormal hypervascularity in lymph node. Diagnosis: metastatic papillary carcinoma (A-E).

Fig. 7. Suspicious lymph nodes (CT features).

A. Large nonenhancing cystic nodal mass. B. Small focal cystic change and strong enhancement in lymph node. C. Diffuse, strong enhancement in lymph node. D. Heterogeneous mild enhancement in lymph node (arrow). E, F. Multiple variable-sized nodal calcifications and tiny nodal calcification (F, arrow) on unenhanced CT image. Diagnosis: metastatic papillary carcinoma (A-F).

Fig. 8. Indeterminate lymph nodes.

A, B. US features of indeterminate lymph nodes. US images shows ovoid and elongated lymph nodes which show loss of central echogenic hilum and central hilar vascularity. Note absence of any suspicious US feature in these nodes. Diagnosis: probable benign lymph node (FNA not performed). C, D. CT features of indeterminate lymph nodes. CT images show lymph nodes that do not have central fat hilum and central hilar vessel enhancement. Note absence of any suspicious CT feature in these nodes. Diagnosis: probably benign lymph node (arrow) (C, FNA not performed), metastatic papillary carcinoma (arrow) (D). FNA = fine-needle aspiration, US = ultrasonography

Fig. 9. Benign lymph nodes.

A, B. US features of benign lymph nodes. US image shows elongated lymph node with prominent central echogenic hilum and central hilar vascularity (A). US image shows ovoid lymph node with small deformed echogenic hilum (arrow), however, color-Doppler US shows prominent typical central hilar vascularity (B). C, D. CT features of benign lymph nodes. CT image shows lymph node with central hilar fat (C, arrows) and enhanced lymph node with central hilar vessel enhancement (D, arrow). Diagnosis: benign lymph node (A-D, FNA not performed). FNA = fine-needle aspiration, US = ultrasonography