The role of color flow Doppler sonography study in differential diagnosis of thyrotoxicosis

Abstract

Background: Thyrotoxicosis is a metabolic state of excessive thyroid hormones which include tetraiodothyronine (FT4) and/or triiodothyronine (FT3). The most common causes of thyrotoxicosis are either autoantibody-mediated hyperfunction of thyroid gland (Graves’ disease) or inflammation-induced destructive thyroiditis (subacute thyroiditis and postpartum thyroiditis). The correct diagnosis of thyrotoxicosis is important as management differs according to etiology. The radioactive iodine uptake test and technetium pertechnetate thyroid scan are the gold standard for diagnosis of thyrotoxicosis. However, these tests are limited by their availability and high cost. Therefore, it is important to look for other parameters which can help in the diagnosis of hyperthyroidism. The non-invasive thyroid color flow Doppler sonography (CFDS) is an easily available, highly informative, safe, and comparatively low-cost investigation which can be used as an alternative. Aims and Objectives: The aim of the study was to assess the role of CFDS in the differential diagnosis of thyrotoxicosis. Materials and Methods: A total number of 120 newly diagnosed thyrotoxic patients were enrolled. On the basis of clinical, laboratory evaluation, and thyroid scan, patients were diagnosed with either Graves’ disease or thyroiditis. All the patients underwent CFDS in the radiology department. Results: Ninety patients of Graves’ disease and thirty patients of thyroiditis were enrolled in our study. The mean peak systolic velocity (PSV) of inferior thyroid artery (ITA) from both lobes of thyroid gland were used as markers of thyroid vascularity. The difference in mean PSV-ITA in Graves’ and thyroiditis patients was statistically significant (P < 0.001). Using receiver operating characteristic analysis for diagnostic accuracy of PSV, we demonstrated that the cutoff 50 cm/s had 98.9% sensitivity and 96.7% specificity in differentiating Graves’ disease from thyroiditis with positive predictive value and negative predictive value being 99% and 96%, respectively. Conclusion: A non-invasive CFDS is an inexpensive and easily available procedure which provides the functional status of the thyroid gland. The PSV of ITA can help to differentiate the etiologies of thyrotoxicosis and can be considered as an alternative to nuclear scanning where such modality is not present or contraindicated.