International Expert Consensus on US Lexicon for Thyroid Nodules.

Multiple US-based systems for risk stratification of thyroid nodules are in use worldwide. Unfortunately, the malignancy probability assigned to a nodule varies, and terms and definitions are not consistent, leading to confusion and making it challenging to compare study results and craft revisions. Consistent application of these systems is further hampered by interobserver variability in identifying the sonographic features on which they are founded. In 2018, an international multidisciplinary group of 19 physicians with expertise in thyroid sonography (termed the International Thyroid Nodule Ultrasound Working Group) was convened with the goal of developing an international system, tentatively called the International Thyroid Imaging Reporting and Data System, or I-TIRADS, in two phases: (phase I) creation of a lexicon and atlas of US descriptors of thyroid nodules and (phase II) development of a system that estimates the malignancy risk of a thyroid nodule. This article presents the methods and results of phase I. The purpose herein is to show what has been accomplished thus far, as well as generate interest in and support for this effort in the global thyroid community.

Development of a machine learning-based fine-grained risk stratification system for thyroid nodules using predefined clinicoradiological features.

OBJECTIVE: We constructed and validated a machine learning-based malignancy risk estimation model using predefined clinicoradiological features, and evaluated its clinical utility for the management of thyroid nodules. METHODS: In total, 5708 benign (n = 4597) and malignant (n = 1111) thyroid nodules were collected from 5081 consecutive patients treated in 26 institutions. Seventeen experienced radiologists evaluated nodule characteristics on ultrasonographic images. Eight predictive models were used to stratify the thyroid nodules according to malignancy risk; model performance was assessed via nested 10-fold cross-validation. The best-performing algorithm was externally validated using data for 454 thyroid nodules from a tertiary hospital, then compared to the Thyroid Imaging Reporting and Data System (TIRADS)-based interpretations of radiologists (American College of Radiology, European and Korean TIRADS, and AACE/ACE/AME guidelines). RESULTS: The area under the receiver operating characteristic (AUROC) curves of the algorithms ranged from 0.773 to 0.862. The sensitivities, specificities, positive predictive values, and negative predictive values of the best-performing models were 74.1-76.6%, 80.9-83.4%, 49.2-51.9%, and 93.0-93.5%, respectively. For the external validation set, the ElasticNet values were 83.2%, 89.2%, 81.8%, and 90.1%, respectively. The corresponding TIRADS values were 66.5-85.0%, 61.3-80.8%, 45.9-72.1%, and 81.5-90.3%, respectively. The new model exhibited a significantly higher AUROC and specificity than did the TIRADS risk stratification, although its sensitivity was similar. CONCLUSION: We developed a reliable machine learning-based predictive model that demonstrated enhanced specificity when stratifying thyroid nodules according to malignancy risk. This system will contribute to improved personalized management of thyroid nodules. KEY POINTS: • The area under the receiver operating characteristic (AUROC) curve, sensitivity, and specificity of our model were 0.914, 83.2%, and 89.2%, respectively (derived using the validation dataset). • Compared to the TIRADS values, the AUROC and specificity are significantly higher, while the sensitivity is similar. • An interactive version of our AI algorithm is at http://tirads.cdss.co.kr .

Diagnostic performance of the 2021 Korean thyroid imaging reporting and data system in pediatric thyroid nodules.

