Objective: The objective of this study was to evaluate the role of magnetic resonance diffusion-weighted imaging (DWI) in differentiating malignant from benign thyroid nodules.
Methods: The prospective study included 111 consecutive patients with solitary thyroid nodules (23 malignant and 88 benign nodules) who underwent DWI. The DWI signal and apparent diffusion coefficient (ADC) values of the nodules were determined and correlated with the histopathologic findings.
Results: The majority (65%) of malignant thyroid nodules showed slightly hyperintense, and the majority (69%) of benign nodules were hyperintense on DWI (P < 0.01). The ADC values were lower in the thyroid cancer than in the adenoma and nodular goiter (P < 0.05). When the b factor was 500 s/mm2, an ADC value of 1.704 × 10−3 mm2/s can be threshold differentiating malignant from benign nodules, with 92% sensitivity, 88% specificity, and 87% accuracy. The higher cell density and more severe desmoplastic response were the causes of the lower ADC value of thyroid cancer.
Conclusion: Diffusion-weighted imaging can be a promising noninvasive imaging to discriminate malignant from benign nodules.