Thyroid Ultrasound Features and Risk of Carcinoma: A Systematic Review and Meta-Analysis of Observational Studies

Abstract

Background: Thyroid nodules are a common finding in the general population, and their detection is increasing with the widespread use of ultrasound (US). Thyroid cancer is found in 5–15% of cases depending on sex, age, and exposure to other risk factors. Some US parameters have been associated with increased risk of malignancy. However, no characteristic seems sufficiently reliable in isolation to diagnose malignancy. The objective of this meta-analysis was to evaluate the diagnostic performance of US features for thyroid malignancy in patients with unselected thyroid nodules and nodules with indeterminate fine-needle aspiration (FNA) cytology.Methods: Electronic databases were reviewed for studies published prior to July 2012 that evaluated US features of thyroid nodules and reported postoperative histopathologic diagnosis. A manual search of references of review and key articles, and previous meta-analyses was also performed. A separate meta-analysis was performed including only nodules with indeterminate cytology. Analyzed features were solid structure, hypoechogenicity, irregular margins, absence of halo, microcalcifications, central vascularization, solitary nodule, heterogeneity, taller than wide shape, and absence of elasticity.Results: Fifty-two observational studies (12,786 nodules) were included. Nine studies included nodules with indeterminate cytology as a separate category, comprising 1851 nodules. In unselected nodules, all US features were significantly associated with malignancy with an odds ratio varying from 1.78 to 35.7, and microcalcifications, irregular margins, and a taller than wide shape had high specificities (Sp; 87.8%, 83.1%, 96.6%) and positive likelihood ratios (LHR; 3.26, 2.99, 8.07). Absence of elasticity was the single feature with the best diagnostic performance (sensitivity 87.9%, Sp 86.2%, and positive LHR 6.39). The presence of central vascularization was the most specific US feature in nodules with indeterminate cytology (Sp 96% and positive LHR 2.13).Conclusions: US features in isolation do not provide reliable information to select nodules that should have a FNA performed. A combination of US characteristics with higher likelihood ratios and consequently with higher post-test probabilities of malignancy—microcalcifications, or a taller than wide shape, or irregular margins, or absence of elasticity—will probably identify nodules with an increased risk for malignancy. Further studies are required to standardize elastography techniques and evaluate outcomes, especially in nodules with an indeterminate cytology.

Likelihood of malignancy in thyroid nodules according to a proposed Thyroid Imaging Reporting and Data System (TI-RADS) classification merging suspicious and benign ultrasound features

“…Previously, the detection of any degree of internal blood flow was positively related to an increased likelihood of malignancy (17,28,33). However, in our study, this finding was not a useful predictor of malignancy.…”

“…All nodules were evaluated and classified according to the presence of 20 predefined ultrasound features, mostly retrieved from a literature review (4,5,(7)(8)(9)(10)(11)21,(25)(26)(27)(28)(29)(30)(31)(32)(33)(34) and detailed in Table 1. These features were included in a multiple logistic regression analysis to determine whether they were (or not) independently associated with the likelihood of malignancy (4,5,(8)(9)(10)(11)(24)(25)(26)(28)(29)(30)34).…”

Thyroid Imaging Reporting and Data System (TIRADS) in Stratifying Risk of Thyroid Malignancy at The Medical City

“…But the sensitivity of ultrasound features predictive of malignancy only ranged from 26.7 to 63% and the author concluded that ultrasound features in isolation do not provide reliable guide as when to do FNAB. 19 Fine needle aspiration biopsy is the preferred initial diagnostic method for the evaluation of thyroid nodules. Most of the thyroid nodules biopsied are benign and only approximately 3-7% of thyroid FNAB are malignant.…”

Analiza znaczenia klinicznego niejednoznacznych wyników biopsji tarczycy ze szczególnym uwzględnieniem kategorii ZPBN na podstawie 5 lat stosowania nowej klasyfikacji rozpoznań cytologicznych

“…This could be a consequence of the diversity of the examined populations, different frequencies of particular types of thyroid cancers in the examined groups, different size of these groups, and various proportions of benign and malignant nodules. The large meta-analysis by Remonti et al [49] was an attempt to summarise analyses published so far. The authors drew the conclusion that in the subgroup of nodules with indeterminate cytology any of the US features was sufficient to determinate the risk of malignancy with an acceptable SEN [49].…”

“…The large meta-analysis by Remonti et al [49] was an attempt to summarise analyses published so far. The authors drew the conclusion that in the subgroup of nodules with indeterminate cytology any of the US features was sufficient to determinate the risk of malignancy with an acceptable SEN [49]. It seems that such a view is shared by the majority of clinicians because, as indicated by our data and other published reports, they tended to refer for surgical treatment younger patients or those with larger nodules, but not those with suspicious US image [23,50].…”