Sonographic differentiation of asymptomatic diffuse thyroid disease from normal thyroid: a prospective study.

BACKGROUND AND PURPOSE There is no useful guide or study related to the differentiation of asymptomatic diffuse thyroid disease from normal thyroid by using thyroid US. This study was prospectively designed to evaluate the efficacy of the use of real-time thyroid sonography as performed by an experienced radiologist for the identification of asymptomatic DTD. MATERIALS AND METHODS From January 2008 to December 2008, 2267 patients underwent thyroid sonography in our hospital by 1 radiologist. Each patient's thyroid was prospectively classified as being in 1 of 4 of the following diagnostic categories on the basis of the sonographic features as determined with the use of real-time sonography: suggestive for DTD, suspicious for DTD, indeterminate, and no evidence of DTD. We calculated the diagnostic efficacy of the sonographic classifications compared with the pathology results. RESULTS Sonographic classifications for DTD in 340 patients who underwent thyroid surgery because of thyroid malignancy or other causes included the following: suggestive for DTD (n = 32), suspicious for DTD (n = 39), indeterminate (n = 18), and no evidence of DTD (n = 251). On the pathology, HT (n = 33), chronic lymphocytic thyroiditis (n = 27), diffuse hyperplasia (n = 2), and NTP (n = 278) were identified. There were true-positive cases (n = 50), true-negative cases (n = 244), false-positive cases (n = 21), and false-negative cases (n = 7). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for a diagnosis of asymptomatic DTD were 87.7%, 92.1%, 70.4%, 97.2%and 91.3%, respectively. CONCLUSIONS The present sonographic classification based on real-time sonography of the thyroid is a useful tool for differentiating asymptomatic DTD from normal thyroid.