The value of magnetic resonance imaging in the differential diagnosis of parapharyngeal space tumours.

Between 1987 and 1993 14 patients with a parapharyngeal space tumour were imaged by magnetic resonance imaging (MRI). The vagal body tumours, presenting in the poststyloid compartment, all showed flow voids with anterior and medial displacement of the internal carotid artery. None of the salivary gland tumours, all presenting in the prestyloid compartment with posterior displacement of the internal carotid artery, showed flow voids. MRI is superior compared with other modalities in evaluating the differential diagnosis, especially regarding vascular vs non-vascular tumours. It should encompass T1 SE images to assess the presence or absence of flow voids. In vascular tumours angiography must be used to assess feeding vessels, multiplicity, and sides involved. T1 GE images are useful as they allow superior identification of the internal carotid artery and its relation with the tumour accordingly. In addition to T1 SE images, T2 SE images may help in the evaluation of the differential diagnosis. In all non-vascular tumours aspiration cytology is required to differentiate between benign and malignant disease.