ROLE OF DIFFUSION WEIGHTED MRI IN DIFFERENTIATING BENIGN FROM MALIGNANT THYROID NODULES

Abstract

Introduction: Thyroid nodules are most frequently noticed in clinical practice. Although the majority of these nodules are benign, up to 15% of them are malignant. Advanced diagnostic imaging tools, which are non-invasive such as DWI techniques, have been accurate in discriminating the growth of thyroid nodules. The aim of the present study was to assess the role of DWI and ADC in discriminating the growth (malignant and benign) and to determine other imaging features that can help in identifying neoplastic etiology. Material and methods: This study was a cross-sectional study involving subjects with thyroid swelling or nodule on clinical examination and on ultrasonography. ADC values were computed for the different b-values. Histopathology results were obtained for all the patients. ADC values of benign and malignant thyroid lesions were compared with the histopathology results. P-value < 0.05 was considered as statistically significant. Results: The sample size was 43 subjects, and female subjects were in the majority. The difference in the proportion of HPE findings between ADC values of the thyroid nodules was statistically significant (P-value <0.001). The ADC cut off value of 1.15 x 10-3 mm2/s resulted in sensitivity of 87.50% in predicting final HPE diagnosis. Specificity was 94.29%, and the total diagnostic accuracy was 93.02%. The ADC value of thyroid nodules obtained had excellent predictive validity in predicting malignancy, as indicated by the area under the curve of 0.925 (P-value <0.001). Conclusions: Using b factor of 800, ADC cut off value of 1.15 x 10-3 mm2/s resulted in accuracy, sensitivity and specificity of 93.02 %, 87.50 %, and 94.29 %, respectively for discriminating between malignant and benign thyroid nodules.