Three-dimensional reconstruction and volume calculation of the intraorbital part of the optic nerve with high resolution MRI

Abstract

Optic nerve (ON) always takes attractions of the neuroscientists since the period of ancient scientists like Rufus of the Ephesus and Herophilus of the Chalcedon, accepted as the father of the modern Anatomy.Herophilus wrote his discoveries about the eye from his vivo-sections in the treatise called "On the eye".1 He was first to differentiate between cranial and spinal nerves. AbstractObjectives: Rapid improvements on MRI techniques in recent years brought the investigation of the optic nerve involvement in demyelinating diseases in a detailed manner. This revealed the need to establish standard criteria on defining the pathological conditions related to geriatric population such as optical atrophy, which is more frequently seen in developed countries as well as in our country. This than directed neuroanatomical and neuroradiological studies to the structures like optic nerve that is smaller and hence more difficult to identify with routine MRI sequences. Our aim was to obtain 3D reconstruction and volume calculation of the intraorbital part of the optic nerve from sequential MRI sections. Methods:In this study, 24 female and 24 male volunteers, aged between 20 and 40 have been investigated with T2 weighted MRI sequences with 2mm intervals. The imaging procedures have been performed with Siemens Allegra MRI equipment which has 3 Tesla of magnetic power. Approximately 10 serial sections, from the bulbus oculi to the optic canal, have been used to get the three-dimensional (3D) reconstruction. The 3D reconstruction was produced with the SurfDriver software. The volumes of the intraorbital parts of the optic nerve and their dural sheaths were calculated for either side. Results:The results have been compared with respect to some variables like age, gender, body mass index (BMI) and blood pressure. There was not any statistically significant difference between the volumes with respect to age, gender and BMI. Conclusion:The optic nerve sheath volumes, consequently the subarachnoidal space volumes were significantly increased in either side within the group that had higher values than the normal blood pressure, compared with the normal blood pressure group.