MRI and Orbital Tumours (MEDORT)

Overview

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. The MRI assessment performed routinely in a patient with an orbital mass includes morphological sequences T1, T2 fat suppression, T1 injected fat suppression, diffusion. This exploration requires, regardless of the performed research, a contrast agent injection (0.1 mg / kg weight of Gadobutrol®). In this research protocol, during the injection of the contrast agent performed during the MRI assessment performed routinely, a DCE perfusion sequence, which consists of a repeated acquisition at short intervals of a volume gradient echo T1, will be added. This acquisition will be preceded by two short series for calibration. The post treatment will include parametric permeability cards (Ktrans) and plasmatic volume (Vp), evaluating one or more regions of interest in the tumor, normal lacrimal glands, jaw muscles and nasal mucosa being the reference. It will also be added a magnetic susceptibility EPI sequence type. All the qualitative parameters (T1, T2, T1 injected, distribution, low signal intensity in susceptibility) and quantitative (Ktrans, Vp, relative intensity enhancement, apparent diffusion coefficient) parameters will be collected. The result of the pathological exam of the biopsy or of the surgical specimen, which is the gold-standard, will be collected.

Conditions