Salivary Gland Tumors: Use of Intravoxel Incoherent Motion MR Imaging for Assessment of Diffusion and Perfusion for the Differentiation of Benign from Malignant Tumors

Purpose: To prospectively evaluate the intravoxel incoherent motion (IVIM) parameters (microvascular volume fraction, f; pure diffusion coefficient, D; and perfusion-related incoherent microcirculation, D*) for differentiating between benign and malignant salivary gland tumors. Materials and Methods: All participants in this prospective institutional review board-approved study provided written informed consent. The perfusion and diffusion of 20 (65%) benign (12 pleomorphic adenomas and eight Warthin tumors) and 11 (35%) malignant salivary gland tumors were assessed on the basis of the IVIM theory. Diffusion-weighted magnetic resonance imaging was performed by using 11 b values (0-800 sec/mm(2)). The IVIM parameters of the salivary gland tumors were determined by a radiologist, and significant differences between the tumor types were assessed by using the Steel-Dwass test. Results: The f values of Warthin tumors (0.156 +/- 0.039 [standard deviation]) were significantly larger than those of pleomorphic adenomas (0.066 +/- 0.031) (P = .003). The D values of malignant tumors (0.96 x 10(-3) mm(2)/sec +/- 0.22) were significantly different from those of benign tumors (pleomorphic adenomas, 1.38 x 10(-3) mm(2)/sec +/- 0.30 [P = .002]; Warthin tumors, 0.61 x 10(-3) mm(2)/sec +/- 0.11 [P = .005]). The D* values of malignant tumors (21.99 x 10(-3) mm(2)/sec +/- 19.01) were significantly smaller than those of Warthin tumors (42.64 x 10(-3) mm(2)/sec +/- 20.17) (P = .022). The combination of D and D* criteria provided the best diagnostic accuracy (100%) for differentiation among the three tumor types. Conclusion: IVIM imaging may be helpful for differentiation between benign and malignant salivary gland tumors. (c) RSNA, 2012