Vascular Pattern Analysis on Microvascular Sonography for Differentiation of Pleomorphic Adenomas and Warthin Tumors of Salivary Glands

Abstract

Objectives-Pleomorphic adenomas and Warthin tumors are the most common salivary gland tumors. It is important to differentiate between them because at least a partial parotidectomy is necessary for pleomorphic adenomas, whereas enucleation is sufficient for Warthin tumors. This study aimed to evaluate the usefulness of vascular pattern analysis using microvascular sonography to differentiate between the tumors. Methods-Sixty-two patients with pathologically proven pleomorphic adenomas (n=38) and Warthin tumors (n=24) were included. For all tumors, grayscale, power Doppler, and microvascular sonographic examinations were performed. Differences in vascular patterns (vascular distribution and internal vascularity) on power Doppler and microvascular sonography as well as grayscale sonographic features (size, shape, border, echogenicity, heterogeneity, and cystic change) between pleomorphic adenomas and Warthin tumors were evaluated. A comparison of diagnostic performances of grayscale sonography with power Doppler sonography and grayscale sonography with microvascular sonography was performed. The level of interobserver agreement between 2 reviewers in diagnosing tumors was evaluated. Results-No grayscale sonographic features showed a significant difference between the tumors. Vascular distributions and internal vascularity on power Doppler sonography (P = .01 and .002) and microvascular sonography (both P < .001) were all significantly different. The diagnostic accuracy of grayscale sonography with microvascular sonography (79.0%) was higher than that of grayscale sonography with power Doppler sonography (72.6%). This difference was significant according to the McNemar test (P = .004). Interobserver agreement was excellent in diagnosing tumors on both grayscale sonography with power Doppler sonography (kappa = 0.83) and grayscale sonography with microvascular sonography (kappa = 0.94). Conclusions-Vascular pattern analysis using microvascular sonography with other sonographic features is helpful for differentiating between pleomorphic adenomas and Warthin tumors.