OBJECTIVES: To evaluate the diagnostic performance of 2021 K-TIRADS biopsy criteria for detecting malignant thyroid nodules in a pediatric population, making comparisons with 2016 K-TIRADS. METHODS: This retrospective study included pediatric patients with histopathologically confirmed diagnoses. The diagnostic performance of 2021 K-TIRADS was compared with that of 2016 K-TIRADS. Simulation studies were performed by changing biopsy cut-off sizes for K-TIRADS 5 to 1.0 cm (K-TIRADS5-1.0cm) and 0.5 cm (K-TIRADS5-0.5cm), and for K-TIRADS 4 to 1.0 cm (K-TIRADS4-1.0cm) and 1.0-1.5 cm (K-TIRADS4-1.0~1.5cm). Subgroup analysis was performed in small (< 1.5 cm) and large nodules (≥ 1.5 cm). RESULTS: Two hundred seventy-seven thyroid nodules (54.9% malignant) from 221 pediatric patients were analyzed. All simulated 2021 K-TIRADS showed higher accuracy than 2016 K-TIRADS. Compared with 2021 K-TIRADS5-1.0cm, 2021 K-TIRADS5-0.5cm showed lower specificity (51.6% vs. 47.9%; p = 0.004) but higher sensitivity (77.2% vs. 90.3%; p < 0.001) and accuracy (62.7% vs. 68.9%; p < 0.001). Compared with 2021 K-TIRADS4-1.0cm, 2021 K-TIRADS4-1.0~1.5cm showed higher specificity (44.9% vs. 47.9%; p = 0.018) without significant difference in other diagnostic measures. Compared with 2016 K-TIRADS, 2021 K-TIRADS (biopsy cut-offs, 0.5 cm for K-TIRADS 5; 1.0-1.5 cm for K-TIRADS 4) showed higher sensitivity (34.0% vs. 67.3%; p < 0.001) while maintaining specificity (89.4% vs. 88.2%; p = 0.790) in small nodules, and higher specificity (5.9% vs. 25.4%; p < 0.001) while maintaining sensitivity (100% vs. 98.7%; p = 0.132) in large nodules. CONCLUSIONS: In pediatric patients, 2021 K-TIRADS showed superior diagnostic accuracy to 2016 K-TIRADS, especially with a biopsy cut-off of 0.5 cm for K-TIRADS 5 and 1.0-1.5 cm for K-TIRADS 4. KEY POINTS: • All simulated 2021 K-TIRADS showed higher accuracy than 2016 K-TIRADS. • 2021 K-TIRADS with cut-off size for K-TIRADS 5 of 0.5 cm showed lower specificity but higher sensitivity and accuracy than that of 1.0 cm. • Compared with 2016 K-TIRADS, 2021 K-TIRADS (biopsy cut-offs, 0.5 cm for K-TIRADS 5; 1.0-1.5 cm for K-TIRADS 4) showed higher sensitivity while maintaining specificity in small nodules, and higher specificity while maintaining sensitivity in large nodules.

Diagnostic Performance of Five Adult-based US Risk Stratification Systems in Pediatric Thyroid Nodules.

Background The validation of adult-based US risk stratification systems (RSSs) in the discrimination of malignant thyroid nodules in a pediatric population remains lacking. Purpose To estimate and compare the diagnostic performance of pediatric US RSSs based on five adult-based RSSs in the discrimination of malignant thyroid nodules in a pediatric sample. Materials and methods Pediatric patients (age ≤18 years) with histopathologically confirmed US-detected thyroid nodules at a tertiary referral hospital between January 2000 and April 2020 were analyzed retrospectively. The diagnostic performance of US-based fine-needle aspiration biopsy (FNAB) criteria in thyroid cancer detection was estimated. The following sensitivity analyses were performed: (a) scenario 1: nodules smaller than 1 cm, with the highest category additionally biopsied; (b) scenario 2, application of American College of Radiology Thyroid Imaging Reporting and Data System nodule size cutoffs to other RSSs; (c) scenario 3, scenarios 1 and 2 together. Generalized estimating equations (GEEs) were used for estimation. Results A total of 277 thyroid nodules in 221 pediatric patients (median age, 16 years [interquartile range {IQR}, 13-17]; 172 female; 152 of 277 patients [55%] malignant) were analyzed. The GEE-estimated sensitivity and specificity ranged from 70% to 78% (104 to 119 of 152 patients, based on each reader's interpretation) and from 42% to 78% (49 of 124 patients to 103 of 125 patients). In scenario 1, the missed malignancy rate was reduced from 32%-38% (41 of 134 patients to 34 of 83 patients) to 15%-21% (eight of 59 patients to 28 of 127 patients). In scenario 2, the unnecessary biopsy rate was reduced from 35%-39% (60 of 176 patients to 68 of 175 patients) to 20%-34% (18 of 109 patients to 62 of 179 patients). The highest accuracy was noted in scenario 3 (range, 71%-81%; 199 of 277 patients to 216 of 262 patients). Conclusion The diagnostic performances of the fine-needle aspiration biopsy criteria of five adult-based risk stratification systems were acceptable in the pediatric population and were improved by applying the American College of Radiology Thyroid Imaging Reporting and Data System size cutoff for nodules 1 cm or larger and allowing biopsy of the highest category nodules smaller than 1 cm. © RSNA, 2022 Online supplemental material is available for this article.

