Teaching Case

Probable malignant tumour of the left gingiva.

This patient presents with a 3 cm lesion of the left retromolar trigone

After Gd DOTA injection (1c,1d), the natural contrast between the tumour (hyposignal) and the surrounding fat tissues (hypersignal) is partly cancelled owing to tumour enhancement. So the pre-contrast T1 sequence (1a,1b) or an adequately fat-suppressed sequence are necessary. The fat suppression slices (2a,2b) allow to better visualise the tumour lying in a fat area. In addition, abnormalities of the bone marrow are shown. In this case, there is a hypersignal into the ascending branch of the mandible, suspect of tumour invasion. No involvement of the masticator space is seen.