When is magnetic resonance imaging (MRI) better than CT?
advantages of MRI MRI crucial in adult with vision loss; compressive optic neuropathy, optic nerve sheath meningioma, or sphenoid wing meningioma causing vision loss can be missed on CT and seen on MRI; in children with orbital tumors, MRI pattern pathognomonic in differentiating hemangioma from rhabdomyosarcoma; apart from those exceptions, CT cost-effective and reasonable; advantages of CT new helical or spiral CTs can image whole orbit in <1 min; in very young children, anesthesia unnecessary; CT probably best choice if patient has trauma; patients with pacemaker, who are claustrophobic, or who have magnetic material implanted cannot use MRI; bone invasion better delineated on CT
