Subcategorization of intermediate suspicion thyroid nodules based on suspicious ultrasonographic findings

Purpose@#This study compared the malignancy risk of intermediate suspicion thyroid nodules according to the presence of suspicious ultrasonographic (US) findings. @*Methods@#From January 2014 to December 2014, 299 consecutive intermediate suspicion thyroid nodules in 281 patients (mean age, 50.6±12.5 years) with final diagnoses were included in this study. Two radiologists retrospectively reviewed the US findings and subcategorized the intermediate suspicion category into nodules without suspicious findings and nodules with suspicious findings, including punctate echogenic foci, nonparallel orientation, or irregular margins. The malignancy rates were compared between the two subcategory groups. @*Results@#Of the 299 intermediate suspicion thyroid nodules, 230 (76.9%) were subcategorized as nodules without suspicious findings and 69 (23.1%) as nodules with suspicious findings. The total malignancy rate was 33.4% (100/299) and the malignancy rate of nodules with suspicious findings was significantly higher than that of nodules without suspicious findings (47.8% vs. 29.1%, P=0.004). In nodules with suspicious findings, the most common suspicious finding was punctate echogenic foci (48/82, 58.5%) followed by nonparallel orientation (22/82, 26.8%) and irregular margins (12/82, 14.6%). Thirteen nodules had two suspicious findings simultaneously. A linearly increasing trend in the malignancy rate was observed according to the number of suspicious US findings (P for trend=0.001). @*Conclusion@#Intermediate suspicion thyroid nodules with suspicious findings showed a higher malignancy rate than those without suspicious findings. Further management guidelines for nodules with suspicious findings should differ from guidelines for nodules without suspicious findings, even in the same US category.

Delayed Cancer Diagnosis in Thyroid Nodules Initially Treated as Benign With Radiofrequency Ablation: Ultrasound Characteristics and Predictors for Cancer

Objective@#Regrowth after radiofrequency ablation (RFA) of symptomatic large thyroid nodules, initially treated as benign, sometimes turns out to be malignancies. This study aimed to assess the ultrasound (US) characteristics of thyroid nodules initially treated as benign with RFA and later diagnosed as cancers, predictive factors for cancers masquerading as benign, and methods to avoid RFA in these cancers. @*Materials and Methods@#We reviewed the medical records of 134 consecutive patients with 148 nodules who underwent RFA between February 2008 and November 2016 for the debulking of symptomatic thyroid nodules diagnosed as benign using US-guided biopsy. We investigated the pre-RFA characteristics of the thyroid nodules, changes at follow-up after RFA, and the final surgical pathology. @*Results@#Nodule regrowth after RFA was observed in 36 (24.3%) of the 148 benign nodules. Twenty-two of the 36 nodules were surgically removed, and malignancies were confirmed in seven (19.4% of 36). Of the 22 nodules removed surgically, pre-RFA median volume (range) was significantly larger for malignant nodules than for benign nodules: 22.4 (13.9–84.5) vs. 13.4 (7.3–16.8) mL (P = 0.04). There was no significant difference in the regrowth interval between benign and malignant nodules (P = 0.49). The median volume reduction rate (range) at 12 months was significantly lower for malignant nodules than for benign nodules (51.4% [0–57.8] vs. 83.8% [47.9–89.6]) (P = 0.01). The pre-RFA benignity of all seven malignant nodules was confirmed using two US-guided fine-needle aspirations (FNAs), except for one nodule, which was confirmed using US-guided core-needle biopsy (CNB). Regrown malignant nodules were diagnosed as suspicious follicular neoplasms by CNB. Histological examination of the malignant nodules revealed follicular thyroid carcinomas, except for one follicular variant, a papillary thyroid carcinoma. @*Conclusion@#Symptomatic large benign thyroid nodules showing regrowth or suboptimal reduction after RFA may have malignant potential. The confirmation of these nodules is better with CNB than with FNA.

