Can Vascularity at Power Doppler US Help Predict Thyroid Malignancy?

To retrospectively evaluate the diagnostic performance of power Doppler ultrasonography (US) in depicting vascularity and to determine whether the combination of vascularity and suspicious gray-scale US features is more useful in predicting thyroid malignancy than are gray-scale features alone. This was an institutional review board-approved retrospective study, with waiver of informed consent. A total of 1083 thyroid nodules in 1024 patients (median age, 51 years; range, 16-83 years), consisting of 886 women (median age, 50 years; range, 16-83 years) and 138 men (median age, 53 years; range, 19-74 years), were included. Nodules with marked hypoechogenicity, noncircumscribed margins, microcalcifications, and taller-than-wide shape were classified as suspicious according to gray-scale US criteria. Vascularity was classified as none, peripheral, and intranodular. The diagnostic performance of gray-scale and power Doppler US features was compared and classified as follows: criterion 1, any single suspicious gray-scale US feature; criterion 2, addition of any vascularity as one of the suspicious features to criterion 1; criterion 3, addition of peripheral vascularity to criterion 1; criterion 4, addition of intranodular vascularity to criterion 1; criterion 5, addition of no vascularity to criterion 1; criterion 6, American Association of Clinical Endocrinologists and Associazione Medici Endocrinology guidelines--all hypoechoic nodules with at least one of the following US features: irregular margins, intranodular vascular spots, taller-than-wide shape, or microcalcifications. Of 1083 nodules, 814 were benign and 269 were malignant. Intranodular vascularity was frequently seen in benign nodules and no vascularity was more frequent in malignant nodules (P < .0001, respectively). The area under the receiver operating characteristic curve (A(z)) of criterion 1 was superior (A(z) = 0.851) to that of criteria 2 (A(z) = 0.634), 3 (A(z) = 0.752), 4 (A(z) = 0.733), 5 (A(z) = 0.718), and 6 (A(z) = 0.806) (P < .0001). Vascularity itself or a combination of vascularity and gray-scale US features was not as useful as the use of suspicious gray-scale US features alone for predicting thyroid malignancy.