Histopathological correlation of punctate echogenic foci on ultrasonography in papillary thyroid carcinoma.

PURPOSE: To investigate the pathological entities of punctate echogenic foci (PEF) by correlating PEF with histopathological features of papillary thyroid carcinoma (PTC). METHODS: This study included 121 consecutive patients who had undergone thyroidectomy for PTC. The inclusion criterion was entire tumor resection with a 3-mm thickness for histopathological examination. We assessed the presence and number (<5 or ≥5) of PEF defined as punctate hyperechoic foci within the solid component of nodules. All surgical tumor specimens were retrospectively reviewed for the presence of microcalcifications, including the psammomatous calcification, coarse microcalcification, and micro-ossification, and inspissated colloid. RESULTS: PEF were detected in 71 (58.7%) PTCs. Psammomatous calcifications, coarse microcalcifications, and inspissated colloids were more frequently found in PTCs with PEF than in those without (74.6%, 42.3%, and 46.5%, respectively, p ≤ 0.024). Any type of microcalcification was found in 90.1% of PTCs with PEF. Psammomatous calcifications, coarse microcalcifications, and inspissated colloids were independently associated with PEF (p ≤ 0.012). Psammomatous calcifications were found in all PTCs with a high number (≥5) of PEF. CONCLUSION: Microcalcifications were found in most PTCs with PEF and psammomatous calcification was the main pathological entity of PEF in PTC. Our study validates reliability of PEF as a predictor of microcalcifications in PTC.

Diagnostic performance of core needle biopsy as a first-line diagnostic tool for thyroid nodules according to ultrasound patterns: Comparison with fine needle aspiration using propensity score matching analysis.

OBJECTIVE: This study aimed to compare the diagnostic performance of core-needle biopsy (CNB) to fine-needle aspiration (FNA) as a first-line diagnostic tool in initially detected thyroid nodules, according to ultrasound (US) patterns. MATERIALS AND METHODS: This study included 778 consecutive nodules from 705 patients who underwent CNB from one institution and 627 nodules from 583 patients who underwent FNA from two institutions. Adjustments for significant differences in patients' characteristics were facilitated via propensity score matching. We compared the diagnostic performance of CNB and FNA for thyroid malignancy according to three diagnostic criteria for all nodules and the US patterns. RESULTS: A 1:1 matching of 469 patients yielded no significant differences between CNB and FNA for any covariates. CNB showed a significantly higher sensitivity for malignancy than FNA with any criterion (criterion 1: category VI, criterion 2: category V and VI, criterion 3: category IV, V and VI) in overall and high suspicion nodules (90.1-99.5% vs 69.7%-88.3%, all P-values < 0.001) and low/intermediate suspicion nodules, except criterion 1 (61.9%-100% vs 36.4%-45.5%, all P ≤ .016). In ROC curve analysis, the areas under the ROC curve of CNB were significantly higher than those for FNA with any criterion in overall and high suspicion nodules (P < .001) and in low/intermediate suspicion nodules, except criterion 1 (P ≤ .008). CNB had a slightly higher minor complication rate than FNA (0.7% vs 0%, P ≥ .069). CONCLUSION: Our study suggests that CNB has a complementary role as an alternative first-line diagnostic tool to FNA for the initial diagnosis of thyroid nodules when performed by an experienced operator.

Which ultrasound image plane is appropriate for evaluating the taller-than-wide sign in the risk stratification of thyroid nodules?

