The Diagnostic Utility of Color Doppler Ultrasonography, Tc-99m Pertechnetate Uptake, and TSH-Receptor Antibody for Differential Diagnosis of Graves' Disease and Silent Thyroiditis: A Comparative Study.

Objective: The differential diagnosis of Graves disease (GD) and silent thyroiditis (ST) is important for the selection of appropriate treatment. To date, no study has compared the diagnostic utility of color Doppler ultrasonography (CDUSG), Tc-99m (technetium-99m) pertechnetate uptake, and thyroid-stimulating hormone (TSH)-receptor antibody (TRAb) for the differential diagnosis of these two conditions. In the present study, we compared the diagnostic utility of inferior thyroid artery (ITA) peak systolic and end diastolic velocities (PSV and EDV) measured by CDUSG, Tc-99m pertechnetate uptake, and TRAb for differential diagnosis of GD and ST.

Methods: A total of 150 subjects with GD, 79 with ST, and 71 healthy euthyroid controls were included in the study. Diagnoses of GD and ST were made according to patient signs and symptoms, physical examination findings, the results of TRAb and Tc-99m pertechnetate uptake, and follow-up findings. All subjects underwent CDUSG for the quantitative measurement of ITA blood-flow velocities.

Results: The mean ITA-PSV and EDV in patients with GD were significantly higher than in ST patients. In receiver operating characteristic analysis, the sensitivity/specificity of the 30 and 13.2 cm/s cutoff values of the mean ITA-PSV and EDV for discrimination of GD from ST were 95.3/94.9% and 89.3/88.6%, respectively. The sensitivity/specificity of the 1.0 international unit (IU)/L and 3% cutoff values of the TRAb and Tc-99m pertechnetate uptake analyses were 93.0/91.0% and 90.7/89.9%, respectively.

Conclusion: The measurement of ITA-PSV by CDUSG is a useful diagnostic tool and is a complementary method to the TRAb and Tc-99m pertechnetate uptake methods for differential diagnosis of GD and ST.