Category: Thyroid

Monitor: 9

9 - NEW ULTRASOUND CHARACTERISTIC TO PREDICT MALIGNANCY IN INDETERMINATE THYROID NODULES

Friday, Apr 26
12:30 PM – 1:00 PM

Objective :

Fine-needle aspiration (FNA) is the gold standard to evaluate thyroid nodules (TN). For indeterminate thyroid nodules (ITN), molecular mutation studies have become an effective tool for malignancy risk assessment, however, the cost is high. This study assessed ultrasound (US) features to predict malignancy in ITN.


Methods :

1402 sequential TN (greater than 1 cm) were biopsied from January 2015 - December 2016. US images of ITN (Bethesda III, IV, V) and Bethesda VI nodules were reviewed by experienced ultrasonographers and the data of those patients who had surgery (204) were included in the study. Demographic data, molecular studies, US characteristics and pathology results were compared between ITN and malignant nodules.


Results :

There were 153 (75%) ITN with pathological results: 91 (59.5%) benign (ITN-b) and 62 (40.5%) malignant (ITN-c). There were 51 (25%) Bethesda VI nodules and all were malignant. Among malignant nodules, there were 35.3% classic-PTC, 9.8% follicular variant-PTC, 4.9% NIFTP, 2.5% FTC or Hurthle cell carcinoma and 3% other types. ThyroSeq V.2 molecular tests were performed in 95.4% of ITN, of which 65.1% were positive. High risk mutations were lower in the ITN-b vs. ITN-c group (36.8% vs. 81.4%, P<0.01). As previously seen, US characteristics associated significantly (P<0.05) with malignancy include solid composition, taller than wide configuration, hypoechogenicity, abnormal margins, and cervical lymphadenopathy. We described a new characteristic: intranodular thick post-microcystic hyperechoic linear reflection (Thick-PMR) without reverberation. This finding was seen in 5.2% (8/153) of ITN and 64.7% (33/51) of Bethesda VI nodules. Based on the final surgical pathology, the feature was seen in none (0/91) of the benign nodules and 36.3% (41/113) of malignant nodules. Thick-PMR was significantly associated with malignancy in the ITN subgroup regardless of mutation status (P<0.01). We also found that thin post-microcystic reflection (Thin-PMR) were seen in both benign [48.4% (44/91)] and malignant [23% (26/113)] nodules, but were more common in the former (P<0.01).


Discussion :

Thick-PMR was significantly associated with malignant nodules with a high specificity in all FNA subgroups regardless of mutation status. Thin linear PMR was seen statistically more frequently in benign nodules, however, it can be seen in the malignant nodules.


Conclusion :

After future validation, thick-PMR may be a significant US feature similar to microcalcification, solid composition, hypoechogenicity and infiltrative margins useful in risk classification of TN for malignancy. 

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Nipawan Waisayanand

Fellow In training
1.Boston University School of Medicine. 2. Chiang Mai University., Massachusetts

Research Fellow of Boston University Medical Center, Department of Medicine, Section of Endocrinology, Diabetes & Nutrition, Boston, MA. and Staff of Faculty of Medicine, Chiang Mai University, Thailand.

Poorani Goundan

Doctor
Section of Endocrinology, Diabetes and Nutrition, Boston Medical Center, Massachusetts

Staff at Section of Endocrinology, Diabetes, and Nutrition, Boston Medical Center

Haixia Guan

Doctor
Section of Endocrinology, Diabetes and Nutrition Boston Medical Center
Boston, Massachusetts

Research fellow of Section of Endocrinology, Diabetes, and Nutrition. Boston Medical Center

Gianluca Toraldo

Doctor
Section of Endocrinology, Diabetes and Nutrition Boston Medical Center
Boston, Massachusetts

Research Fellow of Section of Endocrinology, Diabetes, and Nutrition. Boston Medical Center

Stephanie Lee

Professor
Boston Medical Center
Boston, Massachusetts

Professor of Medicine. Director, Thyroid Health Center. Section of Endocrinology, Diabetes, and Nutrition. Boston Medical Center