Ultrasonographic characteristics of Hürthle cell neoplasms: prediction of malignancy

Purpose@#This study investigated the ultrasound (US) features of malignancy in patients with Hürthle cell neoplasms (HCNs) of the thyroid gland. @*Methods@#The present study included 139 HCNs that had undergone surgical excision at a single institution from 1996 to 2020 and had preoperative US images. The sonographic characteristics of HCNs were correlated with their pathological results. The US findings associated with malignancy were explored using logistic regression analysis, and the diagnostic performance and cutoff were assessed using receiver operating characteristic analysis. @*Results@#The most common US findings of HCNs were a solid content (76.3%), oval to round shape (100%), hypoechogenicity (70.5%), a smooth margin (95.0%), the halo sign (90.6%), and no calcifications (93.5%). HCNs were commonly smaller in pathologic measurements than in US measurements (smaller, same, and greater than US measurements in 60.4%, 21.6%, and 18.0% of HCNs, respectively; P3.35 cm might be used as a criterion to suggest malignancy. The size of HCNs often showed discrepancies between US and pathologic measurements.

What is the difference between the tall cell variant and the classic type of papillary thyroid carcinoma on ultrasonography?

Purpose@#The prevalence of the tall cell variant of papillary thyroid carcinoma (TCVPTC), which has a poor prognosis, has increased as its definition has been modified. We sought to investigate whether TCVPTC is different from the classic type on ultrasonography (US). @*Methods@#This study included 46 consecutive TCVPTC patients and 92 classic papillary thyroid carcinoma (PTC) patients who were confirmed surgically at the authors’ institution. The US findings and pathologic reports of these patients were retrospectively reviewed. US features based on the Korean Thyroid Imaging Reporting and Data System, preoperative US suspicion for lymph node metastasis, and the presence of capsular location were evaluated. @*Results@#Univariable and multivariable analyses identified that TCVPTC showed more frequent irregular tumor margin (odds ratio [OR], 6.62; 95% confidence interval [CI], 1.46 to 30.09; P=0.014) and capsular location (OR, 4.63; 95% CI, 1.49 to 14.41; P=0.008) than classic PTC. Capsular location was an independent predictor of TCVPTC for tumors less than or equal to 1.5 cm in size (OR, 4.23; 95% CI, 1.12 to 15.92; P=0.033). Irregular margin was an independent predictor of TCVPTC for tumors larger than 1.5 cm (OR, 10.46; 95% CI, 1.16 to 94.48; P=0.037). Extrathyroidal extension was not significantly different between the two groups. @*Conclusion@#The two key features of TCVPTC on US are frequent capsular location for tumors less than or equal to 1.5 cm in size and the higher likelihood of an irregular margin for tumors larger than 1.5 cm.

2021 Korean Thyroid Imaging Reporting and Data System and Imaging-Based Management of Thyroid Nodules: Korean Society of Thyroid Radiology Consensus Statement and Recommendations

Incidental thyroid nodules are commonly detected on ultrasonography (US). This has contributed to the rapidly rising incidence of low-risk papillary thyroid carcinoma over the last 20 years. The appropriate diagnosis and management of these patients is based on the risk factors related to the patients as well as the thyroid nodules. The Korean Society of Thyroid Radiology (KSThR) published consensus recommendations for US-based management of thyroid nodules in 2011 and revised them in 2016. These guidelines have been used as the standard guidelines in Korea. However, recent advances in the diagnosis and management of thyroid nodules have necessitated the revision of the original recommendations. The task force of the KSThR has revised the Korean Thyroid Imaging Reporting and Data System and recommendations for US lexicon, biopsy criteria, US criteria of extrathyroidal extension, optimal thyroid computed tomography protocol, and US follow-up of thyroid nodules before and after biopsy. The biopsy criteria were revised to reduce unnecessary biopsies for benign nodules while maintaining an appropriate sensitivity for the detection of malignant tumors in small (1–2 cm) thyroid nodules. The goal of these recommendations is to provide the optimal scientific evidence and expert opinion consensus regarding US-based diagnosis and management of thyroid nodules.