OBJECTIVES: This study aimed to determine the ultrasound (US) image plane appropriate for evaluating the taller-than-wide (TTW) sign in the risk stratification of thyroid nodules using the five widely used risk stratification systems (RSSs). METHODS: A total of 1905 consecutive thyroid nodules with final diagnoses were included. The TTW sign was prospectively assessed in the transverse and longitudinal US image planes. The diagnostic performances of the TTW sign and biopsy criteria by the RSSs for malignancy were compared by sensitivity, specificity, and receiver operating characteristic curve analysis between the two criteria of TTW signs according to image planes (criterion 1, transverse plane; criterion 2, either transverse or longitudinal plane). RESULTS: Of all 1905 nodules, 1481 (77.7%) were benign and 424 (22.3%) were malignant. The criteria 1 and 2 of TTW signs had similar sensitivities (37.5% and 38.7%) and specificities (94.8% and 94.4%) with minimal differences, and the area under the curve (AUC) of TTW signs for malignancy was not significantly different between criteria 1 and 2 (0.662 and 0.665, p = 0.158, respectively). The sensitivity, specificity, and AUC of biopsy criteria by the five RSSs were not significantly different between criteria 1 and 2 in nodules ≥ 1 cm (p ≥ 0.157, p ≥ 0.317, and p ≥ 0.198, respectively). CONCLUSIONS: The diagnostic performances of the TTW sign and biopsy criteria of the five RSSs were similar between criteria 1 and 2. TTW signs by criterion 1 (transverse plane) may be appropriate in the risk stratification of thyroid nodules. KEY POINTS: • The diagnostic performance of the taller-than-wide sign by ROC analysis was not significantly different between US image plane criteria (transverse plane vs. either transverse or longitudinal plane). • The diagnostic performances of biopsy criteria for malignancy by the five risk stratification systems were similar between the two taller-than-wide sign criteria. • The taller-than-wide sign using the transverse plane may be appropriate in the risk stratification of thyroid nodules.

Five-year follow-up results of thermal ablation for low-risk papillary thyroid microcarcinomas: systematic review and meta-analysis.

OBJECTIVES: Confidence in long-term treatment results of thermal ablation for papillary thyroid microcarcinoma (PTMC) is required in comparison with active surveillance. The objective of this meta-analysis is to report 5-year follow-up results of thermal ablation for PTMC. METHODS: Ovid MEDLINE and EMBASE databases were searched through May 30, 2020, for studies reporting outcomes in patients with PTMC treated with thermal ablation and followed up for at least 5 years. Data were extracted and methodological quality was assessed independently by two radiologists according to the PRISMA guidelines. RESULTS: Three studies, involving 207 patients with 219 PTMCs, met the inclusion criteria through database searches. None of these patients experienced local tumor recurrence, lymph node metastasis, or distant metastasis or underwent delayed surgery during a mean pooled 67.8-month follow-up. Five new tumors appeared in the remaining thyroid gland of four patients, with four of these tumors successfully treated by repeat thermal ablation. The pooled mean major complication rate was 1.2%, with no patient experiencing life-threatening or delayed complications. CONCLUSIONS: Thermal ablation is an excellent local tumor control method in patients with low-risk PTMC, with low major complication rates at 5 years. KEY POINTS: • No local tumor recurrence, lymph node metastasis, or distant metastasis was noted by thermal ablation during follow-up of 5 years and none underwent delayed surgery. • The pooled mean major complication rate was 1.2%.

Radiofrequency Ablation of Benign Thyroid Nodules: Recommendations from the Asian Conference on Tumor Ablation Task Force - Secondary Publication.

Radiofrequency ablation (RFA) is a thermal ablation technique widely used for the management of benign thyroid nodules. To date, five academic societies in various countries have reported clinical practice guidelines, opinion statements, or recommendations regarding the use of thyroid RFA. However, despite some similarities, there are also differences among the guidelines, and a consensus is required regarding safe and effective treatment in Asian countries. Therefore, a task force was organized by the guideline committee of the Asian Conference on Tumor Ablation with the goal of devising recommendations for the clinical use of thyroid RFA. The recommendations in this article are based on a comprehensive analysis of the current literature and the consensus opinion of the task force members.

Ultrasound malignancy risk stratification of thyroid nodules based on the degree of hypoechogenicity and echotexture.

