Diagnostic Performance of the Modified Korean Thyroid Imaging Reporting and Data System for Thyroid Malignancy: A Multicenter Validation Study

Objective@#To evaluate the diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System (K-TIRADS), and compare it with the 2016 version of K-TIRADS using the Thyroid Imaging Network of Korea. @*Materials and Methods@#Between June and September 2015, 5708 thyroid nodules (≥ 1.0 cm) from 5081 consecutive patients who had undergone thyroid ultrasonography at 26 institutions were retrospectively evaluated. We used a biopsy size threshold of 2 cm for K-TIRADS 3 and 1 cm for K-TIRADS 4 (modified K-TIRADS 1) or 1.5 cm for K-TIRADS 4 (modified K-TIRADS 3). The modified K-TIRADS 2 subcategorized the K-TIRADS 4 into 4A and 4B, and the cutoff sizes for the biopsies were defined as 1 cm for K-TIRADS 4B and 1.5 cm for K-TIRADS 4A. The diagnostic performance and the rate of unnecessary biopsies of the modified K-TIRADS for detecting malignancy were compared with those of the 2016 K-TIRAD, which were stratified by nodule size (with a threshold of 2 cm). @*Results@#A total of 1111 malignant nodules and 4597 benign nodules were included. The sensitivity, specificity, and unnecessary biopsy rate of the benign nodules were 94.9%, 24.4%, and 60.9% for the 2016 K-TIRADS; 91.0%, 39.7%, and 48.6% for the modified K-TIRADS 1; 84.9%, 45.9%, and 43.5% for the modified K-TIRADS 2; and 76.1%, 50.2%, and 40.1% for the modified K-TIRADS 3. For small nodules (1–2 cm), the diagnostic sensitivity of the modified K-TIRADS decreased by 5.2–25.6% and the rate of unnecessary biopsies reduced by 19.2–32.8% compared with those of the 2016 K-TIRADS (p 2 cm), the modified K-TIRADSs maintained a very high sensitivity for detecting malignancy (98%). @*Conclusion@#The modified K-TIRADSs significantly reduced the rate of unnecessary biopsies for small (1–2 cm) nodules while maintaining a very high sensitivity for malignancy for large (> 2 cm) nodules.

2020 Imaging Guidelines for Thyroid Nodules and Differentiated Thyroid Cancer: Korean Society of Thyroid Radiology

Imaging plays a key role in the diagnosis and characterization of thyroid diseases, and the information provided by imaging studies is essential for management planning. A referral guideline for imaging studies may help physicians make reasonable decisions and minimize the number of unnecessary examinations. The Korean Society of Thyroid Radiology (KSThR) developed imaging guidelines for thyroid nodules and differentiated thyroid cancer using an adaptation process through a collaboration between the National Evidence-based Healthcare Collaborating Agency and the working group of KSThR, which is composed of radiologists specializing in thyroid imaging. When evidence is either insufficient or equivocal, expert opinion may supplement the available evidence for recommending imaging. Therefore, we suggest rating the appropriateness of imaging for specific clinical situations in this guideline.

Diagnostic Performance of the Modified Korean Thyroid Imaging Reporting and Data System for Thyroid Malignancy: A Multicenter Validation Study

Objective@#To evaluate the diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System (K-TIRADS), and compare it with the 2016 version of K-TIRADS using the Thyroid Imaging Network of Korea. @*Materials and Methods@#Between June and September 2015, 5708 thyroid nodules (≥ 1.0 cm) from 5081 consecutive patients who had undergone thyroid ultrasonography at 26 institutions were retrospectively evaluated. We used a biopsy size threshold of 2 cm for K-TIRADS 3 and 1 cm for K-TIRADS 4 (modified K-TIRADS 1) or 1.5 cm for K-TIRADS 4 (modified K-TIRADS 3). The modified K-TIRADS 2 subcategorized the K-TIRADS 4 into 4A and 4B, and the cutoff sizes for the biopsies were defined as 1 cm for K-TIRADS 4B and 1.5 cm for K-TIRADS 4A. The diagnostic performance and the rate of unnecessary biopsies of the modified K-TIRADS for detecting malignancy were compared with those of the 2016 K-TIRAD, which were stratified by nodule size (with a threshold of 2 cm). @*Results@#A total of 1111 malignant nodules and 4597 benign nodules were included. The sensitivity, specificity, and unnecessary biopsy rate of the benign nodules were 94.9%, 24.4%, and 60.9% for the 2016 K-TIRADS; 91.0%, 39.7%, and 48.6% for the modified K-TIRADS 1; 84.9%, 45.9%, and 43.5% for the modified K-TIRADS 2; and 76.1%, 50.2%, and 40.1% for the modified K-TIRADS 3. For small nodules (1–2 cm), the diagnostic sensitivity of the modified K-TIRADS decreased by 5.2–25.6% and the rate of unnecessary biopsies reduced by 19.2–32.8% compared with those of the 2016 K-TIRADS (p 2 cm), the modified K-TIRADSs maintained a very high sensitivity for detecting malignancy (98%). @*Conclusion@#The modified K-TIRADSs significantly reduced the rate of unnecessary biopsies for small (1–2 cm) nodules while maintaining a very high sensitivity for malignancy for large (> 2 cm) nodules.

