Orbital MRI

MRI is a powerful medical imaging technique that provides 3D and sectional images with high anatomical resolution and unrivalled contrast between soft tissues. MRI is noninvasive and does not expose the patient to ionizing radiation. MRI is widely used in orbital imaging for various indications, especially those requiring soft tissue inspection, while CT is preferable for assessment of orbital bony structure, intralesional calcifications, etc. As discussed in a different chapter, CT is faster, and is the imaging modality of choice for orbital trauma and bony tumors; MRI, however, better evaluates most types of orbital tumors and malformations. The versatility of MR sequences enables us to portray anatomical detail to much greater extent, especially when dealing with intraocular or optic nerve/sheath pathologies, inflammatory nerve conditions, perineural spread, as well as bone marrow infiltration, skull base involvement, or cavernous sinus invasion. The current chapter discusses some of the basic principles of MR imaging and its commonly used modalities and sequences.