Quantitative analyses of the correlation between dynamic contrast-enhanced MRI and intravoxel incoherent motion DWI in thyroid nodules

This study investigated the correlation between dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and intravoxel incoherent motion diffusion-weighted imaging (IVIM DWI) to differentiate thyroid nodules. Quantitative DCE-MRI parameters, including the transfer constant (K-trans), rate constant (K-ep) and volume fraction of the extracellular extravascular space (V-e), were calculated. The diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) were derived from biexponential fitting of IVIM DWI. A total of 38 nodules, including 22 malignant and 16 benign nodules, were analyzed. The K-trans, K-ep and V-e for benign lesions were 1.32 +/- 0.76 min(-1), 6.44 +/- 1.44 min(-1), and 2.02 +/- 0.89 min(-1), respectively, and for malignant lesions, the values were 0.84 +/- 0.30 min(-1), 5.43 +/- 1.38 min(-1), and 1.71 +/- 0.83 min(-1), respectively (P = 0.027, 0.036, and 0.257, respectively). The D, f, and D* for benign lesions were 1.51 +/- 0.52 mm(2)/s, 26.63 +/- 8.75%, and 15.84 +/- 8.71 mm(2)/s, respectively, and for malignant lesions, the values were 0.68 +/- 0.17 mm(2)/s, 31.63 +/- 10.72%, and 11.10 +/- 4.21 mm(2)/s, respectively (P [ 0.0001, 0.135, 0.058], respectively). No significant correlations were found between IVIM DWI and DCE-MRI quantitative parameters (all P 0.05). In benign nodules, a moderate inverse correlation was found between D and K-ep (r =-0.54, P = 0.031). IVIM DWI shows no significant correlation with perfusion parameters derived from DCE-MRI; however, IVIM DWI combined with quantitative DCE-MRI may be a useful imaging tool for the assessment of thyroid nodules in clinical studies.