Jenny Hoang

BACKGROUND: In many risk-stratification systems, the decision to biopsy thyroid nodules is determined by their sonographic features and size. Nevertheless, even low-suspicion nodules are often biopsied at small size thresholds because it is assumed that larger malignant nodules are associated with poorer outcomes. The aim of this study was to quantify the effect of thyroid cancer tumor size on survival and risk of T4 stage, nodal disease, and distant metastases. METHODS: The Surveillance, Epidemiology, and End Results 18 database was queried to obtain tumor size, staging information, and survival data for cases of differentiated thyroid cancer (DTC) and non-DTC reported between 2004 and 2014. Observed probabilities of tumor extent at diagnosis, including regional nodal disease and distant metastases, as a function of size and tumor histology were estimated for thyroid cancers measuring between 1 and 150 mm. A multivariate Cox regression model was used to describe all-cause mortality as a function of patient and tumor characteristics, and the functional dependence of mortality on size was computed. RESULTS: A total of 112,128 patients were analyzed, with 67% having thyroid cancers ≥1 cm, and 29% ≥ 2.5 cm. For DTC tumors <4 cm, the risk of local invasion, nodal metastases, or distant metastases was low, and there was no size threshold associated with a sharp rise in adverse outcomes. For DTC tumors <4 cm, the probability of distant metastases was <3%. Older age, male sex, non-DTC histology, T4 stage, and regional and distant metastatic disease increased the all-cause mortality rate. Tumor size did not increase the mortality rate above baseline until tumors were >2.5 cm. CONCLUSION: Increasing tumor size does not affect survival until a threshold of 2.5 cm. Since the dimension of nodules on ultrasound has been shown to be larger than their size at gross pathology, these findings suggest that recommended size thresholds to biopsy low-suspicion thyroid nodules can be increased.

© 2017, Springer Science+Business Media New York. Purpose of Review: Radiologic localization of parathyroid lesions is essential for the surgical treatment of primary hyperparathyroidism. In recent years, multiphase parathyroid 4D-CT has evolved from an adjunct imaging technique to a first-line choice for planning parathyroidectomy at some institutions. Here, we review the background, technique, and interpretation of parathyroid 4D-CT. Recent Findings: Compared with the traditional modalities of scintigraphy and ultrasound, CT provides superior sensitivity for localizing parathyroid lesions, and is particularly valuable in the setting of planning remedial surgery and when patients have multi-gland disease (double adenomas or four-gland hyperplasia). A three-phase CT protocol optimizes lesion detection and characterization. A systematic approach to image interpretation and reporting, incorporating the Duke 4D-CT scoring system, enables radiologists to convey relevant information and facilitate successful surgery. Summary: We recommend using a three-phase CT protocol and provide an updated six-step approach to parathyroid CT interpretation and reporting.

Ultrasound is the most commonly used imaging technique for the evaluation of thyroid nodules. Sonographic findings are often not specific, and definitive diagnosis is usually made through fine-needle aspiration biopsy or even surgery. In reviewing the literature, terms used to describe nodules are often poorly defined and inconsistently applied. Several authors have recently described a standardized risk stratification system called the Thyroid Imaging, Reporting and Data System (TIRADS), modeled on the BI-RADS system for breast imaging. However, most of these TIRADS classifications have come from individual institutions, and none has been widely adopted in the United States. Under the auspices of the ACR, a committee was organized to develop TIRADS. The eventual goal is to provide practitioners with evidence-based recommendations for the management of thyroid nodules on the basis of a set of well-defined sonographic features or terms that can be applied to every lesion. Terms were chosen on the basis of demonstration of consistency with regard to performance in the diagnosis of thyroid cancer or, conversely, classifying a nodule as benign and avoiding follow-up. The initial portion of this project was aimed at standardizing the diagnostic approach to thyroid nodules with regard to terminology through the development of a lexicon. This white paper describes the consensus process and the resultant lexicon.

The incidental thyroid nodule (ITN) is one of the most common incidental findings on imaging studies that include the neck. An ITN is defined as a nodule not previously detected or suspected clinically, but identified by an imaging study. The workup of ITNs has led to increased costs from additional procedures, and in some cases, to increased risk to the patient because physicians are naturally concerned about the risk of malignancy and a delayed cancer diagnosis. However, the majority of ITNs are benign, and small, incidental thyroid malignancies typically have indolent behavior. The ACR formed the Incidental Thyroid Findings Committee to derive a practical approach to managing ITNs on CT, MRI, nuclear medicine, and ultrasound studies. This white paper describes consensus recommendations representing this committee's review of the literature and their practice experience.