Abstract：Objective: To assess the efficacy of using different b values diffusion weighted imaging(DWI) of MRI in the evaluation of thyroid nodule malignancy. Methods: Seventy-seven patients with single or multiple thyroid nodules（totally 120 nodules）were included in this study. The thyroid nodules' ADC (apparent diffusion coefficient) with different b values were assessed by Independent-Sample t test. Receiver operating characteristic (ROC) curves were drawn. Results: Malignant thyroid nodules showed significantly lower ADC than benign ones. The b-300 s/mm 2 ADC values of benign and malignant thyroid nodules was（2.113±0.639）×10-3 and（1.784±0.544）×10-3 mm 2/s respectively; the b-500 s/mm2 ADC values was（1.856±0.547）×10 -3 and（1.488±0.412）×10 -3 mm 2/s respectively; the b-800 s/mm2 ADC values of benign and malignant nodules was（1.484±0.556）×10 -3 and （1.264±0.356）×10-3 mm 2/s respectively. Sensitivity was 76.00%,84.00% and 73.97%，respectively; specificity was 51.11%, 46.67% and 60.00%，respectively; positive predictive value was 68.0%, 67.9% and 70.2%，respectively; negative predictive value was 63.5%, 70.2% and 63.8%, respectively. Conclusion: Different b values ADC may help differentiating benign thyroid nodules from malignant ones, but it is not sufficient to differentiate thyroid nodules malignancy by using one of any b value ADC alone.
［Key words］thyroid nodule; thyroid carcinoma; magnetic resonance imaging; diffusion weighted imaging
2017, Vol. 27 