Feasibility of Adjustable Electrodes for Radiofrequency Ablation of Benign Thyroid Nodules

OBJECTIVE: The purpose of this study was to evaluate a novel radiofrequency ablation (RFA) application utilizing an adjustable electrode for treatment of benign thyroid nodules.MATERIALS AND METHODS: From April 2011 to December 2018, 21 patients underwent RFA treatment on 21 thyroid nodules, utilizing an 18-gauge internally cooled electrode equipped with a size adjustable active tip. The peripheral nodule portions were ablated with the moving-shot technique and a shorter active tip, and the nodule centers were ablated with the fixed technique and a longer active tip. We assessed parameters including characteristics of the treated nodules, use of variablesized active tips, volume reduction rate, therapeutic success rate, and post-procedural complications. The therapeutic success rate was defined as a > 50% volume reduction of the initial nodule volume at the 6- or 12-month follow-up.RESULTS: The treated thyroid nodules were large enough to cause symptoms (mean volume, 29.6 mL). Two types of active tips per session were used for all nodules. The mean volume reduction rate at the last follow-up was 68.3 ± 4.4% and our therapeutic success rate was 90.5%. Both symptoms and cosmetic scores decreased significantly. Minor complications in three patients were recorded during and after the procedure.CONCLUSION: This initial study demonstrated that an adjustable electrode for RFA of benign thyroid nodules effectively and safely resulted in volume reduction.

Ultrasound-Guided Core Needle Biopsy Techniques for Intermediate or Low Suspicion Thyroid Nodules: Which Method is Effective for Diagnosis?

OBJECTIVE: To retrospectively compare the diagnostic performances of two different ultrasound (US)-guided core needle biopsy (CNB) techniques for intermediate or low suspicion thyroid nodules. MATERIALS AND METHODS: Between August 2015 and December 2016, two different biopsy techniques were alternatively applied for 248 consecutive thyroid nodules, of which, 140 intermediate or low suspicion thyroid nodules were included in this study. In the first technique, two specimens included nodular tissue, nodular margin, and surrounding normal parenchyma (i.e., marginal target). In the second technique, two specimens were obtained from two different target areas, one for the marginal target and another for the intranodular target. The diagnostic performances of the two techniques to predict neoplasm and malignancy were compared. RESULTS: CNB was performed on 80 intermediate or low suspicion nodules (57.1%) using the first technique and on 60 (42.9%) using the second technique. The accuracy of the first technique for predicting neoplasm or malignancy was significantly higher than that of the second technique (100% vs. 93.3%, p = 0.032 for predicting neoplasm; 88.8% vs. 75.0%, p = 0.033 for predicting malignancy). The negative predictive value of the first technique for predicting malignancy was also significantly higher than that of the second technique (87.5% vs. 72.7%, p = 0.035). CONCLUSION: For intermediate or low suspicion thyroid nodules, US-guided CNB to obtain two specimens with marginal targets is more effective for diagnosing neoplasm or malignancy than is CNB for respective marginal and intranodular targets.

Effect of a Deep Learning Framework-Based Computer-Aided Diagnosis System on the Diagnostic Performance of Radiologists in Differentiating between Malignant and Benign Masses on Breast Ultrasonography

OBJECTIVE: To investigate whether a computer-aided diagnosis (CAD) system based on a deep learning framework (deep learning-based CAD) improves the diagnostic performance of radiologists in differentiating between malignant and benign masses on breast ultrasound (US). MATERIALS AND METHODS: B-mode US images were prospectively obtained for 253 breast masses (173 benign, 80 malignant) in 226 consecutive patients. Breast mass US findings were retrospectively analyzed by deep learning-based CAD and four radiologists. In predicting malignancy, the CAD results were dichotomized (possibly benign vs. possibly malignant). The radiologists independently assessed Breast Imaging Reporting and Data System final assessments for two datasets (US images alone or with CAD). For each dataset, the radiologists' final assessments were classified as positive (category 4a or higher) and negative (category 3 or lower). The diagnostic performances of the radiologists for the two datasets (US alone vs. US with CAD) were compared. RESULTS: When the CAD results were added to the US images, the radiologists showed significant improvement in specificity (range of all radiologists for US alone vs. US with CAD: 72.8–92.5% vs. 82.1–93.1%; p < 0.001), accuracy (77.9–88.9% vs. 86.2–90.9%; p = 0.038), and positive predictive value (PPV) (60.2–83.3% vs. 70.4–85.2%; p = 0.001). However, there were no significant changes in sensitivity (81.3–88.8% vs. 86.3–95.0%; p = 0.120) and negative predictive value (91.4–93.5% vs. 92.9–97.3%; p = 0.259). CONCLUSION: Deep learning-based CAD could improve radiologists' diagnostic performance by increasing their specificity, accuracy, and PPV in differentiating between malignant and benign masses on breast US.

