Diffusion kurtosis imaging and dynamic contrast-enhanced MRI for the differentiation of parotid gland tumors

OBJECTIVE: To assess the usefulness of combined diffusion kurtosis imaging (DKI) and dynamic contrast-enhanced MRI (DCE-MRI) in the differentiation of parotid gland tumors. METHODS: Seventy patients with 80 parotid gland tumors who underwent DKI and DCE-MRI were retrospectively enrolled and divided into four groups: pleomorphic adenomas (PAs), Warthin tumors (WTs), other benign tumors (OBTs), and malignant tumors (MTs). DCE-MRI and DKI quantitative parameters were measured. The Kruskal–Wallis H test and post hoc test with Bonferroni correction and ROC curve were used for statistical analysis. RESULTS: WTs demonstrated the highest K(ep) value (median 1.89, interquartile range [1.46–2.31] min(−1)) but lowest V(e) value (0.20, [0.15–0.25]) compared with PAs (K(ep), 0.34 [0.21–0.55] min(−1); V(e), 0.36 [0.24–0.43]), OBTs (K(ep), 1.22 [0.27–1.67] min(−1); V(e), 0.28 [0.25–0.41]), and MTs (K(ep), 0.71 [0.50–1.23] min(−1); V(e), 0.35 [0.26–0.45]) (all p < .05). MTs had the lower D value (1.10, [0.88–1.29] × 10(−3) mm(2)/s) compared with PAs (1.81, [1.60–2.20] × 10(−3) mm(2)/s) and OBTs (1.57, [1.32–1.89] × 10(−3) mm(2)/s) (both p < .05). PAs had the lower K(trans) value (0.12, [0.07–0.18] min(−1)) compared with OBTs (0.28, [0.11–0.50] min(−1)) (p < .05). The cutoff values of combined K(ep) and V(e), D, and K(trans) to distinguish WTs, MTs, and PAs sequentially were 1.06 min(−1), 0.28, 1.46 × 10(−3) mm(2)/s, and 0.21 min(−1), respectively (accuracy, 89% [71/80], 91% [73/80], 78% [62/80], respectively). CONCLUSION: The combined use of DKI and DCE-MRI may help differentiate parotid gland tumors. KEY POINTS: • The combined use of DKI and DCE-MRI could facilitate the understanding of the pathophysiological characteristics of parotid gland tumors. • A stepwise diagnostic diagram based on the combined use of DCE-MRI parameters and the diffusion coefficient is helpful for accurate preoperative diagnosis in parotid gland tumors and may further facilitate the clinical management of patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00330-021-08312-y.