OBJECTIVES: The ultrasound (US) lexicon of nodule echogenicity and echotexture is one of the major differences among various risk stratification systems of thyroid nodules. This study aimed to stratify the US malignancy risk of thyroid nodules based on their degree of hypoechogenicity and echotexture. MATERIAL AND METHODS: This retrospective study included a total of 2255 consecutive thyroid nodules (≥ 1 cm) with final diagnoses (malignancy rate, 13%) from 2011 to 2016. Thyroid nodules were stratified according to the US degree of hypoechogenicity (mild, moderate, or marked hypoechogenicity) and echotexture (homogeneous vs. heterogeneous). The calculated malignancy risk was compared between each category. RESULTS: There was no significant difference of malignancy risk between the homogeneous markedly hypoechoic and moderately hypoechoic nodules (p ≥ .18). However, the malignancy risks of markedly and moderately hypoechoic nodules were significantly higher than those of mildly hypoechoic nodules (p < .001). Heterogeneous predominantly hypoechoic thyroid nodules showed a significantly higher malignancy risk than predominantly iso- or hyperechoic thyroid nodules (p < .001). There were no significant differences of malignancy risk between heterogeneous predominantly hypoechoic and homogeneous hypoechoic nodules according to the degree of hypoechogenicity (p ≥ .12) and between heterogeneous predominantly iso- or hyperechoic nodules and homogeneous iso- or hyperechoic thyroid nodules (p = .36). CONCLUSIONS: The malignancy risk of nodule hypoechogenicity is stratified as mild vs. moderate to marked hypoechogenicity, and the malignancy risk of nodules with heterogeneous echotexture is stratified by the predominant echogenicity of the nodules. KEY POINTS: • Thyroid nodule echogenicity is categorized as marked, moderate, or mild hypoechogenicity and iso- or hyperechogenicity with the reference standard of adjacent thyroid tissue and anterior neck muscles. • The malignancy risk of thyroid nodule echogenicity is stratified as iso- or hyperechoic vs. mild vs. moderate or marked hypoechogenicity. • The malignancy risk of nodules with heterogeneous echotexture is stratified by the predominant echogenicity.

Diagnostic Performance of Practice Guidelines for Thyroid Nodules: Thyroid Nodule Size versus Biopsy Rates.

Background The diagnostic performance and unnecessary biopsy rates for evaluation of thyroid nodules varies among the current society guidelines. We hypothesized that diagnostic performance and unnecessary biopsy rates of different guidelines are largely determined by different thyroid size thresholds used as cutoff values that determine when to biopsy a thyroid nodule. Purpose To compare the malignancy risk, diagnostic performance, and unnecessary biopsy rates of three guidelines and evaluate the changes according to the nodule size cutoff for biopsy. Materials and Methods This retrospective study included 3323 consecutive thyroid nodules from 3190 patients between January 2013 and December 2013. US features were reviewed according to the American Thyroid Association (ATA), Korean Thyroid Association/Korean Society of Thyroid Radiology (KTA/KSThR), and American College of Radiology (ACR) guidelines. The diagnostic performance and unnecessary biopsy rates were calculated. The size cutoff of ATA and KTA/KSThR guidelines was varied and diagnostic performance and unnecessary biopsy rates were calculated and compared by using the generalized estimating equations method. Results A total of 856 (25.8%) thyroid nodules were diagnosed as malignant after surgical excision or biopsy. The highest sensitivity was observed with the KTA/KSThR guideline (93.5% [300 of 321]), followed by the ATA (92.5% [297 of 321]) and ACR guidelines (60.1% [193 of 321]). The highest specificity (75.2% [1216 of 1617], P < .001) with lowest unnecessary biopsy rate (20.7% [401 of 1938]) was observed with the ACR guideline. When the low-suspicion category in the ATA guideline modeled 2.5 cm instead of 1.5 cm as the size for biopsy, the unnecessary biopsy rate decreased to 43.6% (845 of 1938, 2.5-cm cutoff) compared with 55.1% (1068 of 1938, 1.5-cm cutoff) (P < .001). For the KTA/KSThR guidelines, the unnecessary biopsy rate decreased to 36.4% (706 of 1938, 2.5-cm cutoff) compared with 59.5% (1153 of 1938, 1.5-cm cutoff) (P < .001). Conclusion The diagnostic performance and unnecessary biopsy rates of the American Thyroid Association and the Korean Thyroid Association/Korean Society of Thyroid Radiology guidelines are strongly influenced by nodule size cutoff. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Foley in this issue.

Similarities and Differences Between Thyroid Imaging Reporting and Data Systems.

OBJECTIVE. The purposes of this study were to identify the similarities and differences among the Korean Thyroid Imaging Reporting and Data System (TIRADS), American College of Radiology (ACR) TI-RADS, and European TIRADS and to compare the diagnostic performance of sonographic fine-needle aspiration (FNA) criteria for detecting malignant thyroid nodules. MATERIALS AND METHODS. This study included 2274 consecutively evaluated thyroid nodules 1 cm or larger in 1836 patients with final diagnoses from January 2011 to December 2016. US features of the nodules were retrospectively reviewed and classified according to three published guidelines from international societies. We compared the US lexicons, categories, and diagnostic performance of the FNA criteria for malignant nodules among the three reporting systems. RESULTS. Of the 2274 thyroid nodules, 1974 (86.8%) were benign and 300 (13.2%) were malignant; 93.7% of all malignancies were papillary carcinoma. Most of the US lexicons were similar among the three systems except for the definition of echogenicity of a nodule of mixed echogenicity in European TIRADS. Although the categories had strong correlations (r = 0.777-0.877, all p < 0.001) among the three systems, significant differences were observed in categories 5, 4, and 3 of nodules (all p < 0.001) and in the sensitivity, specificity, and rate of unnecessary FNA of the FNA criteria for malignancy (all p < 0.001). CONCLUSION. Although the three systems had similarities in most US lexicons, significant differences were observed in the classified categories and diagnostic performance of the FNA criteria for malignancy.

