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

Abstract

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.

Fig 1.

Category of no evidence of DTD in a 28-year-old woman. A and B, Transverse and longitudinal sonographic images of the thyroid show isoechogenicity, fine echotexture, an AP diameter from 1 to 2 cm, normal vascularity, a smooth margin, and the absence of scattered microcalcifications. Pathology results (not shown) showed a normal thyroid after thyroid surgery because of a follicular adenoma in the left lobe. C and D, A category of suggestive for DTD of the thyroid in a 33-year-old woman. Transverse and longitudinal sonographic images of the thyroid show mild hypoechogenicity, coarse echogenicity, mildly increased vascularity, and the presence of a microlobulated margin. Pathology results showed HT and a papillary thyroid carcinoma in the left lobe after thyroid surgery.

Fig 2.

Category of suggestive for DTD in a 39-year-old man (a false-positive). A and B, Transverse and longitudinal sonographic images of the thyroid show mild hypoechogenicity, coarse echogenicity, and the presence of a microlobulated margin, but the thyroid pathology results showed a papillary thyroid carcinoma in the left lobe and NTP after thyroid surgery.

Fig 3.

Category of no evidence of DTD in a 59-year-old woman (a false-negative). A and B, Transverse and longitudinal sonographic images of the thyroid show fine isoechogenicity, a normal range for the AP diameter, and the presence of a smooth margin. Pathology results showed a papillary thyroid carcinoma in the left lobe and chronic lymphocytic thyroiditis after thyroid surgery.