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Nonenhanced neck CT may detect diffuse thyroid disease
Nonenhanced CT images are effective for differentiating diffuse thyroid disease from normal thyroid, according to recent findings published in the International Journal of Endocrinology.
Myung Ho Rho, MD, of the Inje University College of Medicine in Korea, and Dong Wook Kim, MD, of the Sungkyunkwan University School of Medicine in Korea, evaluated 209 patients (170 women; aged 22-75 years) who received preoperative neck CT and subsequent thyroid surgery to determine the diagnostic accuracy of individual CT features, as well as cutoff criteria for detecting diffuse thyroid disease (DTD).
Papillary thyroid carcinoma was the most common histopathology of the main surgical thyroid lesion (n=186), followed by nodular hyperplasia (n=14), follicular adenoma (n=7) and follicular thyroid carcinoma (n=2). Thyroidectomy was the most common thyroid surgery (n=106), followed by hemithyroidectomy (n=87) and subtotal thyroidectomy (n=16). Normal thyroid was the most common histopathologic diagnosis (n=157), followed by non-Hashimoto’s lymphocytic thyroiditis (n=34), Hashimoto’s thyroiditis (n=17) and diffuse hyperplasia (n=1).
A significant difference between normal thyroid and DTD was found between the degree and pattern of parenchymal attenuation, glandular margin and pattern of parenchymal enhancement with frequencies of individual CT features. However, there was no difference found for glandular size.
Compared with other conditions, nonenhanced CT was most effective in diagnosing DTD using a cutoff value of <100 Hounsfield units in the thyroid parenchyma. However, no significant difference in cutoff value was found for the degree of parenchymal enhancement between normal thyroid and DTD.
Low attenuation, inhomogeneous attenuation, increased glandular size, lobulated margin and inhomogeneous enhancement were CT features suggestive of DTD. Isoattenuation, homogenous attenuation, anteroposterior diameter of 1 cm to 2 cm, smooth margin and homogenous enhancement were CT features that suggested normal thyroid.
Number of abnormal CT features were categorized as one or more (n=98), two or more (n=50), three or more (n=31), four or more (n=15) and five (n=5). DTD diagnosis accuracy was highest when the three or more classification was used.
“In conclusion, the study results showed that CT features suggestive of DTD included low attenuation, inhomogeneous attenuation, increased glandular size, lobulated margin and inhomogeneous enhancement and that CT diagnosis of DTD using the ‘3 or more’ CT classification was superior,” the researchers wrote. “In addition, most of [the] useful CT features for differentiating DTD from normal thyroid were detected in nonenhanced CT images.”
Disclosure: The researchers report no relevant financial disclosures.