Study On Normal Ophthalmic Tissues Structure Measurement By High-resolution MRI

Part Ⅰ Study on normal ophthalmic tissues among EONs、lacrimal gland and ocular volume structure measurement by High-Resolution MRIObjective The HR-magnetic resonance imaging (MRI) technology was applied to measure the ocular structures of healthy people in order to establish database for ocular structures and provide theoretical support for eye research, teaching and diagnosis.Methods Choose100cases of normal volunteers (200orbits),50cases of male (100orbits),50cases of female orbital (100orbits), all the subjects accepted line HR-orbital MRI, and image processing software was applied to morphology and statistical analysis.1. Measurement of extraocular muscle, muscle belly level horizontal diameter and maximum diameter vertical diameter.2. Eye rectus coordinates, and eye dynamic rectus muscle cross-sectional area.3. The MRI manifestation of lacrimal gland and measurement.4. Eye volume measurementResults l.The EOMs of normal Chinese were symmetrical on the two sides, and following a certain rule. The relationships of the short diameters of EOMs in the Maximum Planes were:IR>MR>SR>LR. That of the long diameters of EOMs were: IR>MR>SR>IR.2.(1) In the primary position, on the plane of eye-optic nerve cross, the coordination of the medial rectus, lateral rectus, superior rectus and inferior rectus muscle relative to the orbital center are (12.53mm,-2.25mm),(-14.35mm,-2.86mm),(1.90mm,12.00mm),(4.80mm,-11.40mm);(2) In the primary position, left, right, up, down gaze, the largest cross-section of the rectus muscles is on the plane of6mm posterior to the plane of eye-optic nerve cross on the images of coronal MRI scan;(3) When the rectus contact and relax, the most obvious change of cross-section is the superior rectus muscle, followed by the inferior rectus, the medial rectus and the lateral rectus muscle, respectively.3.On T2WI the lacrimal gland showed isointensity signal in85and hyperintensity signal in15subjects with respect to the cerebral white matter. On T1WI, the lacrimal gland showed isointensity signal. OnT1WI+FS, the lacrimal gland showed hyperintensity signal. There was no significant difference in the area of the lacrimal gland between sides in men. But in women, the area of the right lacrimal gland was larger than that of left lacrimal. No significant difference was observed in the area of the lacrimal gland between the men and women. There was no significant difference in the Sr of the lacrimal gland between sides in men. But in women, the Sr of the left side lacrimal gland was larger than that of right side. The Sr showed an age-related increase in both men and women.4. The volume of the vitreous cavity4.514±0.323cm3was little different from the anatomic normal value(P=0.148); The volumes of the ocular globe, the anterior chamber, and the lens cavity were5.146±0.352cm3,0.244±0.385cm3,0.223±0.222cm3, with no statistic differences compared with those of the anatomic normal values.Conclusions1.Sizes of EOMs can be assessed by the symmetry on the two sides and by observing the usual rule of EOMs2.We established the rectus muscle coordination of the normal Chinese on the image of coronal orbit MRI and the rate of the cross-section change when the rectus contract and relax in this study, which may help us to diagnose and treat the strabismus.3. Both axial and coronal planes of MR imaging could demonstrate clearly the lacrimal gland. The intensity of the lacrimal gland was similar to the cerebral white matter. Non-enhanced T1WI+FS sequence could show the configuration structure、location and adjacent tissues of the lacrimal gland clearly. Bilateral lacrimal glands were not symmetrical exactly. Lacrimal gland may have anterior、inferior and lateral displacement with age increased.4. MRI could be used for measuring ocular volume. Compared with the anatomic normal value, there was no significant difference in the vitreous cavity volume although the volumes of the lens and the anterior chamber seemed a little bigger.Part Ⅱ Study on the growth of orbital volume in individuals at different ages by MRIObjective To study the growth aspects of orbital volume and to establish the normal value of orbital volume by magnetic resonance imaging (MRI).Method One hundred individuals without eye diseases (50males,50females) were divided into5groups according to the age. Orbital volume and length of horizontal transverse axis and anterior-posterior axis of the eye were measured at different age in MRI. The relationship between orbital volume and age, gender was analyzed. Results There was no difference between the left and right orbital volume in all age groups. Orbital volume grew rapidly before20years of old. Mean orbital volume inmales aged17and females aged13was25.59and23.64ml, respectively, which reached95%of the adult orbital volume. In normal adult, orbital volume in the male was larger than that of the female. The mean orbital volume of adult male and female was27.22±3.37ml and24.88±3.04ml, respectively. A strong linear correlation was presented between the age and orbital volume (P<0.05). If stratified by age, the difference of orbital volume between the male and female was found not to be significant before14(P>0.05).Conclusions There is no remarkable difference between the right and left orbital volume. Orbital volume is associated with age and gender. Orbital volume grows rapidly before20and still grows slowly after40.