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.

Complementary Role of Elastography Using Carotid Artery Pulsation in the Ultrasonographic Assessment of Thyroid Nodules: A Prospective Study

OBJECTIVE: The aim of this study was to evaluate the diagnostic performance of gray-scale ultrasonography (US), Doppler scan, and elastography using carotid artery pulsation in the diagnosis of thyroid nodules and to find a complementary role of elastography. MATERIALS AND METHODS: A total 197 thyroid nodules with 91 malignant and 106 benign pathologic results from 187 patients (41 males and 146 females; age range, 20–83 years; mean age, 49.4 years) were included in this prospective study. The gray-scale, Doppler US images, elastography with elasticity contrast index (ECI), and stiffness color were assessed. The diagnostic performances of each dataset were assessed in order to differentiate benign from malignant thyroid nodules. RESULTS: The optimal cut-off value of the ECI was 1.71. The area under receiver operating characteristic curve (Az value) was 0.821 for gray-scale US, 0.661 for the ECI, 0.592 for stiffness color, and 0.539 for Doppler US. The Az value for a combined assessment of gray-scale US and the ECI was higher than that for the gray-scale US alone; however, there was no statistical difference between the two (p = 0.219). The median ECI values of follicular thyroid carcinoma (FTC) and follicular variant of papillary thyroid carcinoma (FVPTC) were significantly lower than those of the other malignant lesions (p = 0.005). Meanwhile, the diffuse sclerosing variant of PTC and a metastatic nodule showed the two highest median values of the ECI. CONCLUSION: For differentiating thyroid nodules, the diagnostic performances of the combination of gray-scale US and elastography with the ECI were similar to, but not superior, to those of gray-scale US alone. FVPTC and FTC have a significantly lower ECI value than those of the other malignant lesions.

Columnar Cell Variant of Papillary Thyroid Carcinoma: Ultrasonographic and Clinical Differentiation between the Indolent and Aggressive Types

OBJECTIVE: To evaluate the ultrasonography (US) features and clinical characteristics of columnar cell variant of papillary thyroid carcinoma (CCV-PTC) that can predict disease progression. MATERIALS AND METHODS: Six cases of CCV-PTC were identified via surgical pathology analysis at our institution from 1994 to 2016. The histological, architectural, and cytological features met the diagnostic criteria of CCV-PTC. We reviewed the US features and clinicopathological findings in the six cases. RESULTS: An indolent clinical course was observed in four young female patients aged 27–34 years (median: 32 years), while two older patients aged 55 years or 70 years had an aggressive clinical course. All patients underwent total thyroidectomy and radioiodine therapy. The indolent group included patients with T1 and nodal metastasis, where the disease was not observed during the follow-up period (range: 8–17 years). On the other hand, a larger tumor size (1.8 cm and 6.0 cm), gross extrathyroidal extension to the muscle and lymph node, and distant metastasis were observed in the aggressive group. In one male patient, recurrence occurred immediately after operation, and this patient died 4 years after the diagnosis of thyroid cancer. Based on US, the individuals from the indolent group had a smooth margin, except for one. Both cases in the aggressive group had a microlobulated margin. CONCLUSION: Favorable prognosis in CCV-PTC is observed in young patients with T1 staging and demonstrates a smooth margin at US. These US findings might help exclude the same treatment as the aggressive type in the indolent type of CCV-PTC.

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.

