[Contribution of ultrasonography in the evaluation of subacute thyroiditis]

Ultrasonography is a useful tool in diagnosing and monitoring thyroid pathology. The aim of this study was to evaluate the value of thyroid ultrasonography in the follow-up of subacute thyroiditis (SAT). The study group included 48 subjects with clinical and biological diagnosis of subacute thyroiditis. All patients were evaluated by ultrasonography and followed-up for a mean period of 12 months. The evaluation protocol included biological data (TSH, T4, erythrocyte sedimentation rate--ESR) and ultrasonography, performed at 1, 2, 3, 6, and 12 months. Initially, all patients had an enlarged thyroid volume (median = 30.5 ml, range 23-90) and a low echogenicity, with an inhomogeneous aspect in 54.1% cases. After a mean period of 3 months thyroid volume had a significant reduction (median volume = 20.2 ml, range 7-36, p < 0.0001). Echogenicity was also significantly improved, with a decrement, on a semi-quantitative scale of 4 degrees (1 = normal, 4 = intense hypoechogenicity), from 3.25 to 2.48 (p < 0.0001). Almost half of the patients (45.8%) presented persistent (although slighter) hypoechoic/inhomogeneous pattern. Ultrasonographic abnormalities were not correlated with the intensity of the inflammatory syndrome and/or the thyroid status. Recurrence appeared in 10 (20.8%) patients. All patients presented a new thyroid enlargement (from a median = 16.1 ml to 31.5 ml, p = 0.056) and an extension of hypoechoic regions. The risk of recurrence could not be correlated with thyroid function, inflammatory syndrome or ultrasonographic aspect. There were not significant differences between the subgroups of patients with and without recurrence concerning the initial thyroid volume (p = 0.889), echogenicity (p = 0.735), TSH (p = 0.321) or ESR (p = 0.1332). Thyroid ultrasonography is useful not only for the initial diagnosis but also for the follow-up of patients with subacute thyroiditis. Remission and recurrence can be appreciated and monitored by the ultrasonographic pattern of the thyroid.