Comparison of Doppler Indices of Bilateral Superior Thyroid Arteries in Euthyroid and Hyperthyroid Patients

Abstract

BACKGROUND In this case-control study we aim to establish the relationship between the Doppler indices of the superior thyroid arteries and the functioning of the thyroid gland as seen by the thyroid function tests, ultrasonographic evaluation and colour Doppler of the thyroid gland. METHODS In this case-control study, ultrasonography of the thyroid gland with colour Doppler evaluation with Doppler indices of bilateral superior thyroid arteries and correlation with thyroid function test was done for patients presenting to the radio-diagnosis OPD. The total sample size was calculated using G*Power software with a level of significance alpha= 5% and power 1-beta= 80%; the effect size d= 0.75 with 95% confidence interval. The minimum sample size required in each group is 48 with a total sample size of 96. The data obtained was analysed with independent samples test. RESULTS Data was analysed using independent samples test with Levene's test for equality of variances and t-test for Equality of Means also done. Of all the patients (n=96) who came for ultrasound scan of thyroid gland, 70% (n=67) belonged to the 20-50 age group. 48 patients were included in the cases group, of this 79 % (n=38) were female and 21 % (n=10) were males. We found that the Doppler indices of STA in hyperthyroid patients were significantly higher than euthyroid subjects with p value <0.05. The controls (n=48) had a mean PSV-STA of 15.85 ± 1.89 cm/s, mean PI-STA of 0.9 ± 0.12 and mean RI-STA of 0.55 ± 0.07. The Doppler indices of hyperthyroid patients (n=48) was elevated with mean PSV-STA (cm/s) of 37.15 ± 7.6, the mean RI-STA of 0.72 ± 0.1 and mean PI-STA of 1.79 ± 0.23.