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The Diagnostic Value of Color Doppler Ultrasonography in Predicting Thyroid Nodules Malignancy.

BACKGROUND AND OBJECTIVE
Thyroid nodules are common medical and surgical problems. Although ultrasound has been proposed for evaluation of these nodules by many studies, but there is no consensus regarding its diagnostic accuracy and discriminatory cutoffs. We aimed to investigate the diagnostic value of Gray-scale and Color Doppler US in predicting thyroid nodules malignancy.


METHOD
This is an analytical cross-sectional study which was conducted on 63 patients with thyroid nodules. The patients with nodular goiter were evaluated by Color Doppler and Gray scale US, fine needle aspiration and surgery was performed in all the subjects. The sensitivity, specificity, positive predictive value, and negative predictive value of the finding in US and their cut offs were calculated. Data were analyzed by Chi-square and Mann Whitney U test in SPSS19. P-value less than 0.05 considered as statistically significant.


RESULTS
63 patients consisting of 55 (87.3%) female and 8 (12.7%) male patients with the age range of 20-70 years were enrolled in this study. 14% of nodules were reported as malignant in pathology. Singularity, hypo echogenicity, irregular margin, and micro calcification were significantly correlated with malignancy in nodules (p<0.05). Micro calcification and hypo echogenicity of the nodule were the most and the least discriminator of malignancy in nodules (sensitivity 77%, specificity 76% vs. 24%, PPV 41% vs., 14% and NPV 94% vs. 86%) respectively. Pulsatility Index and Mean Systolic Velocity were the most and the least predictor factors of thyroid malignancy (PPV 62% vs. 23% and NPV 100% vs. 91%, respectively). There was a significant association between Resistive Index and Pulsatility Index with malignancy with a cutoff of RI ≥ 0.715 (P=0.005) and PI ≥ 0.945 (P=0.007), respectively. The combination of calcification, RI ≥ 0.715 with PI ≥ 0.945 had a very diagnostic yield for diagnose of malignancy (PPV 66.6% and NPV 98.4%).


CONCLUSION
According to results, it seems that Grayscale US combined with Color Doppler are valuable modalities for evaluating thyroid nodules and can be used as a para-clinical method in order to assess the risk of malignancy in the patient with thyroid nodules.