2020 Imaging Guidelines for Thyroid Nodules and Differentiated Thyroid Cancer: Korean Society of Thyroid Radiology

Imaging plays a key role in the diagnosis and characterization of thyroid diseases, and the information provided by imaging studies is essential for management planning. A referral guideline for imaging studies may help physicians make reasonable decisions and minimize the number of unnecessary examinations. The Korean Society of Thyroid Radiology (KSThR) developed imaging guidelines for thyroid nodules and differentiated thyroid cancer using an adaptation process through a collaboration between the National Evidence-based Healthcare Collaborating Agency and the working group of KSThR, which is composed of radiologists specializing in thyroid imaging. When evidence is either insufficient or equivocal, expert opinion may supplement the available evidence for recommending imaging. Therefore, we suggest rating the appropriateness of imaging for specific clinical situations in this guideline.

Concordance of Three International Guidelines for Thyroid Nodules Classified by Ultrasonography and Diagnostic Performance of Biopsy Criteria

Revisiting Rupture of Benign Thyroid Nodules after Radiofrequency Ablation: Various Types and Imaging Features

BACKGROUND: To evaluate the imaging features, clinical manifestations, and prognosis of patients with thyroid nodule rupture after radiofrequency ablation (RFA).METHODS: The records of 12 patients who experienced thyroid nodule rupture after RFA at four Korean thyroid centers between March 2010 and July 2017 were retrospectively reviewed. Clinical data evaluated included baseline patient characteristics, treatment methods, initial presenting symptoms, imaging features, treatment, and prognosis.RESULTS: The most common symptoms of post-RFA nodule rupture were sudden neck bulging and pain. Based on imaging features, the localization of nodule rupture was classified into three types: anterior, posterolateral, and medial types. The anterior type is the most often, followed by posterolateral and medial type. Eight patients recovered completely after conservative treatment. Four patients who did not improve with conservative management required invasive procedures, including incision and drainage or aspiration.CONCLUSION: Thyroid nodule rupture after RFA can be classified into three types based on its localization: anterior, posterolateral, and medial types. Because majority of thyroid nodule ruptures after RFA can be managed conservatively, familiarity with these imaging features is essential in avoiding unnecessary imaging workup or invasive procedures.

Ethanol Ablation of the Thyroid Nodules: 2018 Consensus Statement by the Korean Society of Thyroid Radiology

Minimally invasive treatment of symptomatic thyroid nodules is now commonplace. Ethanol ablation (EA) of thyroid cystic nodules has been performed since the 1990s, but there is no global consensus or guideline. Although various limitations of EA have been described, recommendations for practical application are necessary. Therefore, the Task Force Committee of the Korean Society of Thyroid Radiology initiated the present consensus statement and here we provide recommendations for the role of EA in the management of symptomatic thyroid nodules. These recommendations are based on evidence to date from the literature and expert opinion.

2017 Thyroid Radiofrequency Ablation Guideline: Korean Society of Thyroid Radiology

Thermal ablation using radiofrequency is a new, minimally invasive modality employed as an alternative to surgery in patients with benign thyroid nodules and recurrent thyroid cancers. The Task Force Committee of the Korean Society of Thyroid Radiology (KSThR) developed recommendations for the optimal use of radiofrequency ablation for thyroid tumors in 2012. As new meaningful evidences have accumulated, KSThR decided to revise the guidelines. The revised guideline is based on a comprehensive analysis of the current literature and expert consensus.

