Color doppler ultrasonography of inferior thyroid artery and its relation with thyroid functional state

Background: Not enough information has been gathered regarding the parameters of color Doppler ultrasonography (CDU) for evaluating diffuse thyroid disorders in Taiwan. The aims of this study were to compare the CDU parameters between the right and left inferior thyroid arteries (ITAs), and to investigate which CDU parameters can differentiate between euthyroid and hyperthyroid glands. Patients and methods: We retrospectively reviewed data from patients who had undergone CDU to image thyroid disorders from December 2003 to April 2004 in order to analyze the CDU parameters that can be used to evaluate bilateral ITA. The mean age of the patients was 40.8 ± 16.6 years (range, 10-72 years). The female to male distribution was 2.2:1 (43 females and 20 males). The ITA of patients with normal thyroid, simple goiter and autoimmune thyroid disease were scanned with CDU. The parameters evaluated included pulsatility index (PI), resistive index (RI), peak systolic velocity (PSV), blood volume flow (VF) and diameter (Diam) of ITA. We then evaluated the relationships among these parameters between the right and the left ITAs and differences in parameters between patients with euthyroidism and hyperthyroidism. Significant parameters were analyzed by the t test and simple linear regression. Results: There was good Pearson's correlation among all parameters (PI, RI, PSV, VF and Diam) (p< 0.001) between the right and left ITAs in all 63 patients. No significant differences were noted between the right and left ITAs (p> 0.05). These same results were seen in patients with euthyroidism (30 patients) and hyperthyroidism (27 patients), except that Diam of ITA had poor correlation between both sides in the hyperthyroid group. The CDU parameters of ITA were higher in patients with hyperthyroidism than in those with euthyroidism. Conclusion: There were no significant differences in CDU parameters between the right and left ITAs. However, all parameters had higher values in patients with hyperthyroidism than in those with normal thyroid function. Therefore, we conclude that unilateral ITA CDU can be used to evaluate diffuse thyroid disorder. A large-scale study is needed to investigate which CDU parameters can be used to differentiate between euthyroid and hyperthyroid status in clinical practice.