Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Active surveillance (AS) has been widely adopted as an alternative to immediate surgery owing to the indolent nature and favorable outcomes of papillary thyroid microcarcinoma (PTMC). AS is generally recommended for tumors measuring ≤1 cm without aggressive cytological subtypes, risk of gross extrathyroidal extension (ETE), lymph node metastasis (LNM), or distant metastasis. AS requires careful patient selection based on various patient and tumor characteristics, and ultrasound (US) findings. Moreover, during AS, regular US is performed to monitor any signs of tumor progression, including tumor growth, new US features of potential gross ETE, and LNM. Therefore, appropriate imaging-based assessment plays a crucial role in determining whether AS or surgery should be pursued. However, detailed recommendations concerning US evaluation are currently insufficient, necessitating the formulation of this guideline. The Korean Society of Thyroid Radiology has developed a consensus statement for low-risk PTMC, covering US assessment methods when considering AS as a management option and conducting follow-up imaging tests during AS. This guideline aims to provide optimal scientific evidence and expert opinion consensus regarding a standardized US-based assessment protocol for low-risk PTMC.

Active surveillance (AS) has been widely adopted as an alternative to immediate surgery owing to the indolent nature and favorable outcomes of papillary thyroid microcarcinoma (PTMC). AS is generally recommended for tumors measuring ≤1 cm without aggressive cytological subtypes, risk of gross extrathyroidal extension (ETE), lymph node metastasis (LNM), or distant metastasis. AS requires careful patient selection based on various patient and tumor characteristics, and ultrasound (US) findings. Moreover, during AS, regular US is performed to monitor any signs of tumor progression, including tumor growth, new US features of potential gross ETE, and LNM. Therefore, appropriate imaging-based assessment plays a crucial role in determining whether AS or surgery should be pursued. However, detailed recommendations concerning US evaluation are currently insufficient, necessitating the formulation of this guideline. The Korean Society of Thyroid Radiology has developed a consensus statement for low-risk PTMC, covering US assessment methods when considering AS as a management option and conducting follow-up imaging tests during AS. This guideline aims to provide optimal scientific evidence and expert opinion consensus regarding a standardized US-based assessment protocol for low-risk PTMC.

Background: We aimed to evaluate the utility of repeat biopsy of thyroid nodules classified as atypia of undetermined significance with architectural atypia (IIIB) on core-needle biopsy (CNB). Methods: This retrospective study evaluated patients with thyroid nodules categorized as IIIB on CNB between 2013 and 2015. Demographic characteristics, subsequent biopsy results, and ultrasound (US) images were evaluated. The malignancy rates of nodules according to number of CNBs and the number of IIIB diagnoses was compared. Demographic and US features were evaluated to determine factors predictive of malignancy. Results: Of 1,003 IIIB nodules on CNB, the final diagnosis was determined for 328 (32.7%) nodules, with 121 of them confirmed as malignant, resulting in a malignancy rate of 36.9% (95% confidence interval, 31.7% to 42.1%). Repeat CNB was performed in 248 nodules (24.7%), with 75 (30.2%), 131 (52.8%), 13 (5.2%), 26 (10.5%), one (0.4%), and two (0.8%) reclassified into categories II, IIIB, IIIA, IV, V, and VI, respectively. Malignancy rates were not significantly affected by the number of CNBs (P=0.291) or the number of IIIB diagnoses (P=0.473). None of the nodules confirmed as category II on repeat CNB was malignant. US features significantly associated with malignancy (P<0.003) included solid composition, irregular margins, microcalcifications, and high suspicion on the US risk stratification system. Conclusion Repeat biopsy of nodules diagnosed with IIIB on CNB did not increase the detection of malignancy but can potentially reduce unnecessary surgery. Repeat biopsy should be performed selectively, with US features guiding the choice between repeat biopsy and diagnostic surgery.

Active surveillance (AS) has been widely adopted as an alternative to immediate surgery owing to the indolent nature and favorable outcomes of papillary thyroid microcarcinoma (PTMC). AS is generally recommended for tumors measuring ≤1 cm without aggressive cytological subtypes, risk of gross extrathyroidal extension (ETE), lymph node metastasis (LNM), or distant metastasis. AS requires careful patient selection based on various patient and tumor characteristics, and ultrasound (US) findings. Moreover, during AS, regular US is performed to monitor any signs of tumor progression, including tumor growth, new US features of potential gross ETE, and LNM. Therefore, appropriate imaging-based assessment plays a crucial role in determining whether AS or surgery should be pursued. However, detailed recommendations concerning US evaluation are currently insufficient, necessitating the formulation of this guideline. The Korean Society of Thyroid Radiology has developed a consensus statement for low-risk PTMC, covering US assessment methods when considering AS as a management option and conducting follow-up imaging tests during AS. This guideline aims to provide optimal scientific evidence and expert opinion consensus regarding a standardized US-based assessment protocol for low-risk PTMC.