Preliminary study of diffusion kurtosis imaging in thyroid nodules and its histopathologic correlation.

OBJECTIVES: To evaluate the utility of diffusion kurtosis imaging (DKI) of patients with thyroid nodules and to assess the probable correlation with histopathological factors. METHODS: The study included 58 consecutive patients with thyroid nodules who underwent magnetic resonance imaging (MRI) examination, including DKI and diffusion-weighted imaging (DWI). Histopathological analysis of paraffin sections included cell density and immunohistochemical analysis of Ki-67 and vascular endothelial growth factor (VEGF). Statistical analyses were performed using Student's t-test, receiver operating characteristic (ROC) curves and Spearman's correlation. RESULTS: The diffusion parameters, cell density and immunohistochemistry analysis between malignant and benign lesions showed significant differences. The largest area under the ROC curve was acquired for the D value (AUC = 0.797). The highest sensitivity was shown with the use of K (threshold = 0.832, sensitivity = 0.917). The Ki-67 expression generally stayed low. A moderate correlation was found between ADC, D and cell density (r = -0.536, P = 0.000; r = -0.570, P = 0.000) and ADC, D and VEGF expression (r = -0.451, P = 0.000; r = -0.522, P = 0.000). CONCLUSION: The DKI-derived parameters D and K demonstrated an advantage compared to conventional DWI for thyroid lesion diagnosis. While the histopathological study indicated that the D value correlated better with extracellular change than the ADC value, the K value probably changed relative to the intracellular structure. KEY POINTS: • DWI and DKI parameters can identify PTC from benign thyroid nodules. • Correlations were found between diffusion parameters and histopathological analysis. • DKI obtains better diagnostic accuracy than conventional DWI.