Date Published: November 15, 2018
Publisher: Public Library of Science
Author(s): Hye Jin Baek, Dong Wook Kim, Yoo Jin Lee, Hye Jung Choo, Hye Shin Ahn, Hyun Kyung Lim, Ji Hwa Ryu, Rubens Chojniak.
This study aimed to assess the diagnostic performance of computed tomography (CT) for differentiating diffuse thyroid disease (DTD) from normal thyroid parenchyma (NTP) using multicenter data. Between January 2016 and June 2016, 229 patients underwent preoperative neck CT and subsequent thyroid surgery at five participating institutions. The neck CT images of each patient were retrospectively reviewed and classified into the following four categories: no DTD, indeterminate, suspicious for DTD, and DTD. The results of the CT image evaluations were compared with the histopathological results to determine the diagnostic accuracy of CT at each institution. According to the histopathological results, there were NTP (n = 151), Hashimoto thyroiditis (n = 24), non-Hashimoto lymphocytic thyroiditis (n = 47), and diffuse hyperplasia (n = 7). The CT categories of the 229 patients were “no DTD” in 89 patients, “indeterminate” in 40 patients, “suspicious for DTD” in 42 patients, and “DTD” in 58 patients. The presence of two or more CT features of DTD, which was classified as “suspicious for DTD” by all radiologists, had the largest area under the receiver-operating characteristic curve (Az = 0.820; 95% confidence interval: 0.764, 0.868), with sensitivity of 85.9% and specificity of 78.2%. However, no statistical significance between readers’ experience and their diagnostic accuracy was found. In conclusion, evaluations of CT images are helpful for differentiating DTD from NTP.
Diffuse thyroid disease (DTD), a major cause of thyroid dysfunction, is classified into autoimmune and non-autoimmune diseases. Two common thyroid autoimmune diseases are Graves’ disease, which is usually associated with hyperthyroidism, and Hashimoto thyroiditis, which is typically associated with hypothyroidism . Previous studies have suggested an association between DTD and thyroid malignancy, although the clinical significance of this relationship is still under debate [2–4]. Therefore, regular monitoring of patients with DTD is performed at many institutions. Cases of symptomatic DTD are easily diagnosed by clinical and serological examinations, such as thyroid autoantibody or thyroid function tests; however, reliable diagnostic tools for detecting asymptomatic or subclinical DTD have not been established [5–8].
In the current study, we found that the CT diagnosis was helpful for detecting incidental DTD. The presence of two or more abnormal CT features (i.e., “suspicious for DTD” or “DTD” category) had the highest Az value, indicating that this classification had the highest diagnostic accuracy, which is consistent with the published literature . The diagnostic values identified here were similar to those reported in previous studies that diagnosed DTD using ultrasonography or CT, but the negative predictive value of the current study was higher than the previously reported values [5–8]. However, the recent study showed that the presence of three or more abnormal CT features had the greatest diagnostic accuracy but lower sensitivity . Regardless, to our knowledge, this is the first multicenter study to demonstrate the feasibility of using CT to evaluate and diagnose DTD by revealing a correlation between the CT findings and the histopathological results.
Our study demonstrates that the CT diagnosis is helpful for differentiating DTD from NTP regardless of the experience of the investigators. In particular, when two or more abnormal CT features are observed, the possibility of DTD should be considered.