US Fine-Needle Aspiration Biopsy for Thyroid Malignancy: Diagnostic Performance of Seven Society Guidelines Applied to 2000 Thyroid Nodules.

Purpose To compare the diagnostic performance of ultrasonography (US)-based fine-needle aspiration biopsy (FNAB) criteria from seven international societies in the detection of thyroid malignancy. Materials and Methods This study included a total of 2000 consecutive thyroid nodules (≥1 cm) in 1802 patients with final diagnoses from January 2010 to May 2011. US features of the thyroid nodules were retrospectively reviewed and were classified according to the categories defined by the seven international society guidelines. The diagnostic performance of US-based FNAB criteria in the detection of thyroid malignancy and unnecessary FNAB rates were calculated and compared by using a generalized estimating equation method. Results Of the 2000 thyroid nodules, 1546 (78.3%) were benign and 454 (22.7%) were malignant, with papillary carcinoma comprising 85.5% of all malignancies. The Korean Thyroid Association/Korean Society of Thyroid Radiology (KTA/KSThR) (94.5%), National Comprehensive Cancer Network (NCCN) (92.5%), and American Thyroid Association (ATA) (89.6%) guidelines were more sensitive than those of the American Association of Clinical Endocrinologists/American College of Endocrinology/Associazione Medici Endocrinologi (AACE/ACE/AME) (80.4%), American College of Radiology (ACR) (74.7%), French Society of Endocrinology (FSE) (72.7%), and Society of Radiology in Ultrasound (SRU) (70.9%) (P < .001), while the latter guidelines had higher specificity (P < .001). The rate of unnecessary FNAB was lowest with the ACR guidelines (25.3%), followed by the FSE (29.1%), AACE/ACE/AME (32.5%), SRU (45.2%), ATA (51.7%), NCCN (54.0%), and KTA/KSThR (56.9%) guidelines. Conclusion Because the diagnostic performance of US-based FNAB criteria varies according to the individual international society guidelines, clinicians should be aware of the strengths and weaknesses of US-based FNAB criteria in the management of thyroid nodules. © RSNA, 2018 Online supplemental material is available for this article.

Acute invasive fungal rhinosinusitis: MR imaging features and their impact on prognosis.

PURPOSE: Acute invasive fungal rhinosinusitis (AIFRS) is a life-threatening disease that is difficult to diagnose. Its overall imaging features have not been evaluated and the prognostic impact is unclear. The purpose of our study was to present MR imaging features and their impact on prognosis of AIFRS. METHODS: MR images and clinical records of 23 patients with AIFRS were retrospectively evaluated to identify the imaging features and to determine the factors affecting patients' survival. A multivariable Cox proportional hazard model was used to estimate the hazard ratio of the prognostic factors, and Kaplan-Meier survival curves were compared by using a log-rank test. RESULTS: All cases showed extra-sinonasal involvement and the orbit was the most common (65.2%, 15/23) location. The lesion enhancement pattern was classified into lack of contrast enhancement (LoCE) (47.8%, 11/23) and homogeneous (34.8%, 8/23) and heterogeneous (17.4%, 4/23) enhancement. Although LoCE showed variable signal intensity (SI), homogeneously or heterogeneously enhancing lesions showed exclusively low SI (100%, 12/12) on T2WI. Among various clinical and imaging factors, LoCE was correlated with coagulation necrosis, probably provoked by numerous fungal hyphae, and was found to be a sole independent prognostic factor for disease-specific mortality (hazard ratio = 16.819; 95% CI, 1.646-171.841, p = 0.017). In addition, patients with LoCE showed worse survival than patients without LoCE (p = 0.008). CONCLUSION: AIFRS showed frequent extra-sinonasal involvement and variable MR enhancement patterns. An enhancement pattern of LoCE was seen in about half of the cases and was a unique prognostic factor among the various clinico-radiologic factors.

