The Basics of Orbital Imaging

Abstract

In current practice, orbital radiography has been nearly totally abandoned and is now only utilized for the detection of metallic foreign bodies that might preclude MRI, and in rare instances, when CT is unavailable and there is suspicion for gross fracture. Cross-sectional imaging using CT and MRI has now become the primary tool for evaluation of orbital and intracranial pathology. These imaging modalities are also applied to vascular pathology in the form of CTA and MRA, and additional advances have been made in conventional angiography with the advent of digital subtraction angiography (DSA), CT arteriography, and various interventional techniques. These modalities are constantly evolving, and it is important for the ocular oncologist, ophthalmologist, and the oculoplastic surgeon to be aware of all the options in their imaging armamentarium so that they may order the safest, most appropriate study. This chapter primarily covers the basic imaging physics, indications, and contraindications of routine and more advanced CT, MR, and angiographic techniques; it also summarizes some of the image-guided orbital interventions.