Evaluation of Modified Core-Needle Biopsy in the Diagnosis of Thyroid Nodules

OBJECTIVE: Core needle biopsy (CNB) of the thyroid is an additional diagnostic method for non-diagnostic or indeterminate cytology samples. We sought to evaluate a new modified core biopsy technique and compare the concordance of its diagnosis with the final diagnosis of the surgically resected specimen. MATERIALS AND METHODS: A retrospective analysis was conducted on 842 patients who had a thyroid CNB with or without a previous fine-needle aspiration from August 2002 to March 2015; 38% of patients ultimately underwent thyroidectomy. We divided the patients into two groups for comparison: conventional group (n = 329) and new modified technique group (n = 513) that enabled sampling of not only the lesion but also the margin and surrounding parenchyma. The diagnostic conclusiveness of CNB and concordant rate with thyroidectomy was compared between the two groups. RESULTS: The overall diagnostic conclusiveness did not exhibit a significant increase (77% in the conventional technique group and 75% in the modified technique group, p = 0.408). In terms of the diagnostic concordance rate between CNB and thyroidectomy, no overall significant increase was observed (83% in the conventional technique group and 88% in the modified technique group, p = 0.194). However, only in follicular-patterned lesions (nodular hyperplasia, follicular neoplasm, and follicular variant of papillary thyroid carcinoma), a significant increase in the diagnostic concordance rate was observed (83% in the conventional group and 94% in the modified technique group, p = 0.033). CONCLUSION: Modified CNB technique can be beneficial for the accurate diagnosis of follicular-patterned thyroid lesions.

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.

Discrepancies between the ultrasonographic and gross pathological size of papillary thyroid carcinomas

PURPOSE: The goal of this study was to investigate the level of agreement between tumor sizes measured on ultrasonography (US) and in pathological specimens of papillary thyroid carcinomas (PTCs) and to identify the US characteristics contributing to discrepancies in these measurements. METHODS: We retrospectively reviewed the US findings and pathological reports of 490 tumors in 431 patients who underwent surgery for PTC. Agreement was defined as a difference of <20% between the US and pathological tumor size measurements. Tumors were divided by size into groups of 0.5-1 cm, 1-2 cm, 2-3 cm, and ≥3 cm. We compared tumors in which the US and pathological tumor size measurements agreed and those in which they disagreed with regard to the following parameters: taller-than-wide shape, infiltrative margin, echogenicity, microcalcifications, cystic changes in tumors, and the US diagnosis. RESULTS: The rate of agreement between US and the pathological tumor size measurements was 64.1% (314/490). Statistical analysis indicated that the US and pathological measurements significantly differed in tumors <1.0 cm in size (P=0.033), with US significantly overestimating the tumor size by 0.2 cm in such tumors (P<0.001). Cystic changes were significantly more frequent in the tumors where US and pathological tumor size measurements disagreed (P<0.001). CONCLUSION: Thyroid US may overestimate the size of PTCs, particularly for tumors <1.0 cm in size. This information may be helpful in guiding decision making regarding surgical extent.

Breast Imaging Reporting and Data System Category 3 Lesions Detected on Whole-Breast Screening Ultrasound / 한국유방암학회지

PURPOSE: This study assessed the incidence and cancer rate of probably benign lesions detected on bilateral whole-breast screening ultrasound (US), which corresponded to US Breast Imaging Reporting and Data System (BI-RADS) category 3, and evaluated the proper management of those lesions. METHODS: This study was approved by the Institutional Review Board in our institution, which waived informed patient consent. We retrospectively reviewed US images of 1,666 patients who underwent bilateral whole-breast screening US as a supplemental screening test to negative screening mammography or screening US only. The incidence, clinical course, and cancer rate of screening US-detected probably benign lesions corresponding to US BI-RADS category 3 were investigated, and the size and multiplicity of screening US-detected category 3 lesions were evaluated. RESULTS: Probably benign lesions corresponding to US BI-RADS category 3 were detected in 689 of 1,666 patients (41.4%) who underwent screening US. Among them, 653 had follow-up US images for at least 24 months, and among these 653, 190 (29.1%) had multiple bilateral category 3 lesions. Moreover, 539 of 1,666 patients (32.4%) had lesions ≤1 cm in size and 114 of 1,666 (6.8%) had lesions >1 cm (median, 0.82 cm; range, 0.3–4.2 cm). Four of the 653 patients (0.6%) showed suspicious interval changes and were categorized into BI-RADS category 4. Biopsy analysis confirmed only one lesion as invasive ductal carcinoma at the 6-month follow-up; another lesion was an intraductal papilloma and the remaining two were fibroadenomas. Overall cancer rate of the screening US-detected BI-RADS category 3 lesions was 0.2%. CONCLUSION: The incidence of category 3 lesions detected on screening US only was very high, but the cancer rate was very low. Therefore, in an average-risk population, routine screening US is preferable over short-term follow-up for BI-RADS category 3 lesions detected on whole-breast screening US.