Treatment Efficacy and Safety of Ethanol Ablation for Thyroglossal Duct Cysts: A Comparison with Surgery.

OBJECTIVE: To compare the efficacy and safety of ethanol ablation (EA) for thyroglossal duct cyst (TGDC) against surgery. METHODS: This study included 345 patients (289, surgery; 56, EA) treated for TGDC at four institutions between May 2005 and June 2014. Surgery (whole surgery and Sistrunk operation which is the current standard surgical method) and EA were compared with respect to the treatment failure and complication rates. The cost of EA and surgery was also compared. The Cox regression hazard model and linear regression were used for the adjustment of covariates. RESULTS: EA demonstrated higher treatment failures (19.6% vs. 2.4%, p < 0.001[whole surgery] and 1.2%, p = 0.004 [Sistrunk operation]), but fewer complications (1.8% vs. 10.0%, p = 0.04 [whole surgery] and 10.2%, p = 0.06 [Sistrunk operation]), and lower cost (₩423,801 vs. ₩1,435,707 [whole surgery]) than surgery. EA achieved 85.7% of treatment success up to second session. The mean volume reduction rate after EA was 82.3% at last follow-up. Young age and EA were correlated with treatment failure (p = 0.01 and 0.001, respectively). CONCLUSION: Both surgery and EA had acceptable treatment efficacy in the management of TGDC. Although there is a higher likelihood of treatment failure with EA, it has a better safety profile than surgery. KEY POINTS: • Both surgery and ethanol ablation show acceptable treatment efficacy for TGDC. • Considering treatment failure, surgery manages TGDC more effectively than EA. • EA is safer than surgery and presents no major complications. • EA could be an alternative treatment for TGDC in selected patients.

Radiofrequency ablation of small follicular neoplasms: initial clinical outcomes.

BACKGROUND: In thyroid gland, radiofrequency ablation (RFA) has been applied to both recurrent cancers and benign nodules, although, according to the American Thyroid Association (ATA) and the Korean Society of Thyroid Radiology (KSThR) guidelines, surgery is the first-line treatment for follicular neoplasm. However, it has been argued that follicular neoplasm with lower risk of malignancy can be managed by close follow-up. In this study, we evaluated the effectiveness of RFA of small follicular neoplasms, examining reductions in volume and related clinical problems, and making observations over long-term follow-up. METHODS: We evaluated 10 follicular neoplasms in 10 patients who were treated with RF ablation between 2009 and 2011. A RF generator and an 18-gauge internally cooled electrode were used to perform complete ablation of the whole nodules. Changes in nodules or ablated zones on follow-up ultrasound, and complications during and after RF ablation were evaluated. RESULTS: The mean follow-up period was 66.4 ± 5.1 months (range: 60-76 months). In eight patients, single session of RF ablation was sufficient, while two patients required two sessions. There was a significant reduction in the mean volume (99.5 ± 1.0%) of lesions, with eight ablated lesions (8/10, 80%) disappearing completely on follow-up. No recurrences were found in any ablated zones at last follow-up. Transient mild neck pain (n = 6) occurred during the procedure without requiring any medication. CONCLUSION: In addition to active surveillance, RF ablation may be an effective and safe alternative for the management of patients with small (<2 cm) follicular neoplasm suspected on thyroid biopsy and who strongly refuse surgery.

Radiofrequency ablation of low-risk small papillary thyroidcarcinoma: preliminary results for patients ineligible for surgery.

