Usefulness of Doppler ultrasound-obtained resistance index in thyroid nodules with ultrasonographic malignant characteristics

Introduction: Thyroid nodular disease is highly prevalent in the general population. Its diagnosis has increased with Doppler ultrasound, by means of which features suggestive of malignancy can be detected, such as resistance and pulsatility indices elevation. Objective: To assess the correlation of a high resistance index and histopathological findings in patients with ultra-sonographic suspicion of malignant thyroid nodules. Method: Prospective, cross-sectional, analytic, observational study of diagnostic tests carried out at Specialty Hospital 25, in Monterrey, Nuevo Leon. Patients with thyroid nodules of ultrasonographic malignant characteristics were included; the resistance index of the nodules was obtained and compared with histopathological findings. Results: Forty-eight patients with ultrasonographic diagnosis of malignant nodules were included. The correlation of elevated resistance indices with malignant thyroid nodule histopathologic diagnosis was significant (p = 0.001). Sensitivity was 73.3% and specificity 78.7%; positive predictive value was 61.1% and negative predictive value was 86.6%. Conclusion: The resistance index determination is increasingly being used, but its sensitivity and specificity are low, and it is not a reliable method, and other complementary methods are therefore still required.