Orbital masses develop at the expense of the orbital structures lacrimal glands, oculomotor muscles, optic nerve, meningeal spaces, peripheral nerves, bone wall, orbital fat, lymphoid structures or vascular structures. These masses can be tumors, benign or malignant, or pseudotumor, mainly represented by specific or non-specific orbital inflammation.

Pathology is of considerable importance for the diagnosis and the treatment of those masses. However, biopsy or surgical resection of the orbital masses is sometimes difficult and dangerous outside expert centers.

The identification of a non-invasive technique for distinguishing tumors from pseudotumors, thus avoid in some cases a biopsy, would be a major contribution for the patients.

For salivary glands, MRI allows to identify 4 different types of MRI characteristics, one (type C) being related to malignant tumors.

In this study, the investigators will try to see if extrapolation of those data to orbiltal tumors is feasible.

Inclusion Criteria:

• Patient aged 18 years or more
• with orbital mass for which a biopsy and/or a surgical removal is planned
• undergoing an MRI
• before surgery

Exclusion Criteria:

• contra-indication to MRI
• intolerance to constrast agent
• pregnancy
• breast feeding
• patient under a legal protection procedure
• patient denying to participate to the study
• lack of affiliation to a social security system

Patients undergoing a MRI because of an orbital mass