Non invasive assessment of malignancy in solitary non palpable thyroid nodules: A comparative and complimentary evaluation of grey scale ultrasound and color doppler parameters –Way towards a new scoring system?

Objectives: To assess the comparative as well as collective role of various grey scale (GS) ultrasonography (USG) and color doppler (CD) parameters in distinguishing benign from malignant thyroid nodules. To suggest a scoring system for predicting malignancy in thyroid nodules using this array of parameters. Methods: 140 patients with non palpable thyroid nodules were examined by five GS USG and three CD parameters. The results were compared with histopathological examination and evaluated statistically. Each GS and CD parameter was evaluated individually as well as collectively, comparatively. Total score was calculated by assigning each of these eight parameters a score of 0 to 2. Results: Scoring used in this study showed sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy of 87.5%, 90.6%, 70%, 96.7% and 80% respectively. These parameters were 85.4%, 86.2%, 60%, 96%, 80% for CD and 69.2%, 71.9%, 50%, 85.2% and 64% for GS. Two GS USG features showing p value < 0.05 were poorly defined margins and thick incomplete halo while on CD Resistivity index (RI) was found to be very highly significant (p < 0.0001) and Pulsatility index (PI) was highly significant (p < 0.001). Conclusion: Scoring system proposed in this study proved better than GS or CD individually for predicting malignancy in thyroid nodules. Amongst various GS and CD parameters RI showed highest statistical significance. Overall CD showed better accuracy, sensitivity, specificity than GS USG.