Efficacy and Safety of Radiofrequency Ablation for Benign Thyroid Nodules: A Prospective Multicenter Study

OBJECTIVE: To assess the efficacy and safety of thyroid radiofrequency (RF) ablation for benign thyroid nodules by trained radiologists according to a unified protocol in a multi-center study. MATERIALS AND METHODS: From 2010 to 2011, 345 nodules from 345 patients (M:F = 43:302; mean age ± SD = 46.0 ± 12.7 years, range = 15–79) who met eligibility criteria were enrolled from five institutions. At pre-ablation, the mean volume was 14.2 ± 13.2 mL (1.1–80.8 mL). For 12 months or longer after treatment, 276 lesions, consisting of 248 solid and 28 predominantly cystic nodules, were followed. All operators performed RF ablation with a cool-tip RF system and two standard techniques (a transisthmic approach and the moving-shot technique). Volume reduction at 12 months after RF ablation (the primary outcome), therapeutic success, improvement of symptoms as well as of cosmetic problems, and complications were evaluated. Multiple linear regression analysis was applied to identify factors that were independently predictive of volume reduction. RESULTS: The mean volume reduction at 12 months was 80.3% (n = 276) and at the 24-, 36-, 48-, and 60-month follow-ups 84.3% (n = 198), 89.2% (n = 128), 91.9% (n = 57), and 95.3% (n = 6), respectively. Our therapeutic success was 97.8%. Both mean symptom and cosmetic scores showed significant improvements (p < 0.001). The rate of major complications was 1.0% (3/276). Solidity and applied energy were independent factors that predicted volume reduction. CONCLUSION: Radiofrequency ablation performed by trained radiologists from multiple institutions using a unified protocol and similar devices was effective and safe for treating benign thyroid nodules.

Impact of Nodule Size on Malignancy Risk Differs according to the Ultrasonography Pattern of Thyroid Nodules

OBJECTIVE: To test whether the impact of thyroid-nodule size on the malignancy risk differs according to the ultrasonography (US) patterns of nodules. MATERIALS AND METHODS: This study is a post hoc analysis using data from the Thyroid Imaging Reporting and Data System (TIRADS) multicenter retrospective study which included 2000 consecutive thyroid nodules (≥ 1 cm) with final diagnoses. A total of 2000 consecutive thyroid nodules from 1802 patients (1387 women and 613 men; mean age, 51.2 ± 12.2 years) were enrolled in this study. The malignancy risk of the nodules was assessed according to the nodule size and US patterns (Korean-TIRADS). RESULTS: Overall, the malignancy risk did not increase as nodules enlarged. In high-suspicion nodules, the malignancy rate had no association with nodule size (p = 0.467), whereas in intermediate- or low-suspicion nodules there was a trend toward an increasing malignancy risk as the nodule size increased (p = 0.004 and 0.002, respectively). The malignancy rate of large nodules (≥ 3 cm) was higher than that of small nodules (< 3 cm) in intermediate-suspicion nodules (40.3% vs. 22.6%, respectively; p = 0.001) and low-suspicion nodules (11.3% vs. 7.0%, respectively; p = 0.035). There was a trend toward a decreasing risk and proportion of papillary carcinoma and an increasing risk and proportion of follicular carcinoma or other malignant tumors as nodule size increased (p < 0.001, respectively). CONCLUSION: The impact of nodule size on the malignancy risk differed according to the US pattern. A large nodule size (≥ 3 cm) showed a higher malignancy risk than smaller nodules in intermediate- and low-suspicion nodules.

Core Needle Biopsy of the Thyroid: 2016 Consensus Statement and Recommendations from Korean Society of Thyroid Radiology

Core needle biopsy (CNB) has been suggested as a complementary diagnostic method to fine-needle aspiration in patients with thyroid nodules. Many recent CNB studies have suggested a more advanced role for CNB, but there are still no guidelines on its use. Therefore, the Task Force Committee of the Korean Society of Thyroid Radiology has developed the present consensus statement and recommendations for the role of CNB in the diagnosis of thyroid nodules. These recommendations are based on evidence from the current literature and expert consensus.

