Objective: The purpose of this article is to present, through systematic review of recent literature, a comparative effectiveness analysis of ultrasound elastography versus B-mode ultrasound features for differentiating thyroid nodules.
Materials and methods: We conducted an extensive literature search of PubMed and other medical and general purpose databases from January 1966 through March 2012. Eligible studies were published in English, reported diagnostic performance of elastography (using elasticity score or strain ratio) with or without B-mode ultrasound in differentiation of thyroid nodules, and used histology or cytology as the reference standard. Summary diagnostic performance measures were assessed for each of the elasticity measuring methods and ultrasound features by means of a bivariate random effects model.
Results: Twenty-four studies provided relevant information on more than 2624 patients and 3531 thyroid nodules (927 malignant and 2604 benign). Six ultrasound features (echogenicity, calcifications, margins, halo sign, shape, and color Doppler flow pattern) were compared with elasticity score and strain ratio. The respective sensitivities and specificities were as follows: elasticity score, 82% and 82%; strain ratio, 89% and 82%; hypoechogenicity, 78% and 55%; microcalcifications, 50% and 80%; irregular margins, 66% and 81%; absent halo sign, 56% and 57%; nodule vertical development, 46% and 77%; and intranodular vascularization, 40% and 61%.
Conclusion: Evaluation of thyroid nodules with ultrasound elastography appears to be both more sensitive and specific than each of the ultrasound features. The former is a safe and effective technique that warrants further rigorous investigation or use in the clinical diagnosis of thyroid nodules.