Differences between Proximal versus Distal Intraorbital Optic Nerve Diffusion Tensor Magnetic Resonance Imaging Properties in Glaucoma Patients

Abstract

Purpose. To analyze in vivo the diffusion tensor magnetic resonance imaging (DT-MRI) properties of the intraorbital optic nerve at two different levels: Proximal to the optic nerve head (ONH) and distal to the ONH at the level of the orbital apex in glaucoma patients. Methods. Twenty-four patients with primary open-angle glaucoma were examined. The categorization into early and severe glaucoma was performed by Hodapp's classification. Fifteen healthy individuals served as controls. DT-MRI was performed with a 3T-MR unit. Results. At early stage mean diffusivity (MD) values were higher at the proximal site with respect to the distal site. On the contrary, a decrease in fractional anisotropy (FA) was observed only relative to patient stage, independent of optic nerve site. Moreover, at early disease stage an increase in overall diffusivities, was evident at the proximal site, whereas at the distal site a decrease of the largest diffusivity and an increase in both the intermediate and smallest diffusivities were observed. FA and MD measured at the proximal site, had, respectively, the highest sensitivity and specificity in discriminating between healthy and glaucomatous eyes. Conclusions. Our study represents the first attempt to evaluate in vivo fiber integrity changes along the optic nerve with DT-MRI. Optic nerve degeneration appears to be a process that affects differently the proximal and the distal segments of the optic nerve. The complementary high sensitivity of FA with the high specificity of MD at the proximal site may provide reliable indexes for the identification of glaucomatous patients at early stages

Structural and Functional Evaluation of Glaucomatous Neurodegeneration from Eye to Visual Cortex using 1.5T MR Imaging: A Pilot Study

“…In our study, optic nerve-1 diffusion parameters were found to be more closely correlated with OCT and VF findings. This is also consistent with the recent study of Bolacchi et al in which, proximal optic nerve findings were found to be more closely correlated with OCT data in early stage glaucoma [26].…”

Ophthalmic Magnetic Resonance Imaging at 7 T Using a 6-Channel Transceiver Radiofrequency Coil Array in Healthy Subjects and Patients With Intraocular Masses

“…For this purpose transversal views of the eye were acquired using a spatial resolution of (0.2 x 0.2 x 1.0) mm 3 ( Figure 8a) and of (0.3 x 0.3 x 1.0) mm 3 ( Figure 8b). We could also demonstrate the feasibility of inversion recovery prepared 3D GRE using a spatial resolution of (0.4 x 0.4 x 1.0 mm) 3 ( Figure 8c) and T2-weighted 2D FSE with a spatial resolution of (0.25 x 0.25 x 0.7 mm) 3 ( Figure 8d). For comparison, the T2-weighted 2D FSE protocol was performed using the 1TX24RX, 1TX1RX and 1TX32RX head coil configurations.…”

“…With a spatial resolution of (0.3 x 0.3 x 1.0) mm 3 we could clearly discern anatomical details of the eye including the anterior chamber, posterior chamber, lens nucleus, lens cortex, vitreous humor and orbital muscles (Figure 7a). Rather uniform signal intensity was observed across the eye as underlined by the signal intensity profiles through a sagittal view of the lens nucleus and the vitreous humor (Figure 7b).…”

“…Magnetic resonance imaging (MRI) of the spatial arrangements of the eye segments and their masses is an emerging MRI application [1][2][3][4][5][6][7][8][9]. Ocular MRI holds the potential to provide guidance during diagnostic assessment and treatment of ophthalmological diseases [8,[10][11][12][13].…”

Decision Making for Patients With Concomitant Pituitary Macroadenoma and Ophthalmologic Comorbidity: A Clinical Controversy

“…Glaucomatous optic neuropathy is characterized by a typical appearance of the optic nerve head, including a loss of neuroretinal rim, deepening of the optic cup, disc hemorrhages, parapapillary chorioretinal atrophy, decrease in the diameter of the retinal arterioles, and a diffuse and or local retinal nerve fiber layer loss (4). Formerly the definition of human glaucoma included elevation of IOP over the upper limit of the normal range (most frequently >21 mm Hg) (3).…”