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Evaluation of parotid gland lesions with standard ultrasound, color duplex sonography, sonoelastography, and acoustic radiation force impulse imaging - a pilot study.

PURPOSE
To evaluate the impact of standard ultrasound (US), color duplex sonography (CDS), sonoelastography (SE), and acoustic radiation force impulse (ARFI) imaging in the differentiation of parotid gland lesions.


MATERIALS AND METHODS
From September 2010 to February 2011, 33 parotid gland lesions of 32 patients were included in this study. Patients underwent high-resolution B-mode US (THI, 9 - 14 MHz), CDS, SE, and ARFI quantification. Then parotidectomy was performed and samples were analyzed by (immuno-) histology. Data was extracted via unpaired t-test and expressed in p-values.


RESULTS
There were 12 Wathin's tumors (WT), 11 pleomorphic adenomas (PA), 3 other benign tumors, 3 ductal dilatations, 2 neuroendocrine carcinomas, 1 non-Hodgkin lymphoma, and 1 malignant melanoma metastasis. In B-mode US, acoustic enhancement showed statistical significance between PA and WT (p < 0.005), and CDS determined different vascularization patterns (p < 0.0005). While SE did not visualize any significant difference between PA and WT, ARFI quantification determined different mean values for both entities (p < 0.003).


CONCLUSION
B-mode US, CDS, and ARFI quantification distinguish PA from WT. The predictive value of the modern techniques for the differentiation of benign and malignant parotid lesions has to be assessed in a larger series.