CT features of thyroid nodules with isolated macrocalcifications detected by ultrasonography

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.

[Clinical Application of the 2021 Korean Thyroid Imaging Reporting and Data System (K-TIRADS)]

In patients with thyroid nodules, ultrasonography (US) has been established as a primary diagnostic imaging method and is essential for treatment decision. The Korean Thyroid Imaging Reporting and Data System (K-TIRADS) is a pattern-based, US malignancy risk stratification system that can easily diagnose nodules during real-time ultrasound examinations. The 2021 K-TIRADS clarified the US criteria for nodule classification and revised the size thresholds for nodule biopsy, thereby reducing unnecessary biopsies for benign nodules while maintaining the appropriate sensitivity to detect malignant tumors in patients without feature of high risk thyroid cancer. Thyroid radiology practice has an important clinical role in the diagnosis and non-surgical treatment of patients with thyroid nodules, and should be performed according to standard practice guidelines for proper and effective clinical care.

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.

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.

Korean Thyroid Imaging Reporting and Data System: Current Status, Challenges, and Future Perspectives

The Korean Thyroid Imaging Reporting and Data System (K-TIRADS) is an ultrasound-based risk stratification system for thyroid nodules that has been widely applied for the diagnosis and management of thyroid nodules since 2016. This review article provides an overview of the use of the K-TIRADS compared with other risk stratification systems. Moreover, this review describes the challenges in the clinical application of the K-TIRADS, as well as future development directions toward the personalized management of patients with thyroid nodules.

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.

Comparison of the diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System for thyroid malignancy with three international guidelines

Purpose

This study compared the diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System (K-TIRADS) for thyroid malignancy with three international guidelines.

Methods

From June to September 2015, 5,708 thyroid nodules (≥1.0 cm) in 5,081 consecutive patients who underwent thyroid ultrasound (US) at 26 institutions were evaluated. The US features of the thyroid nodules were retrospectively reviewed and classified according to all four guidelines. In the modified K-TIRADS, the biopsy size threshold was changed to 2.0 cm for K-TIRADS 3 and 1.0 or 1.5 cm for K-TIRADS 4 (K-TIRADS_1.0cm and K-TIRADS_1.5cm, respectively). We compared the diagnostic performance and unnecessary fine-needle aspiration biopsy (FNAB) rates for thyroid malignancy between the modified K-TIRADS and three international guidelines.

Results

Of the 5,708 thyroid nodules, 4,597 (80.5%) were benign and 1,111 (19.5%) were malignant. The overall sensitivity was highest for the modified K-TIRADS_1.0cm (91.0%), followed by the European (EU)-TIRADS (84.6%), American Association of Clinical Endocrinologists/American College of Endocrinology/Associazione Medici Endocrinologi (AACE/ACE/AME) (80.5%), American College of Radiology (ACR)-TIRADS (76.1%), and modified K-TIRADS_1.5cm (76.1%). For large nodules (>2.0 cm), the sensitivity increased to 98.0% in both the modified K-TIRADS_1.0cm and K-TIRADS_1.5cm. For small nodules (≤2.0 cm), the unnecessary FNAB rate was lowest with the modified K-TIRADS_1.5cm (17.6%), followed by the ACR-TIRADS (18.6%), AACE/ACE/AME (19.3%), EU-TIRADS (28.1%), and modified K-TIRADS_1.0cm (31.2%).

Conclusion

The modified K-TIRADS_1.5cm can reduce the unnecessary FNAB rate for small nodules (1.0-2.0 cm), while maintaining high sensitivity for detecting malignancies >2.0 cm.

Diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System for thyroid malignancy according to nodule size: a comparison with five society guidelines

Purpose

The aim of this study was to evaluate the diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System (K-TIRADS) compared with five society risk stratification systems (RSSs) according to nodule size.

Methods

In total, 3,826 consecutive thyroid nodules (≥1 cm) with final diagnoses in 3,088 patients were classified according to five RSSs. The K-TIRADS was modified by raising the biopsy size threshold for low-suspicion nodules and subcategorizing intermediate-suspicion nodules. We assessed the performance of the RSSs as triage tests and their diagnostic accuracy according to nodule size (with a threshold of 2 cm).

Results

Of all nodules, 3,277 (85.7%) were benign and 549 (14.3%) were malignant. In small thyroid nodules (≤2 cm), the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) had the highest reduction rate of unnecessary biopsies (76.3%) and the lowest sensitivity (76.1%). The modified K-TIRADS had the second highest reduction rate of unnecessary biopsies (67.6%) and sensitivity (86.6%). The modified K-TIRADS and ACR TI-RADS had the highest diagnostic odds ratios (P=0.165) and the highest areas under the curve (P=0.315). In large nodules (>2 cm), the sensitivity of the ACR TI-RADS for malignancy was significantly lower (88.8%) than the sensitivities of the modified K-TIRADS and other RSSs, which were very high (98.7%-99.3%) (P<0.001).

Conclusion

The modified K-TIRADS allows a large proportion of unnecessary biopsies to be avoided, while maintaining high sensitivity and diagnostic accuracy for small malignant tumors and very high sensitivity for large malignant tumors.