Magnetic resonance imaging of the optic nerves and chiasm.

Abstract

Magnetic resonance imaging (MR) of the optic nerves and chiasm was compared with computed tomography (CT) in 4 healthy volunteers, 4 patients without orbital or chiasmal abnormalities, and 4 patients with tumor (anterior clinoid meningioma in 2, optic nerve glioma in 1, and optic nerve sheath meningioma in 1). MR was found to be effective in demonstrating the optic nerves and related structures, particularly the intracanalicular portion of the nerve which is difficult to see with CT. Best results were achieved with partial saturation recovery (SR) images; inversion recovery (IR) and spin echo (SE) techniques were less successful because of decreased spatial resolution (in the case of SE) as well as difficulty in seeing the anterior clinoid processes. As axial views cannot always distinguish the ethmoid sinus tissue from the optic nerve, it may be necessary to employ both axial and coronal images.

Acute postretinal blindness: ophthalmologic, neurologic, and magnetic resonance imaging findings in dogs and cats (seven cases)

“…Several reports describe the findings on standard and advanced MRI images of diseases affecting the globe and visual pathways in humans, such as neoplasms, inflammatory/infectious conditions, vascular, congenital and degenerative disorders. Based upon their location, shape, invasiveness, signal intensity and homogeneity, and enhancement properties, it has often been possible to predict the etiology or malignancy of certain CNS lesions that cause visual deficits or complete blindness as primary clinical sign 3,4,17–24 . In the veterinary literature, little information is available regarding the MRI features of visual pathway lesions 5–11 …”

T1 and T2 measurements of the fine structures of the in vivo and enucleated human eye

“…BECAUSE OF THE very small size of many structures in the human eye, as well as the difficulty with involuntary patient motion of the eye, high resolution and high signal-to-noise ratio (SNR) MRI of the human eye is technically difficult. There are, however, many reports of ocular MRI in the early literature (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). For example, in 1987, Atlas et al (13) retrospectively reviewed their initial experience in 59 patients with MRI of the orbit concluding that there were five specific areas in which MRI ocular imaging provided important information.…”

Primary Diffuse Chiasmatic Germinomas: Differentiation from Optic Chiasm Gliomas

“…Hemorrhage, calcification, and cyst formation are atypical features prior to radiation therapy. With MRI, gliomas of the optic chiasm demon strate a hypointense signal on shortened TR/TE se quences and a hyperintense signal on long TR/TE se quences [14,15]. Large tumors may demonstrate patterns of enhancement that extend posteriorly along the optic pathways to include lateral geniculate bodies and hypo thalamus.…”