Parapharyngeal space paraganglioma: distinguishing vagal paragangliomas from carotid body tumours using standard MRI.

<bold>Aim: </bold>To evaluate whether standard magnetic resonance imaging (MRI) could distinguish vagal paragangliomas (VPs) from carotid body tumours (CBTs) in the parapharyngeal space.<bold>Methods and Materials: </bold>Thirteen VPs in 13 patients and 29 CBTs in 26 patients were included in this study. MRI features were evaluated independently by two head and neck radiologists with 10 and 16 years of experience (X.Wang and Y.Chen).<bold>Results: </bold>Significant differences were found in shape, direction of internal carotid artery (ICA) displacement, splaying of the carotid bifurcation, involvement of the jugular foramen, and maximum vertical diameters between VPs and CBTs (p=0.016, <0.001, <0.001, <0.001 and <0.001, respectively). Splaying of the carotid bifurcation was found in all the 29 CBTs for both observers, whereas only four VPs for observer 1 and two for observer 2 showed this feature. The ICA was displaced posteriorly in all the 29 patients with CBTs for both observers, and only three patients with VPs for observer 1 and two for observer 2. Involvement of the jugular foramen was found in seven patients with VPs for both observers, while none of patients with CBT showed this feature. With the combination of splaying of the carotid bifurcation and involvement of the jugular foramen, the multiple logistic regression model revealed the diagnostic accuracy was 95.2% for observer 1 and 97.6% for observer 2. With the combination of ICA displacement direction and involvement of the jugular foramen, the diagnostic accuracy was 97.6% for both observers.<bold>Conclusion: </bold>MRI features can effectively differentiate VPs from CBTs in the parapharyngeal space. [ABSTRACT FROM AUTHOR]