PURPOSE: The purpose of this study is to retrospectively evaluate the outcomes of radiofrequency ablation (RFA) of low-risk small papillary thyroid carcinomas (PTCs) in patients who were ineligible for surgery. MATERIALS AND METHODS: Between 2005 and 2009, six PTCs (mean diameter, 0.92 cm; range, 0.6-1.3 cm) in six patients were treated with RFA by three radiologists in two hospitals. The inclusion criteria for this study were (1) pathologically confirmed PTC without cytological aggressiveness, (2) single PTC without extrathyroidal extension, (3) no metastatic tumours and (4) ineligibility for surgery. RFA was performed using a radiofrequency generator and an 18-gauge internally cooled electrode. The medical records were reviewed and analysed, focussing on the procedural profiles of RFA, symptoms and complications during and after RFA, and changes in tumours on follow-up ultrasonography. RESULTS: Before and after RFA, the results of thyroid function tests were normal in all patients. During 48.5 ± 12.3 months (range, 36-65 months) of follow-up, along with a significant reduction in the mean volume (98.5 ± 3.3%), four ablation zones (4/6, 66.7%) completely disappeared. Two ablation zones exhibited only small calcified residues with nearly complete disappearance of the corresponding non-calcified solid portions, and in one of them, malignant cells were absent as assessed by fine-needle aspiration and core-needle biopsy. Transient hypertension with mild headache (n = 1) and mild neck pain (n = 1) developed during the procedure and subsided without any treatment. CONCLUSION: Besides surgery and active surveillance, which are conflicting currently used management plans, RFA might represent an effective and a safe alternative for managing low-risk small PTCs, especially in patients ineligible for surgery.

Ultrasound-Based Risk Stratification for Malignancy in Thyroid Nodules: A Four-Tier Categorization System.

OBJECTIVES: The purpose of this study was to stratify the malignancy risk of US features, with an emphasis on nodule echogenicity. METHODS: A total of 1,058 nodules of 824 consecutive patients (236 malignant and 822 benign) were included in this study. Malignancy risk of each nodule was analyzed according to US features, with an emphasis on nodule echogenecity, and was stratified into 4-tier categories. RESULTS: In multivariate analysis, isoechogenicity, indistinct margin, non-solid internal content, and parallel orientation were predictive of benign nodules (P < 0.002), while hypoechogenicity, marked hypoechogenicity, spiculated/microlobulated margin, solid content, nonparallel orientation (taller than wide), microcalcification, and macrocalcification were predictive of malignancy (P ≤ 0.037). Although the presence of US features associated with malignancy was significantly predictive of malignancy in hypoechoic and markedly hypoechoic nodules (P ≤ 0.004), it was not associated with malignancy in isoechoic or hyperechoic nodules. Thyroid nodules could be stratified into four categories according to the malignancy risk: benign (risk 0%), probably benign (risk ≤ 5%), indeterminate (risk > 5 and < 50%), and suspicion of malignancy (risk > 50%). CONCLUSIONS: The US-based four-tier categorization system will be useful for predicting the risk of malignancy and decisions regarding FNA for thyroid nodules. KEY POINTS: • No US feature was predictive of malignancy in isoechoic nodules. • Isoechoic nodules without calcification can be included in the probably benign category. • We suggest a four-tier categorization stratified primarily by nodule echogenecity. • The four-tier categorization of thyroid nodules will be useful for FNA decisions.

Malignancy risk stratification and subcategorization of K-TIRADS intermediate suspicion thyroid nodules: a retrospective multicenter study.

PURPOSE: This study aimed to develop the ultrasonography (US) criteria for risk stratification of the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) 4 nodules, and to evaluate the diagnostic yield of a modified biopsy criterion in a multicenter cohort. METHODS: In total, 1,542 K-TIRADS 4 nodules (≥1 cm) were included in the study. US criteria for the subcategorization of K-TIRADS 4 nodules were developed based on high-risk US features. The diagnostic yields and false referral rates of biopsy criterion 1 (size cut-off of 1 cm), biopsy criterion 2 (size cut-off of 1.5 cm), and modified biopsy criterion 3 (size cut-off of 1 cm for K-TIRADS 4B and 1.5 cm for K-TIRADS 4A) were evaluated. RESULTS: The five high-risk US features (solid composition, marked hypoechogenicity, macrocalcification, punctate echogenic foci, and irregular margin) independently increased the malignancy risk of the K-TIRADS 4 nodules (P<0.001). The K-TIRADS 4 nodules could be subcategorized into higher- and lower-risk subcategories according to the number of high-risk US features: K-TIRADS 4B (≥2 US features) and K-TIRADS 4A (≤1 US feature). The modified biopsy criterion increased the diagnostic yield by 7.8% compared with criterion 2 and reduced the false referral rate by 15.3% compared with criterion 1 (P<0.001). CONCLUSION: The K-TIRADS 4 nodules were subcategorized as K-TIRADS 4B and K-TIRADS 4A based on high-risk US features. The modified biopsy criterion 3 showed a similar diagnostic yield and reduced false referral rate compared to criterion 1.