Parathyroid ultrasonography: the evolving role of the radiologist

Previously, radiologists played a limited role in the treatment of parathyroid disease, primary focusing on the preoperative localization of parathyroid lesions responsible for hyperparathyroidism. But, the widespread use of high-resolution ultrasound has lead to the increasing detection of parathyroid incidentalomas (PTIs). Consequently, radiologists may be required to differentiate PTIs from thyroid lesions, which is most reliably accomplished through the fine needle aspiration-parathyroid hormone analysis. Various nonsurgical treatment modalities for hyperfunctioning parathyroid lesions have been developed with some efficacy. Especially for symptomatic nonfunctioning parathyroid cysts, simple aspiration is a first-line procedure for diagnosis and treatment, while ethanol ablation is a subsequent treatment modality for recurrent cases.

Radiofrequency versus Ethanol Ablation for Treating Predominantly Cystic Thyroid Nodules: A Randomized Clinical Trial

OBJECTIVE: To compare single-session radiofrequency ablation (RFA) and ethanol ablation (EA) for treating predominantly cystic thyroid nodules (PCTNs). MATERIALS AND METHODS: This single-blind, randomized trial was approved by the Institutional Review Board of two centers and informed consent was obtained from all patients before enrollment. Fifty patients with a single PCTN (cystic portion less than 90% and greater than 50%) were randomly assigned to be treated by either RFA (25 patients) or EA (25 patients) at two hospitals. The primary outcome was the tumor volume reduction ratio (%) at the six-month follow-up and the superiority margin was set at 13% (RFA minus EA). Analysis was performed primarily in an intention-to-treat manner. The secondary outcomes were the therapeutic success rate, improvement of symptomatic and cosmetic problems, and the number of major complications. RESULTS: The mean volume reduction was 87.5 ± 11.5% for RFA (n = 22) and 82.4 ± 28.6% for EA (n = 24) (p = 0.710; mean difference [95% confidence interval], 5.1% [-8.0 to 18.2]), indicating no significant difference. Regarding the secondary outcomes, therapeutic success (p = 0.490), mean symptom (p = 0.205) and cosmetic scores (p = 0.710) showed no difference. There were no major complications in either group (p > 0.99). CONCLUSION: The therapeutic efficacy of RFA is not superior to that of EA; therefore, EA might be preferable as the first-line treatment for PCTNs.

Comparison between Ultrasonography and Computed Tomography for Detecting the Pyramidal Lobe of the Thyroid Gland: A Prospective Multicenter Study

OBJECTIVE: To compare the detection rates of the pyramidal lobe of the thyroid gland (TPL) using ultrasonography (US) and computed tomography (CT) in a prospective multi-center study. MATERIALS AND METHODS: We enrolled 582 patients who underwent neck CT at six institutions. Each radiologist prospectively evaluated the presence and features of TPLs on thyroid US. Radiologists were divided into two groups according to their previous experience in detecting TPL on US or CT. The same radiologist also retrospectively assessed CT findings, blinded to the corresponding US findings. RESULTS: The pyramidal lobe of the thyroid glands were detected in 230 cases (39.5%) on US and in 276 cases (47.6%) on CT. The TPL detection rate at the six institutions ranged from 22.0% to 59% for US and from 34.1% to 59% using CT. There were significant differences between US and CT in the detection rate, length, anteroposterior diameter, volume, and superior extent of TPL (p < or = 0.027). The TPL detection rates on both US and CT (p < 0.001) differed significantly according to the experience level of the radiologists. When the CT result was used as a reference standard, the sensitivity, specificity, positive and negative predictive values, as well as the accuracy of US for TPL detection were 72.6%, 91.5%, 89.3%, 77.3%, and 82.1%, respectively. CONCLUSION: Our prospective multicenter study revealed that US could detect TPL with relatively high diagnostic accuracy compared to CT. Because the detection rate of TPL varied significantly according to the radiologists' level of experience, careful inspection is necessary to avoid imaging pitfalls and ensure appropriate evaluation of TPL on both US and CT.

