[Perfusion analysis in parotid gland tumors using contrast-enhanced ultrasound (CEUS)]

The diagnosis of parotid gland tumors is challenging due to their rarity and heterogenity. Neither conventional ultrasound nor magnetic resonance imaging (MRI) nor computed tomography (CT) allow a reliable pretherapeutic diagnosis. In addition to conventional ultrasound, contrast-enhanced ultrasound (CEUS) enables a more detailed assessment of perfusion in parotid gland tumors, thereby improving evaluation of this tumor entity. Extensive studies with analysis of perfusion characteristics in different regions of interest (ROI) in parotid gland tumors are currently lacking. This study analysed and compared perfusion parameters in different intratumoral areas of malignant and benign parotid gland tumors using CEUS.

A total of 100 patients with tumors in the parotid gland were examined using B‑mode sonography, colour Doppler sonography and CEUS. The parameters magnitude, echogenicity, demarcation, vascularisation and in particular perfusion characteristics were measured and analysed. Analysis of quantitative CEUS parameters was performed using a specific method for perfusion analysis with certain ROI, which were allocated in a standardized manner in the entire parotid gland tumors. The perfusion parameters were compared between intratumoral ROI in the tumors and between particular tumor entities. Qualitative CEUS analysis with an estimation of perfusion patterns was additionally performed.

Histologically benign tumors were found in 92 cases, and malignant tumors in eight cases. CEUS analysis of perfusion patterns revealed a centripetal perfusion pattern in malignant tumors significantly more frequently than in benign tumors. In the perfusion analysis of quantitative CEUS parameters, all tumors showed higher perfusion intensities in the peripheral ROI. In benign tumors, more differences in perfusion intensity between the intratumoral ROIs were detected compared to malignant tumors.

The perfusion parameters (centripetal perfusion pattern; area under the curve) evaluated in this study have the potential to improve pretherapeutic diagnostics of parotid gland tumors in terms of differentiation of tumor entity. Further studies with larger patient cohorts are required for subsequent investigation and validation of the diagnostic accuracy of particular parameters to detect perfusion patterns potentially specific to particular tumor entities.