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

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.

A comparison of lymphocytic thyroiditis with papillary thyroid carcinoma showing suspicious ultrasonographic findings in a background of heterogeneous parenchyma

PURPOSE: The aim of this study was to compare ultrasonographic features in patients with lymphocytic thyroiditis (LT) and papillary thyroid carcinoma (PTC) having suspicious thyroid nodule(s) in a background of heterogeneous parenchyma and to determine the clinical and radiological predictors of malignancy. METHODS: We reviewed the cases of 100 patients who underwent ultrasonography between April 2011 and October 2012, and showed suspicious thyroid nodule(s) in a background of heterogeneous parenchyma. Eight patients who did not undergo ultrasonography-guided fineneedle aspiration cytology (FNAC) and 34 cases of follow-up ultrasonography after initial FNAC were excluded. We compared the benign and malignant nodules in terms of their clinical and radiological factors. RESULTS: For the 58 nodules including 31 LTs (53.4%) and 27 PTCs (46.645 years is the most important predictor of malignancy in this condition.

Screening Ultrasound in Women with Negative Mammography: Outcome Analysis

PURPOSE: To show the results of an audit of screening breast ultrasound (US) in women with negative mammography in a single institution and to analyze US-detected cancers within a year and interval cancers. MATERIALS AND METHODS: During the year of 2006, 1974 women with negative mammography were screened with US in our screening center, and 1727 among them had pathologic results or any follow up breast examinations more than a year. We analyzed the distribution of Breast Imaging Reporting and Data System (BI-RADS) category and the performance outcome through follow up. RESULTS: Among 1727 women (age, 30-76 years, median 49.5 years), 1349 women (78.1%) showed dense breasts on mammography, 762 (44.1%) had previous breast US, and 25 women (1.4%) had a personal history of breast cancers. Test negatives were 94.2% (1.627/1727) [BI-RADS category 1 in 885 (51.2%), 2 in 742 (43.0%)]. The recall rate (=BI-RADS category 3, 4, 5) was 5.8%. Eight cancers were additionally detected with US (yield, 4.6 per 1000). The sensitivity, specificity, and positive predictive value (PPV1, PPV2) were 88.9%, 94.6%, 8.0%, and 28.0%, respectively. Eight of nine true positive cancers were stage I or in-situ cancers. One interval cancer was stage I cancer from BI-RADS category 2. CONCLUSION: Screening US detected 4.6 additional cancers among 1000. The recall rate was 5.8%, which is in lower bound of acceptable range of mammography (5-12%), according to American College of Radiology standard.

Ultrasonographic Classification of the Metastases to the Thyroid Gland / 대한갑상선학회지

BACKGROUND AND OBJECTIVES: To classify the metastases to the thyroid gland arising from non-thyroidal malignancies on ultrasound (US). MATERIALS AND METHODS: We enrolled 45 consecutive patients with metastases to the thyroid gland from 2005 to 2012. We classified metastases into 4 types; type I: diffuse non-mass forming lesion, type II: a solitary suspicious nodule, type III: multiple suspicious nodules, and type IV: nodule(s) with no suspicion. We subcategorized type I into two subtypes; type IA: diffusely infiltrative lesion, type IB: diffuse micronodulation. RESULTS: The most frequent primary malignancy of thyroid metastases was lung cancer. The patients with thyroid metastases were 26 (57.8%) in type I; type IA: 16 (35.6%), type IB: 10 (22.2%), 14 (31.1%) in type II, 3 (6.7%) in type III and 2 (4.4%) in type IV. Type I metastasis included 18 of 25 patients with lung cancer and all 3 patients with stomach cancer. Thirty patients (73.3%) having type IA, II or III revealed malignant findings on US, in contrast, 12 (26.7%) patients having type IB or IV revealed no suspicious findings. CONCLUSION: Type I (diffuse non-mass forming lesion) was the most common in thyroid metastases. A quarter of thyroid metastases revealed no suspicious findings on US. Thyroid metastases can be considered as a differential diagnosis, when diffuse non-mass forming lesions or nodules with no suspicion are revealed on thyroid US.