Intralesional saline injection for effective ultrasound-guided aspiration of benign viscous cystic thyroid nodules

PURPOSE: We aimed to evaluate the efficacy and safety of vigorous saline injection for viscous cystic thyroid nodules. METHODS: Eighteen patients who underwent ultrasound-guided aspiration for viscous cystic thyroid nodules using a saline injection were included in our study. After failing to aspirate the cyst by the usual method, we vigorously injected saline into the cyst in multiple directions to break up and liquefy the viscous cystic contents to enable aspiration. The initial and the residual volume of the nodule were calculated, and the volume reduction rate and the time taken to perform the aspiration were recorded. RESULTS: The mean volume of the cystic nodules before aspiration was 11.0 mL (range, 1.2 to 26.0 mL), while the postaspiration volume was 4.2 mL (range, 0.2 to 14.5 mL). The mean aspirated volume was 63.7% of the initial volume. The mean procedure time was 12.4 minutes (range, 5 to 26 minutes). There were no significant complications related to the procedure. CONCLUSION: A vigorous saline injection followed by aspiration can be a useful method to aspirate viscous cystic thyroid nodules as a prestep for further intervention or simple management.

Core Needle Biopsy of Thyroid Nodules: Consensus Statement and Recommendations

Core needle biopsy is a complementary diagnostic method of fine needle aspiration for patients with thyroid nodules. The Task Force Committee of the Korean Society of Thyroid Radiology has developed recommendations for diagnosis of thyroid nodules and recurrent thyroid cancers using core needle biopsy. These recommendations are based on evidence from the current literature and expert consensus.

Image Reporting and Characterization System for Ultrasound Features of Thyroid Nodules: Multicentric Korean Retrospective Study

OBJECTIVE: The objective of this retrospective study was to develop and validate a simple diagnostic prediction model by using ultrasound (US) features of thyroid nodules obtained from multicenter retrospective data. MATERIALS AND METHODS: Patient data were collected from 20 different institutions and the data included 2000 thyroid nodules from 1796 patients. For developing a diagnostic prediction model to estimate the malignant risk of thyroid nodules using suspicious malignant US features, we developed a training model in a subset of 1402 nodules from 1260 patients. Several suspicious malignant US features were evaluated to create the prediction model using a scoring tool. The scores for such US features were estimated by calculating odds ratios, and the risk score of malignancy for each thyroid nodule was defined as the sum of these individual scores. Later, we verified the usefulness of developed scoring system by applying into the remaining 598 nodules from 536 patients. RESULTS: Among 2000 tumors, 1268 were benign and 732 were malignant. In our multiple regression analysis models, the following US features were statistically significant for malignant nodules when using the training data set: hypoechogenicity, marked hypoechogenicity, non-parallel orientation, microlobulated or spiculated margin, ill-defined margins, and microcalcifications. The malignancy rate was 7.3% in thyroid nodules that did not have suspicious-malignant features on US. Area under the receiver operating characteristic (ROC) curve was 0.867, which shows that the US risk score help predict thyroid malignancy well. In the test data set, the malignancy rates were 6.2% in thyroid nodules without malignant features on US. Area under the ROC curve of the test set was 0.872 when using the prediction model. CONCLUSION: The predictor model using suspicious malignant US features may be helpful in risk stratification of thyroid nodules.

Erratum: Image Reporting and Characterization System for Ultrasound Features of Thyroid Nodules: Multicentric Korean Retrospective Study

On page 110, the author (Won-Jin Moon)'s affiliation has been incorrectly marked as 6Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University, Seoul 143-729, Korea. The correct affiliation is 5Department of Radiology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul 143-729, Korea.

Radiofrequency Ablation of Benign Thyroid Nodules and Recurrent Thyroid Cancers: Consensus Statement and Recommendations

Radiofrequency ablation is a new non-surgical treatment modality for patients with benign thyroid nodules and recurrent thyroid cancers. The Task Force Committee of the Korean Society of Thyroid Radiology has developed recommendations for the treatment of benign thyroid nodules and recurrent thyroid cancers using radiofrequency ablation. These recommendations are based on evidence from the current literature and expert consensus.

Radiofrequency Ablation of Benign Thyroid Nodules and Recurrent Thyroid Cancers: Consensus Statement and Recommendations

Thermal ablation using radiofrequency is a new, minimally invasive modality employed as an alternative to surgery in patients with benign thyroid nodules and recurrent thyroid cancers. The Task Force Committee of the Korean Society of Thyroid Radiology has developed recommendations for the optimal use of radiofrequency ablation for thyroid nodules. These recommendations are based on a comprehensive analysis of the current literature, the results of multicenter studies, and expert consensus.