title: Orbital tumours and tumour-like lesions: exploring the armamentarium of multiparametric imaging.
abstract: Although the orbit is a small anatomical space, the wide range of structures present within it are often the site of origin of various tumours and tumour-like conditions, both in adults and children. Cross-sectional imaging is mandatory for the detection, characterization, and mapping of these lesions. This review focuses on multiparametric imaging of orbital tumours. Each tumour is reviewed in relation to its clinical presentation, compartmental location, imaging characteristics, and its histological features. We herein describe orbital tumours as lesions of the globe (retinoblastoma, uveal melanoma), optic nerve sheath complex (meningioma, optic nerve glioma), conal-intraconal compartment (hemangioma), extraconal compartment (dermoid/epidermoid, lacrimal gland tumours, lymphoma, rhabdomysarcoma), and bone and sinus compartment (fibrous dysplasia). Lesions without any typical compartmental localization and those with multi-compartment involvement (veno-lymphatic malformation, plexiform neurofibroma, idiopathic orbital pseudotumour, IgG4 related disease, metastases) are also reviewed. We discuss the role of advanced imaging techniques, such as MR diffusion-weighted imaging (DWI), diffusion tensor imaging, fluoro-2-deoxy-D-glucose positron emission tomography CT (FDG-PET CT), and positron emission tomography MRI (MRI PET) as problem-solving tools in the evaluation of those orbital masses that present with non-specific morphologic imaging findings. Main messages/Teaching points • A compartment-based approach is essential for the diagnosis of orbital tumours. • CT and MRI play a key role in the work-up of orbital tumours. • DWI, PET CT, and MRI PET are complementary tools to solve diagnostic dilemmas. • Awareness of salient imaging pearls and diagnostic pitfalls avoids interpretation errors.
authors.affiliation: Department of Radiology, Geneva University Hospital and University of Geneva, Rue, Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland.
authors.forename: Bela S
authors.initials: BS
authors.lastname: Purohit
authors.affiliation: Department of Neuroradiology, Geneva University Hospital and University of Geneva, Rue, Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland.
authors.forename: Maria Isabel
authors.initials: MI
authors.lastname: Vargas
authors.affiliation: Department of Radiology, Geneva University Hospital and University of Geneva, Rue, Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland.
authors.forename: Angeliki
authors.initials: A
authors.lastname: Ailianou
authors.affiliation: Department of Radiology, Geneva University Hospital and University of Geneva, Rue, Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland.
authors.forename: Laura
authors.initials: L
authors.lastname: Merlini
authors.affiliation: Department of Radiology, Geneva University Hospital and University of Geneva, Rue, Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland.
authors.forename: Pierre-Alexandre
authors.initials: PA
authors.lastname: Poletti
authors.affiliation: Department of Radiology, Geneva University Hospital and University of Geneva, Rue, Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Platon
authors.affiliation: Department of Radiology, Geneva University Hospital and University of Geneva, Rue, Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland.
authors.forename: Bénédicte M
authors.initials: BM
authors.lastname: Delattre
authors.affiliation: Department of Nuclear Medicine, Geneva University Hospital and University of Geneva, Rue, Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland.
authors.forename: Olivier
authors.initials: O
authors.lastname: Rager
authors.affiliation: Department of Clinical Pathology, Geneva University Hospital and University of Geneva, Rue, Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland.
authors.forename: Karim
authors.initials: K
authors.lastname: Burkhardt
authors.affiliation: Department of Radiology, Geneva University Hospital and University of Geneva, Rue, Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland. Minerva.Becker@hcuge.ch.
authors.forename: Minerva
authors.initials: M
authors.lastname: Becker
keywords: Diffusion weighted imaging (DWI); Magnetic resonance imaging (MRI); Orbit tumours; Positron emission tomography CT (PET CT); Positron emission tomography MRI (MRI PET)